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Term: Absorption

Definition: The process of taking in. For a person or an animal, absorption is the process of a substance getting into the body through the eyes, skin, stomach, intestines, or lungs.

Source: ATSDR Glossary of Terms

Term: Acceptable Daily Intake (ADI)

Definition: Estimate of the amount of a substance in food and/or drinking water, expressed on a body weight basis that can be ingested daily over a lifetime without appreciable health risk to the consumer on the basis of all the known facts at the time of the evaluation.
The ADI is usually expressed in milligrams of the chemical per kilogram of body weight. ADIs are used for substances that have a reason to be found in food (as opposed to a contaminant - see TDI) and as such, include additives, pesticide residues and veterinary drugs in foods.

Source: GreenFacts Glossary


Definition: The American Conference of Governmental Industrial Hygienists

Term: Acute exposure

Definition: Contact with a substance that occurs once or for only a short time (up to 14 days [for humans])

Source: ATSDR Glossary of Terms

Term: Additive processing

Definition: Adding a layer of new material, in order to leave a pattern of deposited material on the substrate.

Source: ISO/TS 80004-8:2013

Term: Adduct

Definition: In biology, an adduct is a complex that forms when a chemical binds to a biological molecule, such as DNA or protein.

Source: GreenFacts Glossary

Term: Adenocarcinoma

Definition: Adeno- is a prefix which means "gland". Adenocarcinoma is a cancerous tumour that starts in cells with gland-like properties (i.e. they have a secretory function) that line some internal organs. The majority of all breast, colon, and prostrate cancers are adenocarcinomas.

Source: GreenFacts Glossary

Term: Adverse Effects

Definition: An abnormal, undesirable, or harmful effect to an organism, indicated by an end result such as mortality, altered food consumption, altered body and organ weights.

Term: Adsorption

Definition: EIncrease in the concentration of a substance at the interface of a condensed and a liquid or a gaseous layer owing to the operation of surface forces.

Source: NLM Toxicology Glossary

Term: Aerodynamic particle sizer (APS)

Instrument which uses time-of-flight light-scattering technique to measure aerodynamic diameter in real time.

Term: Aerosol

Definition: System of solid or liquid particles suspended in gas.

Source: ISO 15900:2009

Term: Aetiology

Definition: The investigation of the cause or origin of disease.

Term: Agglomerate

Definition: Collection of weakly bound particles or aggregates or mixtures of the two where the resulting external surface area is similar to the sum of the surface areas of the individual components.

Source: ISO/TS 80004-2:2015

Term: Aggregate

Definition: Particle comprising strongly bonded or fused particles where the resulting external surface area may be significantly smaller than the sum of calculated surface areas of the individual components.

Source: ISO/TS 80004-2:2015

Term: AHIA

Definition: The American Industrial Hygiene Association.

Term: Allergen

Definition: Any substance which produces an allergy.

Term: Allergy (hypersensitivity)

Definition: Disease symptoms following exposure to a previously encountered substance (allergen), often one which would otherwise be classified as harmless; essentially a malfunction of the immune system.

Term: Alveoli

Definition: Thin-walled, tiny air sacs located at the ends of the smallest airways in the lungs (the bronchioles) where the exchange of oxygen and carbon dioxide takes place.

Source: GreenFacts Glossary

Term: Anemia

Definition: A deficiency of red blood cells in the bloodstream, resulting in insufficient oxygen being carried to tissues and organs. Symptoms of anemia include feeling tired, weak, and short of breath.

Source: GreenFacts Glossary

Term: Antagonistic effect

Definition: A biologic response to exposure to multiple substances that is less than would be expected if the known effects of the individual substances were added together.

Source: ATSDR Glossary of Terms

Term: Anthropogenic

Definition: Originating from the activity of humans.

Source: GreenFacts Glossary

Term: Antibody

Definition: A protein produced by the body's immune system that recognises and helps fight infections and other foreign substances in the body.

Source: GreenFacts Glossary

Term: Antioxidant

Definition: Any substance that prevents or reduces damage caused by free-radicals (highly reactive chemicals containing oxygen) which attack other molecules and modify their chemical structure. Antioxidants are commonly used as preservatives in food or cosmetics. Well-known antioxidants include vitamins A, C, and E.

Term: Apoptosis

Definition: Active process of programmed cell death, requiring metabolic energy, often characterized by fragmentation of DNA, and cell deletion without associated inflammation.

Source: NLM Toxicology Glossary

Term: Arrhythmia

Definition: Any variation from the normal rhythm of the heartbeat.

Source: NLM Toxicology Glossary

Term: Aryl hydrocarbon receptor (Ah-receptor)

Definition: A protein within the cell that binds to aryl hydrocarbons forming a complex that moves into the nucleus of the cell. In the nucleus, this complex controls the onset of a series of biotransformation processes for the excretion of hydrocarbon compounds. Ah-receptor binding, may, however also result in the synthesis of other proteins, some of which may interfere adversely with cellular growth and differentiation (specialisation).

Source: GreenFacts Glossary

Term: Aspect ratio

Definition: Ratio of length of a particle to its width.

Source: ISO 14966:2002

Term: Assay

Definition: Process and results of quantitative or qualitative analysis of a component of a sample.

Source: NLM Toxicology Glossary

Term: Asthma

Definition: Chronic respiratory disease characterised by bronchoconstriction, excessive mucus secretion and oedema of the pulmonary alveoli, resulting in difficulty in breathing out, wheezing, and cough.

Source: NLM Toxicology Glossary

Term: Atomic Force Microscopy / Microscope (AFM)

Definition: Method for imaging surfaces by mechanically scanning their surface contours, in which the deflection of a sharp tip sensing the surface forces, mounted on a compliant cantilever, is monitored.

Source: ISO 18115‑2:2010

Term: Auger electron spectroscopy (AES)

Definition: Method in which an electron spectrometer is used to measure the energy distribution of Auger electrons emitted from a surface.

Source: ISO 18115-1:2010

Term: Autoimmunity

Definition: Autoimmunity happens when the body fails to recognise some of its own tissues or cells and attacks them as if they were foreign. Diseases arising from this abnormal immune response are called autoimmune diseases. Examples of autoimmune diseases include type 1 diabetes and lupus.

Source: GreenFacts Glossary

Term: Bioaccumulation

Definition: Progressive increase in the amount of a substance in an organism or part of an organism which occurs because the rate of intake exceeds the organism’s ability to remove the substance from the body.

Source: NLM Toxicology Glossary

Term: Bioassay

Definition: Procedure for estimating the concentration or biological activity of a substance (e.g. hormone, plant growth factor, antibiotic etc.) by measuring its effect on an organism compared to an appropriate standard preparation.

Source: NLM Toxicology Glossary

Term: Biocide

Definition: A chemical with the capacity to kill organisms. Examples include pesticide, antimicrobial pesticides, herbicides, fungicides and insecticides.

Source: GreenFacts Glossary 

Term: Bioconcentration

Definition: The accumulation of a chemical in tissues of a fish or other organism to levels greater than that in the surrounding medium (environment).

Source: US EPA Terms of Environment Glossary

Term: Biodiversity

Definition: Biodiversity is a contraction of biological diversity. Biodiversity reflects the number, variety and variability of living organisms. It includes diversity within species (genetic diversity), between species (species diversity), and between ecosystems (ecosystem diversity).

Source: GreenFacts Glossary

Term: Bioinformatics

Definition: The science of informatics as applied to biological research. Informatics is the management and analysis of data using advanced computing techniques. Bioinformatics is particularly important as an adjunct to genomics research, because of the large amount of complex data this research generates.

Source: FSA Genomics: Glossary of Terms

Term: Biological intake

Definition: The process by which a substance crosses the outer boundary of an organism without passing an absorption barrier, e.g. through ingestion or inhalation.

Source: US EPA Health Effects Glossary

Term: Biological monitoring

Definition: Periodic examination of biological specimens for the purposes of monitoring. It is usually applied to exposure monitoring but can also apply to effect monitoring. Analysis of the amounts of potentially toxic substances or their metabolites present in body tissues and fluids, as a means of assessing exposure to these substances and aiding timely action to prevent adverse effects.

Term: Biological uptake

Definition: The transfer of substances from the environment to plants, animals, and humans.

Source: ATSDR Glossary of Terms

Term: Biological half-life

Definition: The time required for the amount of a particular substance in a biological system to be reduced to one half of its value by biological processes.

Term: Biomagnification

Definition: The term biomagnification refers to the progressive build up of persistent substances by successive trophic levels - meaning that it relates to the concentration ratio in a tissue of a predator organism as compared to that in its prey.

Source: GreenFacts Glossary

Term: Biomarker

Definition: 1. Parameter that can be used to identify a toxic effect in an individual organism and can be used in extrapolation between species.

Term: Bionanotechnology

Definition: Application of biology to nanotechnology, i.e. the use of biological molecules in nanomaterials, nanoscale devices or nanoscale systems.

Source: ISO/TS 80004-5:2011

Term: Blood serum

Definition: Clear, watery fluid of the blood that separates when blood clots.

Term: Blood-brain barrier (BBB)

Definition: A protective barrier between brain blood vessels and brain tissues that allows blood to flow freely to the brain but prevents most substances in the bloodstream from reaching the brain cells. The BBB protects the brain from the effect of many harmful substances but makes it difficult to deliver drugs to the brain.

Term: Body burden

Definition: The total amount of a substance in the body. Some substances build up in the body because they are stored in fat or bone or because they leave the body very slowly.

Term: Bottom-up vs Top-down

Definition: There are two approaches for the manufacturing of nanomaterials:

Term: Bottom-up nanomanufacturing

Definition: Processes that use small fundamental units in the nanoscale to create larger functionally rich structures or assemblies.

Source: ISO/TS 80004-8:2013

Term: Brunauer–Emmett–Teller (BET) method

Method for the determination of the total specific external and internal surface area of disperse powders and/or porous solids by measuring the amount of physically adsorbed gas utilising the model developed.

Source: ISO/TS 80004-6:2013

Term: Cancer

Definition: A disease which results from the development of a malignant tumour and its spread into surrounding tissues.

Term: Cancer risk

Definition: A theoretical risk for getting cancer if exposed to a substance every day for 70 years (a lifetime exposure). The true risk might be lower.

Term: Carbon black

An industrially manufactured colloidal carbon material in the form of spheres and of their aggregates with sizes below 1 000 nm.

Source: IUPAC Compendium of Chemical Terminology

Term: Carbon nanofibre (CNF)

Definition: Nanofibre composed of carbon.

Source: ISO/TS 80004-3:2010

Term: Carbon nanohorn

Definition: Short and irregular shaped carbon nanotube with a nanocone apex.

Source: ISO/TS 80004-3:2010

Term: Carbon nanopeapod

Definition: Linear array of fullerenes enclosed in a carbon nanotube.

Source: ISO/TS 80004-3:2010

Term: Carbon nanoribbon

Definition: Nanoribbon composed of carbon.

Source: ISO/TS 80004-3:2010

Term: Carbon nanotube (CNT)

Definition: Nanotube composed of carbon.

Source: ISO/TS 80004-3:2010

Term: Carcinogen

Definition: A substance which causes cancer.

Term: Carcinoma

Definition: A carcinoma is a cancerous tumour that starts in tissues covering or lining various organs of the body or in glands, such as skin, uterus, prostate, breast, or stomach. Carcinomas tend to infiltrate into nearby tissues. They may also spread to distant organs such as lung, bone, liver, or the brain. Carcinomas are the most common type of cancer.

Term: Cardiopulmonary

Definition: Having to do with the heart and lungs.

Term: Ceiling value

Definition: U.S. term in occupational exposure indicating the airborne concentration of a potentially toxic substance which should never be exceeded in a worker’s breathing zone.

Term: Cell culture

Definition: The process of growing and maintaining cells under laboratory conditions, commonly on a glass surface immersed in nutrient fluid.

Term: Cell line

Definition: A defined population of cells which has been maintained in a culture for an extended period, as used in in vitro experiments.

Term: Cell membrane

Definition: The cell membrane is a fine structure that envelops a cell, separating the content of the cell from its surroundings. It regulates the substances that can enter and leave the cell. The membrane consists of a double layer of lipids in which proteins are embedded.

Term: Cell nucleus

Definition: The centre of a cell, where [most] of the DNA, packaged in chromosomes, is contained.

Term: Cellulose

Definition: The principal component of cell walls of plants, composed of a complex polyose.

Term: Chemical Vapour Deposition (CVD)

Definition: Deposition of a solid material by chemical reaction of a gaseous precursor or mixture of precursors, commonly initiated by heat on a substrate.

Source: ISO/TS 80004-8:2013

Term: CHIP

Definition: Chemicals (Hazard Information and Packaging for Supply) Regulations. These relate to the implementation of a variety of EC (European Community) regulations, and were first introduced in 1993. The CHIP regulations are of concern primarily to suppliers, and require that they i) Identify the hazards associated with the chemicals they supply; ii) Give that information to those receiving or transporting the chemicals; and iii) Package the chemicals safely.

Term: Chromatography

Definition: The physical method of separation in which the components to be separated are distributed between two phases, one of which is stationary while the other moves in a definite direction. Chromatography is a widely used for the separation, identification, and determination of the chemical components in complex mixtures.

Source: Institute of Nanotechnology Glossary

Term: Chronic

Definition: Occurring over a long period of time, either continuously or intermittently; used to describe ongoing exposures and effects that develop only after a long exposure.

Term: Chronic exposure

Definition: Contact with a substance that occurs over a long time (more than 1 year [for humans]).

Term: Chronic toxicity

Definition: 1. Adverse effects following chronic exposure;
2. Effects which persist over a long period of time whether or not they occur immediately upon exposure or are delayed.

Source: NLM Toxicology Glossary

Term: Circulatory system

Definition: The system that contains the heart and the blood vessels and moves blood throughout the body. This system helps tissues get enough oxygen and nutrients, and it helps them get rid of waste products. The lymph system, which connects with the blood system, is often considered part of the circulatory system.

Source: NCI Dictionary of Cancer Terms

Term: Coagulation

Definition: The clumping together of very fine particles to form larger particles; caused by the use of chemicals (coagulants). The chemicals neutralise the electrical charges of the fine particles and cause destabilisation of the particles. The clumping together makes it easier to separate the solids from the water by settling, skimming, draining or filtering.

Source: US EPA Drinking Water Glossary

Term: Co-deposition

Definition: Simultaneous deposition of two or more source materials.

Source: ISO/TS 80004-8:2013

Term: Cognitive

Definition: Having to do with the ability to think and reason. This includes the ability to concentrate, remember things, process information, learn, speak, and understand.

Term: Cohort

Definition: A group of individuals, identified by a common characteristic, who are studied over a period of time as part of an epidemiological investigation.

Term: Colloid

Definition: A mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also called a colloidal system, colloidal solution, or colloidal dispersion. Colloid science is the study of systems involving small particles of one substance suspended in another. Suspensions in liquids form the basis of a wide variety of systems of scientific and technological importance, including paints, ceramics, cosmetics, agricultural sprays, detergents, soils, biological cells, and many food preparations.

Source: NLM Toxicology Glossary

Term: Comet assay

Definition: The comet assay, also known as the single-cell gel electrophoresis (SCGE) assay is a versatile, sensitive and rapid method for measuring DNA single- and double-strand breaks at the level of individual cells. The technique can also be adapted for the quantification of alkali-labile sites, oxidative base damage, DNA–DNA or DNA–protein cross-linking and abasic sites.

Term: Composites

Definition: Combinations of metals, ceramics, polymers, and biological materials that allow multi-functional behaviour. One common practice is reinforcing polymers or ceramics with ceramic fibres to increase strength while retaining light weight and avoiding the brittleness of the monolithic ceramic. Materials used in the body often combine biological and structural functions (e.g. the encapsulation of drugs).

Source: NLM Toxicology Glossary

Term: Condensation Particle Counter (CPC)

Instrument that measures the particle number concentration of an aerosol.

Source: ISO 15900:2009

Term: Confocal microscopy

Definition: Technique used to increase image contrast and/or to reconstruct 3- dimensional images by using a spatial pinhole to eliminate out-of-focus light or flare in specimens that are thicker than the focal plane.

Source: Nanocharm Glossary of Terms

Term: Confocal optical microscopy

Definition:Method for microscopy in which, ideally, a point in the object plane is illuminated by a diffraction-limited spot of light, and light emanating from this point is focused upon and detected from an area smaller than the central area of the diffraction disc situated in the corresponding position in a subsequent field plane.

Source: ISO 10934‑2:2007

Term: Confounding factor

Definition: A confounding factor in a study is a variable which is related to one or more of the variables defined in a study. A confounding factor may mask an actual association or falsely demonstrate an apparent association between the study variables where no real association between them exists. If confounding factors are not measured and considered, bias may result in the conclusion of the study.

Source: GreenFacts Glossary

Term: Control group

Definition: Selected group, identified as a rule before a study is done, which comprises humans, animals, or other species who do not have the disease, intervention, procedure or whatever is being studied, but in all other respects is as nearly identical to the test group as possible.

Source: NLM Toxicology Glossary

Term: Control limit

Definition: A regulatory value applied to the airborne concentration in the workplace of a potentially toxic substance which is judged to be "reasonably practicable" for the whole spectrum of work activities and which must not normally be exceeded.

Term: Controlled study

Definition: An experiment or clinical trial in which two groups are used for comparison purpose.

Source: GreenFacts Glossary

Term: Cup-stack carbon nanotube

Carbon nanotube composed of stacked truncated graphene nanocones.

Source: ISO/TS 80004-3:2010

Term: Cytotoxic

Definition: A substance which is harmful to cell structure and function and ultimately causing cell death.

Term: Daphnia

Definition: Very small freshwater crustacean, which moves by means of its larges antennae's. Also known as "water flea", due to its specific motion.

Source: GreenFacts Glossary

Term: Deposition

Definition: 1. Process by which a substance arrives at a particular organ or tissue site, for example the deposition of particles on the ciliated epithelium of the bronchial airways;

Term: Dermal

Definition: Pertaining to the skin.

Source: NLM Toxicology Glossary

Term: Dermal irritation

Definition: A localised skin reaction resulting from either single or multiple exposure to a physical or chemical agent at the same site.

Term: Desorption

Definition: Opposite of adsorption; a decrease in the amount of adsorbed substance.

Source: NLM Toxicology Glossary

Term: Developmental toxicity

Definition: Adverse effects on the developing organism (including structural abnormality, altered growth, or functional deficiency or death) resulting from exposure prior to conception (in either parent), during prenatal development, or postnatally up to the time of sexual maturation.

Source: NLM Toxicology Glossary

Term: Differential mobility analysing system (DMAS)

Definition: System to measure the size distribution of submicrometre aerosol particles consisting of a differential electrical mobility classifier, flow meters, a particle detector, interconnecting plumbing, a computer and suitable software.

Source: ISO 15900:2009

Term: Differential electrical mobility classifier (DEMC)

Definition: Classifier that is able to select aerosol particles according to their electrical mobility and pass them to its exit.

Source: ISO 15900:2009

Term: Differential scanning calorimetry (DSC)

Definition: Method in which the difference in energy inputs into a substance and a reference material is measured as a function of temperature while the substance and reference material are subjected to a controlled temperature programme.

Source: ISO 472:2013

Term: Diffusion charger

Definition: Real-time measurement of aerosol active surface area. Active surface area does not scale directly with geometric surface area above 100 nm. Note that not all commercially available diffusion chargers have a response that scales with the particle active surface area below 100 nm. Diffusion chargers are only specific to nanoparticles if used with an appropriate inlet preseparator.

Source: BSI PD6699-3:2010

Term: Directed assembly

Definition: Formation of a structure guided by external intervention using components at the nanoscale that can, in principle, have any defined pattern.

Source: ISO/TS 80004-8:2013

Term: Distribution

Definition: 1. Dispersal of a substance and its derivatives throughout the natural environment;

Term: Dose

Definition: The amount of a substance to which a person is exposed over some time period. Dose is a measurement of exposure. Dose is often expressed as milligram (amount) per kilogram (a measure of body weight) per day (a measure of time) when people eat or drink contaminated water, food, or soil. In general, the greater the dose, the greater the likelihood of an effect. An "exposure dose" is how much of a substance is encountered in the environment. An "absorbed dose" is the amount of a substance that actually got into the body through the eyes, skin, stomach, intestines, or lungs.

Source: ATSDR Glossary of Terms

Term: Dose-response curve

Definition: This is a graph to show the relation between the dose of a drug or xenobiotic and the degree of response it produces, as measured by the percentage of the exposed population showing a defined, effect. If the effect determined is death, such a curve may be used to estimate an LD50 value.

Term: Dose-response relationship

Definition: The relationship between the amount of exposure [dose] to a substance and the resulting changes in body function or health (response).

Source: ATSDR Glossary of Terms

Term: Double-wall carbon nanotube (DWCNT)

Definition: Multiwall carbon nanotube composed of only two nested, concentric single-wall carbon nanotubes.

Source: ISO/TS 80004-3:2010

Term: Dry ball milling

Definition: Creation of nanoparticles via rolling feedstock material with crushing balls of greater hardness to mix two or more immiscible nanoparticles which are then heated to sinter them.

Source: ISO/TS 80004-8:2013

Term: DustTrak

Definition: Air sampling instrument which uses a laser photometer that simultaneously measures both mass and size fraction of airborne particulates.

Term: Dynamic Light Scattering (DLS)

Definition: Method in which particles undergoing Brownian motion in a liquid suspension are illuminated by a laser and the change in intensity of the scattered light is used to determine particle size.

Source: ISO/TS 80004-6:2013

Term: Ecotoxicology

Definition: Ecotoxicology is the science devoted to the study of the production of harmful effects by substances entering the natural environment, especially effects on populations, communities, and ecosystems; an essential part of ecotoxicology is the assessment of movement of potentially toxic substances through environmental compartments and through food webs.

Term: Effective concentration (EC)

Definition: Concentration of a substance that causes a defined magnitude of response in a given system: EC50 is the median concentration that causes 50% of maximal response.

Term: Effective dose (ED)

Definition: Dose of a substance that causes a defined magnitude of response in a given system: ED50 is the median dose that causes 50 % of maximal response.

Term: Electric surface charge density

Definition: Charges on an interface per area due to specific adsorption of ions from the liquid bulk, or due to dissociation of the surface groups.

Source: ISO 13099‑1:2012

Term: Electrical low pressure impactor (ELPI)

Definition: Real-time size-selective (aerodynamic diameter) detection of active surface-area concentration. Data may be interpreted in terms of mass concentration if particle charge and density are assumed or known. Size-selected samples may be further analysed off-line.

Source: BSI PD6699-3:2010

Term: Electro Scanning Microscope

Definition: Used for the study of surface morphology and the determination of the thickness of MBE grown films.

Source: Institute of Nanotechnology Glossary

Term: Electron energy loss spectroscopy (EELS)

Definition: Method in which an electron spectrometer measures the energy spectrum of electrons from a nominally monoenergetic source emitted after inelastic interactions with the sample, often exhibiting peaks due to specific inelastic loss processes.

Source: ISO 18115‑1:2010

Term: Electron paramagnetic resonance (EPR)

Definition: Method for studying chemical species that have one or more unpaired electrons through resonant excitation of electron spin.

Source: ISO/TS 80004-6:2013

Term: Electron spectrometer

Definition: Device, the essential part of which is used for measuring the number of electrons, or an intensity proportional to that number, as a function of the electron kinetic energy.

Source: ISO 18115‑1

Term: Electron spin resonance (ESR)

Definition: Method for studying chemical species that have one or more unpaired electrons through resonant excitation of electron spin.

Source: ISO/TS 80004-6:2013

Term: Electroplating

Definition: Deposition of material onto an electrode surface from ions in solution due to electrochemical reduction.

Source: ISO/TS 80004-8:2013

Term: Electrostatic force microscopy (EFM)

Definition: AFM mode in which a conductive probe is used to map both topography and electrostatic force between the tip and the sample surface.

Source: Nanocharm Glossary of Terms

Term: Elimination

Definition: Expulsion of a substance or other material from an organism (or a defined part thereof), usually by a process of extrusion or exclusion, sometimes after metabolic transformation.

Term: Endocrine

Definition: Pertaining to hormones or to the glands that secrete hormones directly into the bloodstream.

Source: NLM Toxicology Glossary

Term: Endocrine disruptor

Definition: A natural or man-made chemical that can interfere with endocrine glands and their hormones or where the hormones act - the target tissues.

Source: GreenFacts Glossary

Term: Endpoint

Definition: A biological endpoint is a direct marker of disease progression - e.g. disease symptoms or death - used to describe a health effect (or a probability of that health effect) resulting from exposure to a chemical.

Source: GreenFacts Glossary

Term: Energy-dispersive x-ray spectroscopy (EDX or EDS)

Definition: X-ray spectrometry in which the energy of individual photons are measured by a parallel detector and used to build up a histogram representing the distribution of X-rays with energy.

Source: ISO 22309:2011

Term: Engineered nanomaterial

Definition: Nanomaterial designed for a specific purpose or function.

Source: ISO/TS 80004-1:2010

Term: Environmental exposure level (EEL)

Definition: Level (concentration or amount or a time integral of either) of a substance to which an organism or other component of the environment is exposed in its natural surroundings.

Term: Environmental fate

Definition: Destiny of a chemical or biological pollutant after release into the natural environment.

Source: NLM Toxicology Glossary

Term: Environmental health impact assessment

Definition: Estimate of the adverse health effects or risks likely to follow from a proposed or expected environmental change or development.

Source: NLM Toxicology Glossary

Term: Epidemiology

Definition: Epidemiology is the science devoted to the statistical study of categories of persons and the patterns of diseases from which they suffer, with the aim of determining the events or circumstances causing these diseases. Epidemiology studies on human populations attempt to link human health effects (e.g. cancer) to a cause (e.g. exposure to a specific chemical).

Term: Epidermis

Definition: In humans and animals, epidermis refers to the thin outermost layer of the skin. This tissue constantly renews itself.

Term: Equivalent diameter

Diameter of a sphere that produces a response by a given particle-sizing instrument, that is equivalent to the response produced by the particle being measured.

Source: ISO/TS 27687:2008

Term: Eukaryote

Definition: Cell or organism with the genetic material packed in a membrane-surrounded structurally discrete nucleus and with well-developed cell organelles. The term includes all organisms except archaebacteria, eubacteria and cyanobacteria (until recently classified as cyanophyta or blue-green algae).

Source: NLM Toxicology Glossary

Term: Excretion

Definition: Discharge or elimination of an absorbed or endogenous substance, or of a waste product, and/or their metabolites, through some tissue of the body and its appearance in urine, faeces, or other products normally leaving the body. Excretion of chemical compounds from the body occurs mainly through the kidney and the gut. Volatile compounds may be largely eliminated by exhalation. Excretion by perspiration and through hair and nails may also occur. Excretion by the gastrointestinal tract may take place by various routes such as the bile, the shedding of intestinal cells and transport through the intestinal mucosa.

Source: NLM Toxicology Glossary

Term: Exfoliated graphite

Definition: A multilayer made by partial exfoliation (thermal, chemical, or mechanical) of graphite into thin multilayer packets that retain the 3D crystal stacking of graphite. This is an operational definition – one based on the fabrication process rather than the resulting material – and as such can overlap with other definitions such as graphite nanoplates.

Source: Bianco et al. (2013)

Term: Exposure

Definition: Concentration or amount of a NP or other chemical agent that reaches a target organ or system, an organism or a population.

Term: Exposure Assessment

Definition: Process of measuring or estimating concentration (or intensity), duration and frequency of exposures to an agent present in the environment or, if estimating hypothetical exposures, that might arise from the release of a substance, or radionuclide, into the environment.

Source: NLM Toxicology Glossary

Term: Exposure Limit

Definition: General term defining an administrative substance concentration or intensity of exposure that should not be exceeded.

Source: NLM Toxicology Glossary

Term: Exposure pathway

Definition: The physical route by which a chemical substance transfers from a source to exposed organisms.

Potential pathways include air, surface water, groundwater, soil, plants, animals and humans. May not necessarily always refer to contaminants.

Source: GreenFacts Glossary

Term: Exposure Scenario

Definition: A set of conditions or assumptions about sources, exposure pathways, amount or concentrations of NPs involved, and exposed organism, system or (sub) population (i.e. numbers, characteristics, habits) used to aid in the evaluation and quantification of exposure(s) in a given situation.

Term: Extracellular matrix (ECM)

Definition: A complex structural entity surrounding and supporting cells that are found within mammalian tissues. The ECM is often referred to as the connective tissue. The ECM is composed of three major classes of biomolecules: structural proteins (collagen and elastin) specialized proteins (e.g. fibrillin, fibronectin, and laminin); and proteoglycans: (composed of a protein core to which is attached long chains of repeating disaccharide units termed of glycosaminoglycans (GAGs) forming extremely complex high molecular weight components of the ECM).

Term: Extrapolation

Definition: Calculation, based on quantitative observations in exposed test species or in vitro test systems, of predicted dose-effect and dose-response relationships for a substance in humans and other biota including interspecies extrapolations and extrapolation to susceptible groups of individuals: the term may also be used for qualitative information applied to species or conditions that are different from the ones in which the original investigations were carried out.

Source: NLM Toxicology Glossary

: Fast mobility particle sizer (FMPS)

Nanoparticle analyser which gives aerosol profiling of number concentration as a function of particle size distribution and time, allowing to monitor dynamic processes in workplace settings.

Term: Fate

Definition: Pattern of distribution of an agent, its derivatives or metabolites in an organism, system, compartment or population of concern as a result of transport, partitioning, transformation or degradation.

Term: Fecundity

Definition: The physiological reproductive capacity of an organism or population, i.e. its potential ability to produce viable offspring. Not to be confused with fertility.

Source: GreenFacts Glossary

Term: Fertility

Definition: The ability of people or animals to produce healthy offspring in abundance. Unlike fecundity, which measures a potential ability, fertility measures the actual number of offspring of an individual, a couple, a group or a population. It is evaluated by the time to achieve pregnancy.

Source: GreenFacts Glossary

Term: Few-layer graphene (FLG)

Definition:A subset of multi-layer graphene (defined as above) with layer numbers from 2 to about 5.

Source: Bianco et al. (2013)

Term: Fibrosis

Definition: Abnormal formation of fibrous tissue.

Source: NLM Toxicology Glossary

Term: Field flow fractionation (FFF)

Separation technique where a field is applied to a liquid suspension passing along a narrow channel in order to cause separation of the particles present in the liquid, dependent on their differing mobility under the force exerted by the field.

Source: ISO/TS 80004-6:2013

Term: Fine particles

Definition: Particulate matter present in air is divided into different categories depending on the size of the particles (aerodynamic diameter).

Term: Fluorescence correlation spectroscopy (FCS)

Spectroscopy using a correlation analysis of the fluctuation in the fluorescence intensity.

Source: ISO/TS 80004-6:2013

Term: Fluorescence

Phenomenon in which absorption of light of a given wavelength by a substance is followed by the emission of light at a longer wavelength.

Source: ISO 18115‑2:2010

Term: Fluorescence microscopy

Method of optical microscopy in which fluorescence emitted by the sample is imaged.

Source: ISO/TS 80004-6:2013

Term: Fluorescence spectroscopy

Spectroscopy of emitted light from a substance that has been illuminated.

Source: ISO/TS 80004-6:2013

Term: Foci (singular focus)

Definition: Small groups of cells distinguishable, in appearance or histochemically, from the surrounding tissue: indicative of an early stage of a lesion that may lead to the formation of a neoplastic nodule.

Source: NLM Toxicology Glossary

Term: Fourier transform infrared spectroscopy (FTIR)

An alalytical technique, based on spectroscopy, in which a sample is subjected to excitation of molecular bonds by pulsed, broad-band infra-red radiation, and the Fourier transform mathematical method is used to obtain an absorption spectrum.

Source: ISO 13943:2017

Term: Free radical

Definition: A free radical is an atom or molecule that is highly reactive because it contains an unpaired electron in the outer shell. Free radicals are formed as necessary intermediates in a variety of normal biochemical reactions, but can damage important cellular molecules such as DNA or lipids. Radicals can have positive, negative or neutral charge.

Source: GreenFacts Glossary

Term: Fullerene

Molecule composed solely of an even number of carbon atoms, which form a closed cage-like fused-ring polycyclic system with 12 five-membered rings and the rest six-membered rings.

Source: ISO/TS 80004-1:2015

Term: Gastrointestinal (GI)

Definition: Pertaining or communicating with the stomach and intestine.

Term: Gavage

Definition: Administration of materials directly into the stomach by oesophageal intubation.

Term: Gene

Definition: This is the part of the DNA molecule which carries the information defining the sequence of amino-acids in a specific polypeptide chain.

Term: Gene Expression

Definition: The process by which a gene is "turned on" to produce the specific biological molecule encoded by that gene (usually protein or RNA).

Source: GreenFacts Glossary

Term: Genetic toxicology (genotoxicology)

Definition: The study of chemicals which can cause harmful heritable changes in the genetic information carried by living organisms in the form of DNA.

Term: Genome

Definition: The general term for all the genes carried by a cell.

Term: Genotoxic

Definition: Toxic (damaging) to DNA. Substances that are genotoxic may bind directly to DNA or act indirectly leading to DNA damage by affecting enzymes involved in DNA replication, thereby causing mutations which may or may not lead to cancer or birth defects (inheritable damage). Genotoxic substances are not necessarily carcinogenic.

Source: GreenFacts Glossary

Term: Genotoxicity assay

Definition: A testing method to detect, quantify and characterise the DNA damage induced by a substance under investigation. These methods are indicators for likely carcinogenic agents.

Term: Glutathione (GSH)

Definition: Glutathione is a molecule consisting of 3 amino acids that is produced in the liver. In addition to assuring the smooth functioning of metabolic processes, it has a protective role in the cells of humans and of most animal and plant. Glutathione is an important antioxidant, meaning that it can bind to toxic substances and lead to their excretion from the body through urine or bile.

Source: GreenFacts Glossary

Term: Good Laboratory Practice (GLP)

Definition: Fundamental rules incorporated in national regulations concerned with the process of effective organisation and the conditions under which laboratory studies are properly planned, performed, monitored, recorded, and reported.

Source: NLM Toxicology Glossary

Term: Good Manufacturing Practice (GMP) Principles

Definition: Fundamental rules incorporated in national regulations concerned with the process of effective organisation of production and ensuring standards of defined quality at all stages of production, distribution and marketing; minimisation of waste and its proper disposal are part of this process.

Term: Granuloma

Definition: Granular growth or tumour, usually of lymphoid and epithelial cells.

Source: NLM Toxicology Glossary

Term: Graphene

Definition: Single layer of carbon atoms with each atom bound to three neighbours in a honeycomb structure.

Source: ISO/TS 80004-3:2010

Term: Graphene layer

Definition: A single-atom-thick sheet of hexagonally arranged, sp²-bonded carbon atoms occurring within a carbon material structure, regardless of whether that material structure has 3D order (graphitic) or not (turbostratic or rotationally faulted). The ‘‘graphene layer’’ is a conceptual structural unit that has been used for many years to describe the structure and texture of 3D carbon materials with primary sp²-hybridised bonding.

Source: Bianco et al. (2013)

Term: Graphene materials

Definition: Overarching term for the collection of 2D materials that contain the word ‘‘graphene’’, including multilayered materials (N less than about 10), chemically modified forms (GO, rGO), and materials made using graphene, graphene oxide, or another graphene material as a precursor.

Source: Bianco et al. (2013)

Term: Graphene microsheet

Definition: A single-atom-thick sheet of hexagonally arranged, sp²-bonded carbon atoms that is not an integral part of a carbon material, but is freely suspended or adhered on a foreign substrate and has a lateral dimension between 100 nm and 100 µm. This term is recommended over the more general ‘‘graphene’’, when one wants to emphasise the micrometer scale of the lateral dimension in cases where it is key to properties or behaviours.

Source: Bianco et al. (2013)

Term: Graphene nanoribbon

Definition: A single-atom-thick strip of hexagonally arranged, sp²-bonded carbon atoms that is not an integral part of a carbon material, but is freely suspended or adhered on a foreign substrate. The longer lateral dimension should exceed the shorter lateral dimension by at least an order of magnitude to be considered a ribbon, and the shorter lateral dimension (width) should be less than 100 nm to carry the prefix ‘‘nano’’.

Source: Bianco et al. (2013)

Term: Graphene nanosheet

Definition: A single-atom-thick sheet of hexagonally arranged, sp²-bonded carbon atoms that is not an integral part of a carbon material, but is freely suspended or adhered on a foreign substrate and has a lateral dimension less than 100 nm. ‘‘Graphene nanosheet’’ is now commonly used in the literature to refer to all graphene materials, but ‘‘nano’’ is not needed here as all ‘‘graphene’’ samples are very thin. That use of ‘‘graphene nanosheet’’ is not recommended as it interferes with its more logical use to describe the important subset of graphene materials with lateral dimension in the nanoscale (<100 nm).

Source: Bianco et al. (2013)

Term: Graphene oxide

Definition: Chemically modified graphene prepared by oxidation and exfoliation that is accompanied by extensive oxidative modification of the basal plane. Graphene oxide is a monolayer material with a high oxygen content, typically characterised by C/O atomic ratios less than 3.0 and typically closer to 2.0.

Source: Bianco et al. (2013)

Term: Graphene quantum dots (GQDs)

Definition: An alternative term for graphene nanosheets or few-layer graphene nanosheets, which is used particularly in studies where photoluminescence is the target property. Generally, GQDs have very small lateral dimensions <10 nm (average 5 nm) at the lower end of the range for graphene nanosheets, which is <100 nm lateral dimension. Some GQDs may be fewlayer materials.

Source: Bianco et al. (2013)

Term: Graphenic carbon materials

Definition: The broadest class of carbonaceous solids that consist primarily of elemental carbon bonded through sp²-hybridisation. Graphenic carbon materials, or ‘‘graphenic materials’’, include the 2D forms described in this article (graphene materials, as above), as well as 3D forms whose structures are based on the ‘‘graphene layer’’ as the conceptual structural unit, including activated carbons, carbon fibers, chars, cokes, and bulk graphite.

Source: Bianco et al. (2013)

Term: Graphenisation

Definition: The development, growth, or perfection of graphene layers during the processing of disordered carbonaceous solids. The graphene layers may occur within a 2D (sheet-like) or 3D carbon material. A related term is ‘‘carbonisation’’, which refers to the primary conversion of organic material into a carbonaceous solid - one consisting primarily of elemental carbon - regardless of structure. Also related is ‘‘graphitisation’’, which refers to the development of 3D crystalline order including defined ABA or ABCA graphene layer registry, which typically appears only in the later stages of order development. In some cases, graphenisation may occur after carbonisation as a distinct process of solid-state rearrangement leading to the loss of amorphous material and appearance of well-defined graphene layers. In other cases, graphene layers may grow directly from the gas or melt phase without undergoing separate identifiable stages of carbonisation and graphenisation.

Source: Bianco et al. (2013)

Term: Graphite

Definition: Allotropic form of the element carbon, consisting of graphene layers stacked parellel to each other in a three dimensional, crystalline, long-range order.

Source: ISO/TS 80004-3:2010

Term: Graphite nanofibre

Definition: Carbon nanofibre composed of graphene multilayer structures.

Source: ISO/TS 80004-3:2010

Term: Graphite nanoplates; graphite nanosheets; graphite nanoflakes

Definition: 2D graphite materials with ABA or ABCA stacking, and having a thickness and/or lateral dimension less than 100 nm. The use of nanoscale terminology here can be used to help distinguish these new ultrathin forms from conventional finely milled graphite powders, whose thickness is typically >100 nm. An acceptable alternative term is ‘ultrathin graphite’’, though ‘‘ultra’’ is less specific than ‘‘nano’’ in describing the maximum thickness.

Source: Bianco et al. (2013)

Term: Graphite oxide

Definition: A bulk solid made by oxidation of graphite through processes that functionalise the basal planes and increase the interlayer spacing. Graphite oxide can be exfoliated in solution to form (monolayer) graphene oxide or partially exfoliated to form few-layer graphene oxide.

Source: Bianco et al. (2013)

Term: Grinding

Definition: Creation of nanoparticles via mechanical shearing in contact with a material of greater hardness.

Source: ISO/TS 80004-8:2013

Term: Half-life

Definition: Time required for the concentration of a reactant in a given reaction to reach a value that is the arithmetic mean of its initial and final (equilibrium) values. For a reactant that is entirely consumed it is the time taken for the reactant concentration to fall to one half of its initial value.
Note: The half life of a reaction has meaning only in special cases:

1. For a first-order reaction, the half life of the reactant may be called the half life of the reaction.

2. For a reaction involving more than one reactant, with the concentrations of the reactants in their stoichiometric ratios, the half life of each reactant is the same, and may be called the half life of the reaction.

If the concentrations of reactants are not in their stoichiometric ratios, there are different half lives for different reactants, and one cannot speak of the half life of the reaction.

Source: NLM Toxicology Glossary

Term: Harm

Definition: Damage or adverse effect to a population, species, individual organism, organ, tissue or cell.

Term: Hazard

Definition: Inherent property of an agent or situation having the potential to cause harm when an organism, system or population is exposed to that agent.

Term: Hazard Assessment

Definition: A process designed to determine the probable adverse effects of an agent or situation to which an organism, system or population could be exposed.The process includes hazard identification and hazard characterization.

Term: Hazard Characterization

Definition: The qualitative and or quantitative description of the inherent properties of an agent or situation having the potential to cause adverse effects. This should, where possible, include a dose-response assessment and its attendant uncertainties.

Term: Hazard Identification

Definition: The identification of the type and nature of adverse effects that an agent has as inherent capacity to cause in an organism, system or population. Hazard identification is the first stage in hazard assessment and the first step in the process of risk assessment.

Term: Heavy metal

Definition: Erroneous terms used commonly in the toxicological literature but having no generally agreed meaning, sometimes even applied to nonmetals, and therefore a source of confusion and to be avoided. The term "metal" is adequate without the qualifying adjective but may be misleading since it implies a solid material when toxicological concern is mostly for the ionic form or another chemical species.

Source: NLM Toxicology Glossary

Term: Hepatic

Definition: Pertaining to the liver.

Source: NLM Toxicology Glossary

Term: Hepatitis

Definition: Inflammation of the liver caused by viruses (viral hepatitis) or by chronic exposure to medicines or toxins such as alcohol.

Term: Hepatocyte

Definition: In histology, this name is given to a parenchymal liver cell.

Term: Hepatotoxic

Definition: Poisonous to liver cells.

Source: NLM Toxicology Glossary

Term: Herbicide

Definition: Any chemical substance designed to kill or inhibit the growth of certain plants that are considered undesirable.

Term: High aspect ratio nanoparticle (HARN)

A nanoparticle with a high aspect ratio (i.e. high ratio of length to width). Examples include nanotubes and nanorods.

Term: Histology

Definition: This is the science concerned with the study of the microanatomy of tissues and their cellular structure.

Term: Histopathology

Definition: This is the science concerned with the study of microscopic changes in diseased tissues.

Term: Homeostasis

Definition: In medicine and biology, this term is applied to the inherent tendency in an organism toward maintenance of physiological and psychological stability.

Term: HSE

Definition: The UK Health and Safety Executive. The HSE web site can be reached through The HSE is responsible for proposing and enforcing safety regulations throughout UK industry and academia. Publications are available on a wide variety of safety-related issues.

Term: Hydrodynamic diameter

Definition: Equivalent diameter of a particle in a liquid having the same diffusion coefficient as the real particle in that liquid.

Source: ISO/TS 80004-6:2013

Term: Hydrophilic

Definition: Describing the character of a molecule or atomic group which has an affinity for water.

Term: Hydrophobic

Definition: Describing the character of a molecule or atomic group which is insoluble in water, or resistant to wetting or hydration.

Term: Hyperplasia

Definition: Abnormal multiplication or increase in the number of normal cells in a tissue or organ.

Term: Hypertrophy

Definition: Excessive growth in bulk of a tissue or organ through increase in size but not in number of the constituent cells.

Term: Immune response

Definition: The immune response is the general reaction of the body to substances that are foreign or treated as foreign. It may take various forms e.g. antibody production, cell-mediated immunity, immunological tolerance, or hypersensitivity (allergy).

Term: Immune system

Definition: The immune system is a network of cells, tissues, and organs that work together to defend the body against attacks by "foreign" invaders.

Term: Immunosuppressive

Definition: A process or substance, such as a drug, a hormone or a virus, that reduces the functioning of the immune system, lowering the body’s ability to fight infection.

Term: Immunotoxic

Definition: Any substance harmful to the immune system.

Term: In vitro

Definition: A term applied to any study carried out in isolation from the living organism in an experimental system (literally in glass).

Term: In vivo

Definition: A study carried out within a living organism.

Term: Incidental nanomaterial

Definition: Nanomaterial generated as an unintentional by-product of a process.

Source: ISO/TS 80004-1:2015

Term: Indirect exposure

Definition: 1. Exposure to a substance in a medium or vehicle other than the one originally receiving the substance

Term: Inductively coupled plasma mass spectrometry (ICPMS)

Definition: Method in which a high-temperature discharge generated in flowing argon by an alternating magnetic field induced by a radio-frequency (RF) load coil that surrounds the tube carrying the gas is detected using a mass spectrometer.

Source: ISO 15202‑3:2004

Term: Inflammation

Definition: Inflammation is the reaction of living tissues to infection, irritation or other injury.

Term: Inhalable fraction

Definition: Particle mass with a median aerodynamic diameter of 100 μm collected with 50% efficiency. Particles within the inhalable fraction can enter the nose or mouth upon inhalation.

Term: Inhibitory dose (ID)

Definition: Dose of a substance that causes a defined inhibition of a given system: ID50 is the median dose that causes 50% inhibition.

Source: NLM Toxicology Glossary 

Term: Intermediate duration exposure

Definition: Contact with a substance that occurs for more than 14 days and less than a year [for humans].

Source: ATSDR Glossary of Terms

Term: Ion beam analysis

Definition: Method to elucidate composition and structure of the outermost atomic layers of a solid material, in which principally mono-energetic, singly charged probe ions, scattered from the surface are detected and recorded as a function of their energy or angle of scattering, or both.

Term: Irritant

Definition: This descriptor is applied to any substance causing inflammation following immediate, prolonged, or repeated contact with skin or mucous membrane.

Term: Isomer

Definition: A chemical compound that has the same molecular formula - the same number and kinds of atoms - as another compound, but a different structural arrangement of the atoms in space, and, therefore, different properties. For example, graphite (pencil lead) and diamond are isomers of carbon. Both are composed of pure carbon, but have very different physical properties.

Term: Latent period

Definition: Delay between exposure to a disease-causing agent and the appearance of manifestations of the disease: also defined as the period from disease initiation to disease detection.

Term: Lavage

Definition: Irrigation or washing out of a hollow organ or cavity such as the stomach, intestine or the lungs.

Term: Lesion

Definition: 1. Area of pathologically altered tissue.
2. Injury or wound.
3. Infected patch of skin.

Term: Lethal Dose (LD)

Definition: Amount of a substance or physical agent (radiation) that causes death when taken into the body by a single absorption (denoted by LD). LD50 is the amount of a chemical that is lethal to one-half (50%) of the experimental animals exposed to it. LD50s are usually expressed as the weight of the chemical per unit of body weight (mg/kg). It may be fed (oral LD50), applied to the skin (dermal LD50), or administered in the form of vapours (inhalation LD50).

Term: Life Cycle Assessment (LCA)

Definition: Process of comparing the environmental performance of products or services, to enable an informed choice. The term 'life cycle' refers to the notion that a fair assessment must consider all steps from cradle to grave: raw material production, processing, use and disposal, and transportation.

Term: Light scattering

Definition: Change in propagation of light at the interface of two media having different optical properties.

Source: ISO 16014-1:2012

Term: Limit test

Definition: Acute toxicity test in which, if no ill-effects occur at a pre-selected maximum dose, no further testing at greater exposure levels is required.

Term: Linearised multistage model

Definition: Sequence of steps in which (a) a multistage model is fitted to tumour incidence data; (b) the maximum linear term consistent with the data is calculated; (c) the low-dose slope of the dose-response function is equated to the coefficient of the maximum linear term; and (d) the resulting slope is then equated to the upper bound of potency.

Term: Lipid

Definition: An essential structural component of living cells, lipids are a class of oily organic compounds which are insoluble in water but soluble in fats and oils. The lipid class of molecules mainly consists of fats, oils and waxes.

Source: GreenFacts Glossary

Term: Lipophilic

Definition: Having an affinity for fat and high lipid solubility: a physicochemical property which describes a partitioning equilibrium of solute molecules between water and an immiscible organic solvent, favouring the latter, and which correlates with bioaccumulation.

Source: NLM Toxicology Glossary

Term: Lipophobic

Definition: Having a low affinity for fat and a high affinity for water.

Source: NLM Toxicology Glossary

Term: Lipoproteins

Definition: Molecules that are a combination of fat and protein and that transports fats and fat-like substances, such as cholesterol, in the blood.

Source: GreenFacts Glossary

Term: Lithography

Definition: Reproducible creation of a pattern.

Source: ISO/TS 80004-8:2013

Term: Lorentz microscopy

Definition: Type of transmission electron microscopy using the interaction of the electron beam with the magnetic induction of a nanoscale structure to create an image of the magnetic structure of a sample.

Source: Nanocharm Glossary of Terms

Term: Low energy electron microscopy (LEEM)

Definition: Method that examines surfaces where images and/or diffraction patterns of the surfaces are formed by low-energy elastically backscattered electrons generated by a non-scanning electron beam.

Source: ISO/TS 80004-6:2013

Term: Lowest Observed Adverse Effect Level (LOAEL)

Definition: The lowest tested dose of a substance that has been reported to cause harmful (adverse) health effects on people or animals. Can apply to a particular study, species (e.g. rat, dog), or all studies on a particular substance. The difference between LOAEL and LOEL rests on the definition of adverse effect only, that is, an experimental study that produced a LOAEL will have stated the adverse effect to be observed before initiation.

Source: ATSDR Glossary of Terms

Term: Lowest Observed Effect Level (LOEL)

Definition: Lowest concentration or amount of a substance, found by experiment or observation, which causes an adverse alteration of morphology, functional capacity, growth, development, or life span of a target organism distinguishable from normal (control) organisms of the same species and strain under defined conditions of exposure.

Source: NLM toxicology Glossary

Term: Lymphatic system

Definition: The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases. This system includes the bone marrow, spleen, thymus, lymph nodes (small glands found along the vessels of the lymphatic system that filter out bacteria and other toxins, as well as cancer cells), and lymphatic vessels (a network of thin tubes that carry lymph and white blood cells). Lymphatic vessels branch, like blood vessels, into all the tissues of the body.

Term: Lymphocyte

Definition: Animal cell that interacts with a foreign substance or organism, or one which it identifies as foreign, and initiates an immune response against the substance or organism. There are two groups of lymphocytes, B lymphocytes and T lymphocytes.

Source: NLM Toxicology Glossary

Term: Lysimeter

Definition: Laboratory column of selected representative soil or a protected monolith of undisturbed field soil with facilities for sampling and monitoring the movement of water and chemicals.

Term: Lysosome

Definition: Membrane-bound cytoplasmic organelle containing hydrolytic enzymes.

Source: NLM Toxicology Glossary

Term: Mössbauer spectroscopy

Definition: Recoil-free nuclear emission and resonant absorption of gamma radiation.

Source: ISO 921:1997

Term: Macrophage

Definition: Large phagocytic cells found in connective tissue, especially in areas of inflammation.

Term: Magnetic Resonance Force Microscopy (MRFM)

Definition: Scanning probe method which combines the three-dimensional imaging capabilities of magnetic imaging with the high sensitivity and resolution of atomic force microscopy by mechanically detecting magnetic resonance signals between a permanent magnet and the spin magnetization of the atoms.

Term: Magnetic Resonance Imaging (MRI)

Definition: Technique that uses a strong circular magnet in combination with pulses of radio waves to produce detailed images of internal organs. MRI is especially useful for imaging spine, joints, and inside bones and also soft tissue such as the brain. Physicians can use MRI to see for instance the difference between normal and diseased brain tissue or which parts of the brain are active when you perform certain tasks or feel certain emotions and sensations. MRI is one of several Nuclear Magnetic Resonance techniques.

Source: GreenFacts Glossary

Term: Magnetic Resonance Spectroscopy (MRS)

Definition: A technique that uses a strong circular magnet for instance to identify the chemical composition of diseased tissue. MRS is one of several Nuclear Magnetic Resonance techniques. It is somewhat different from MRI because it uses a continuous band of radio wave frequencies to excite hydrogen atoms. Physicians mainly use MRS to study the brain and disorders such as epilepsy, Alzheimer's disease, brain tumours, and the effects of drugs on brain growth and metabolism. The technique is also useful in evaluating metabolic disorders of the muscles and nervous system.

Source: GreenFacts Glossary

Term: Malignant

Definition: Adjective describing cells in a cancerous growth. See tumour.

Term: Manufactured nanomaterial

Nanomaterial intentionally produced for commercial purposes to have specific properties or specific composition.

Source: ISO/TS 80004-1:2010

Term: Mass mean diameter

Definition: Diameter of a particle with a mass equal to the mean mass of all the particles in a population.

Source: NLM Toxicology Glossary

Term: Mass median diameter

Definition: Diameter of a particle with the median mass of all the particles in a population.

Source: NLM Toxicology Glossary

Term: Mass specific surface area

Definition: Absolute surface area of the sample divided by sample mass.

Source: ISO 9277:2010

Term: Maximum Permissible Concentration (MPC)

Definition: Occupational exposure limit legally defined in GB under COSHH as the maximum concentration of an airborne substance, averaged over a reference period, to which employees may be exposed by inhalation under any circumstances, and set on the advice of the HSC Advisory Committee on Toxic Substances.

Source: NLM Toxicology Glossary

Term: Maximum tolerable dose (MTD)

Definition: Highest concentration of a substance in an environmental medium that does not cause death of test organisms or species (denoted by LCo).

Source: NLM Toxicology Glossary 

Term: Mesothelioma

Definition: Malignant spreading tumour of the mesothelium of the pleura, pericardium, or peritoneum, arising primarily as a result of the presence of asbestos fibres.

Term: Meta-analysis

Definition: A statistical method of combining the results of a number of different studies in order to provide a larger sample size for evaluation and to produce a stronger conclusion than can be provided by any single study.

Source: GreenFacts Glossary

Term: Metabolism

Definition: Sum of the physical and chemical changes that take place in living organisms. These changes include both synthesis (anabolism) and breakdown (catabolism) of body constituents. In a narrower sense, the physical and chemical changes that take place in a given chemical substance within an organism. It includes the uptake and distribution within the body of chemical compounds, the changes (biotransformations) undergone by such substances, and the elimination of the compounds and their metabolites.

Term: Metabolite

Definition: A substance that is the product of biological changes to a chemical.

Source: US EPA Drinking Water Glossary

Term: Metastasis

Definition: 1. Movement of bacteria or body cells, especially cancer cells, from one part of the body to another, resulting in change in location of a disease or of its symptoms from one part of the body to another
2. Growth of pathogenic micro-organismsor of abnormal cells distant from the site of their origin in the body.

Source: NLM Toxicology Glossary

Term: Methylation

Definition: Addition of a methyl group to a molecule or atom, often through bacterial action.

Source: GreenFacts Glossary

Term: Microencapsulation

Definition: Individually encapsulated small particles.

Term: Micrometre

Definition: Unit of length equal to one millionth of a metre.

Source: GreenFacts Glossary

Term: Micro-organism

Definition: Any living organism that is too small to be seen by the naked eye such as bacteria, viruses, protozoa, single-celled algae, and many types of fungi.

Term: Molecule

Definition: A molecule is the smallest part of any chemical compound composed of two or more atoms and which has the qualities of that substance and can exist alone in a free state. As an example, a molecule of water (H2O) consists of two atoms of hydrogen and one of oxygen.

Source: GreenFacts Glossary

Term: Morbidity

Definition: A disease or the incidence of a disease within a population.

Source: GreenFacts Glossary

Term: Mortality

Definition: Death. Usually the cause (a specific disease, a condition, or an injury) is stated.

Source: ATSDR Glossary of Terms

Term: Mortality rate

Definition: A measure of frequency of occurrence of death in a defined population during a specified interval of time.

Source: CDC Reproductive Health Glossary

Term: Mucous membrane

Definition: The moist layer of tissue lining the digestive, respiratory, urinary and reproductive tracts - all the body cavities with openings to the outside world except the ears.

Term: Multi-layer graphene (MLG)

Definition: A 2D (sheet-like) material, either as a free-standing flake or substrate-bound coating, consisting of a small number (between 2 and about 10) of well-defined, countable, stacked graphene layers of extended lateral dimension. If the stacking registry is known it can be specified separately, such as ‘‘ABA-stacked multi-layer graphene’’, ‘‘Bernal-stacked multi-layer graphene’’ or ‘‘rotationally faulted multi-layer graphene’’. Carbon films containing discontinuous or fragmented graphene layers of very small lateral dimension should be called ‘‘carbon thin films’’ rather than ‘‘multi-layer graphene’’, since they do not consist of a defined number of countable graphene layers of extended lateral dimension.

Source: Bianco et al. (2013)

Term: Multi-wall carbon nanotube (MWCNT)

Definition: Carbon nanotube composed of nested, concentric or near-concentric graphene sheets with interlayer distances similar to those of graphite.

Source: ISO/TS 80004-3:2010

Term: Mutagen

Definition: Agent causing mutations.

Term: Mutation

Definition: Any permanent change in the DNA of a cell.

Mutations may be caused by mistakes during cell division, or they may be caused by exposure to DNA-damaging agents in the environment. Mutations can be harmful, beneficial, or have no effect. If they occur in cells that make eggs or sperm, they can be inherited; if mutations occur in other types of cells, they are not inherited. Certain mutations may lead to cancer or other diseases.

Source: NCI Dictionary of Cancer Terms

Term: Nanobiotechnology

Definition: Application of nanoscience or nanotechnology to biology or biotechnology.

Source: ISO/TS 80004-5:2011

Term: Nanocarrier

Definition: Nano-object or objects, which are at a larger scale but which carry nanoscale payloads able to transport a diagnostic or therapeutic agent either on its surface, within its bulk structure or within an internal cavity.

Source: ISO/TS 80004-7:2011

Term: Nanoclay

Definition: Nanoclays are nanoparticles of layered mineral silicates. Depending on chemical composition and morphology, nanoclays are organised into several classes such as montmorillonite, bentonite, kaolinite, hectorite, and halloysite. Organically-modified nanoclays (organoclays) are an attractive class of hybrid organic-inorganic nanomaterials with potential uses in polymer nanocomposites.

Source: Sigma-Aldrich

Term: Nanocomposite

Definition: Solid comprising a mixture of two or more phase-separated materials, one or more being nanophase.

Source: ISO/TS 80004-4:2011

Term: Nanocone

Definition: Cone-shaped nanofibre or nanoparticle.

Source: ISO/TS 80004-3:2010

Term: Nanodispersion

Definition: Material in which nano-objects or a nanophase are dispersed in a continuous phase of a different composition.

Source: ISO/TS 80004-4:2011

Term: Nanoelectronics

Definition: Electronics on a nanometre scale, whether made by current techniques or nanotechnology; includes both molecular electronics and nanoscale devices resembling today's semiconductor devices.

Source: Institute of Nanotechnology Glossary

Term: Nanofabrication

Definition: Ensemble of activities, to intentionally manufacture devices in the nanoscale, for commercial purpose.

Source: ISO/TS 80004-8:2013

Term: Nanofibre

Definition: A nano-object with two similar external dimensions in the nanoscale and the third dimension significantly larger.

Term: Nanofoam

Definition: Liquid or solid matrix, filled with a second, gaseous phase, typically resulting in a material of much lower density with a nanostructured matrix, for example having nanoscale struts and walls, or a gaseous nanophase consisting of nanoscale bubbles (closed nanofoam), or both.

Source: ISO/TS 80004-4:2011

Term: Nanomanufacturing

Definition: Intentional synthesis, generation or control of nanomaterials, or fabrication steps in the nanoscale, for commercial purposes.

Source: ISO/TS 80004-1:2010

Term: Nanomanufacturing process

Definition: Ensemble of activities to intentionally synthesise, generate or control nanomaterials, or fabrication steps in the nanoscale, for commercial purposes.

Source: ISO/TS 80004-1:2010

Term: Nanomaterial

Definition: Material with any external dimension in the nanoscale or having internal structure or surface structure in the nanoscale.

Source: ISO/TS 80004-1:2010

Term: Nanometre

Definition: Unit of length equal to one millionth of a millimetre (10-9 m).

Term: Nano-object

Definition: Material with one, two or three external dimensions in the nanoscale. Generic term for all discrete nanoscale objects.

Source: British Standards Institute, ISO/TS 27687

Term: Nano-onion

Spherical nanoparticle with concentric multiple shell structure.

Source: ISO/TS 80004-3:2010

Term: Nano-optics

Definition: Interaction of light and matter on the nanoscale.

Source: Institute of Nanotechnology Glossary

Term: Nanoparticle

Definition: A nano-object with all three external dimensions in the nanoscale.

Source: ISO/TS 27687

Term: Nanoparticle dispersion

Definition: Creating a suspension of nanoparticles in a liquid through molecular ligands, surface charges or other interactions to prevent or slow sedimentation.

Source: ISO/TS 80004-8:2013

Term: Nanoparticle tracking analysis (NTA)

Definition: Method where particles undergoing Brownian motion in a liquid suspension are illuminated by a laser and the change in position of individual particles is used to determine particle size.

Source: ISO/TS 80004-6:2013

Term: Nanoparticle surface area monitor (NSAM)

Definition: Instrument which uses diffusion charging to provide information on the lung deposited surface area (LDSA) of an aerosol.

Term: Nanophase

Definition: Physically or chemically distinct region or collective term for physically distinct regions of the same kind in a material with the discrete regions having one, two or three dimensions in the nanoscale.

Source: ISO/TS 80004-4:2011

Term: Nanoplate

Definition: A nano-object with one external dimension in the nanoscale and the two other external dimensions significantly larger.

Source: ISO/TS 27687

Term: Nanopore

Definition: Cavity with at least one dimension in the nanoscale, which may contain a gas or liquid.

Source: ISO/TS 80004-4:2011

Term: Nanoribbon

Definition: Nanoplate with one of its two larger dimensions in the nanoscale and the other significantly larger.

Source: SO/TS 80004-3:2010

Term: Nanorod

Definition: A solid nanofibre.

Source: ISO/TS 27687

Term: Nanoscale

Definition: Size range from approximately 1 nm to 100 nm.

Source: ISO/TS 27687

Term: Nanoscale phenomenon

Definition: Effect attributable to nano-objects or nanoscale regions.

Source: ISO/TS 80004-1:2010

Term: Nanoscale property

Definition: Characteristic of a nano-object or nanoscale region.

Source: ISO/TS 80004-1:2010

Term: Nanoscience

Definition: Study, discovery and understanding of matter in the nanoscale, where size- and structure-dependent properties and phenomena, as distinct from those associated with individual atoms or molecules or with bulk materials, can emerge.

Source: ISO/TS 80004-1:2010

Term: Nanostructure

Definition: Composition of inter-related constituent parts, in which one or more of those parts is a nanoscale region.

Source: ISO/TS 80004-1:2010

Term: Nanostructured material

Definition: Material having internal nanostructure or surface nanostructure.

Source: ISO/TS 80004-1:2010

Term: Nanotechnology

Definition: Application of scientific knowledge to manipulate and control matter in the nanoscale in order to make use of size- and structure-dependent properties and phenomena, as distinct from those associated with individual atoms or molecules or with bulk materials.

Source: ISO/TS 80004-1:2010

Term: Nanotoxicology

Definition: Application of toxicology to the study of nanomaterials.

Source: ISO/TS 80004-5:2011

Term: Nanotube

Definition: A hollow nanofibre.

Source: ISO/TS 27687

Term: Nanowire

Definition: Electrically conducting or semi-conducting nanofibre.

Source: ISO/TS 27687

Term: Natural Organic Matter (NOM)

Definition: Organic matter originating from plants and animals present in natural (untreated or raw) waters, for example, in lakes, rivers and reservoirs.

Source: GreenFacts Glossary

Term: Near edge x-ray absorption fine structure (NEXAFS)

Definition: Method that uses measurement of the energies of photons and electrons emitted from matter following irradiation with x-ray photons, which themselves have energies close to the absorption edge of the material, to derive structural information about the irradiated material.

Source: Nanocharm Glossary of Terms

Term: Near field scanning optical microscopy (NSOM)

Definition: Method of imaging surfaces optically in transmission or reflection by mechanically scanning an optically active probe much smaller than the wavelength of light over the surface whilst monitoring the transmitted or reflected light or an associated signal in the near-field regime.

Source: ISO 18115‑2:2010

Term: Necrosis

Definition: Mass death of areas of tissue surrounded by otherwise healthy tissue.

Term: Neoplasm

Definition: New and abnormal formation of tissue as a tumour or growth by cell proliferation that is faster than normal and continues after the initial stimulus that initiated the proliferation has ceased.

Source: NLM Toxicology Glossary

Term: Nervous system

Definition: The nervous system is a complex, sophisticated system that regulates and coordinates body activities.

Term: Neurological Effects

Definition: Effects to nervous system especially regarding structure, functions, and abnormalities.

Source: GreenFacts Glossary

Term: Neuromuscular

Definition: Of, or relating to, nerves and the muscles they stimulate.

Source: GreenFacts Glossary

Term: Neuron

Definition: Neurons are the nerve cells that make up the central nervous system. This unique type of cell found in the brain receives and conducts electric impulses, processes and transmits information. A neuron consists of a cell body containing the nucleus, a single axon which sends messages by conveying electrical signals to other neurons, and a host of dendrites which deliver incoming signals.

Source: GreenFacts Glossary

Term: Neurotoxic

Definition: Able to produce chemically an adverse effect on the nervous system. Such effects may be subdivided into two types:

Term: Neurotransmitter

Definition: Chemical responsible for the transfer of information along the nervous system.

Source: GreenFacts Glossary

Term: No observed effect level (NOEL)

Definition: This is the greatest concentration or amount of a chemical found by experiment or observation that causes no detectable adverse alteration of morphology, functional capacity, growth, development, or life span of the target organism. The maximum dose or ambient concentration which an organism can tolerate over a specified period of time without showing any detectable adverse effect and above which adverse effects are apparent.

Term: Non-linearity

Definition: A non-linear change is a change that is not based on a simple proportional relationship between cause and effect. Therefore, such changes are often abrupt, unexpected, and difficult to predict.

Source: GreenFacts Glossary

Term: NPS

Definition: Instrument that uses electrical mobility to measure number and surface area distributions on an aerosol, and to calculate volume and mass distributions.

Term: Nuclear magnetic resonance (NMR) spectroscopy

Definition: Method where the resonance magnetic properties of atomic nuclei are used to determine physical and chemical properties of atoms and molecules.

Source: ISO/TS 80004-6:2013

Term: Nutrients

Definition: The approximately 20 chemical elements known to be essential for the growth of living organisms, including nitrogen, sulfur, phosphorus, and carbon.

Term: Occupational exposure

Definition: Experience of substances, intensities of radiation etc. or other conditions while at work.

Source: NLM Toxicology Glossary

Term: Occupational Exposure Limit (OEL)

Definition: Regulatory level of exposure to substances, intensities of radiation etc. or other conditions, specified appropriately in relevant government legislation or related codes of practice.

Term: Occupational Health

Definition: Occupational Health is a multi-disciplinary area concerned with protecting the safety, health and welfare of people engaged in work or employment. As a secondary effect Occupational Health may also protect co-workers, family members, employers, customers, suppliers, nearby communities, and other members of the public who may experience an impact from the workplace environment. Occupational Health is an area under development in the nanotechnology field.

Term: Occupational Hygiene

Definition: Occupational hygiene is the applied science concerned with the recognition, evaluation, and control of chemical, physical and biological factors arising in or from the workplace which may affect the health or well-being of those at work or in the community.

Term: Octanol-water partition coefficient (Kow)

Definition: Measure of lipophilicity by determination of the equilibrium distribution between octan-1-ol and water, as used in pharmacological studies and in the assessment of environmental fate and transport of organic chemicals.

Source: NLM Toxicology Glossary

Term: Optical spectroscopy

Definition: Spectroscopy where the radiation consists of electromagnetic radiation in the visible, ultraviolet or infrared wavelengths.

Source: ISO/TS 80004-6:2013

Term: Organelle

Definition: Any structure which occurs in cells and which has a specialized function.

Term: Organic

Definition: The term organic has different meanings (depending on the context):

In chemistry, "organic" refers to a chemical compound based on a hydrocarbon, i.e. a chain or a ring of carbon atoms onto which hydrogen atoms are bonded.

In agriculture, "organic" refers to a production system that excludes or limits the use of chemicals.

Term: Organophosphate pesticides

Definition: A group of organic compounds containing phosphorus that are used as insecticides.

Term: Oxidative phosphorylation

Definition: Process occurring in the cell, which produces energy and synthesises ATP (energy carrier of the body).

Term: Oxidative stress

Definition: An imbalance between the generation of harmful reactive oxygen species and the cells’ ability to neutralise these oxidants, resulting in damage to cellular components including proteins, lipids and DNA.

Source: N. Singh et al., Biomaterials (2009)

Term: Oxidising agent

Definition: Any substance, such as oxygen (O2) or chlorine (Cl2), that will readily accept electrons. The opposite is a reducing agent.

Term: Particle

Definition: Minute piece of matter with defined physical boundaries.

Source: ISO 14644‑6:2007 & ISO/TS 27687:2008

Term: Particle size

Definition: Linear dimension of a particle determined by a specified measurement method and under specified measurement conditions.

Source: ISO 26824:2013

Term: Particle shape

Definition: External geometric form of a particle.

Source: ISO 3252:1999

Term: Particle size distribution

Definition: Distribution of particles as a function of particle size.

Source: ISO 14644‑1:1999

Term: Particulate matter

Definition: Sum of all microscopic solid and liquid particles, of human and natural origin, that remain suspended in a medium such as air for some time. These particles vary greatly in size, composition, and origin, and may be harmful.

Particulate matter may be in the form of fly ash, soot, dust, fog, fumes etc.

Term: Particulate Matter (PM)

Definition: PM stands for particulate matter suspended in air. PM followed by a number refers to all particles with a certain maximum size (aerodynamic diameter). All smaller particles are included.

PM0.1 is particulate matter with an aerodynamic diameter of up to 0.1 µm, referred to as the ultrafine particle fraction.

PM2.5 is particulate matter with an aerodynamic diameter of up to 2.5 µm, referred to as the fine particle fraction (which per definition includes the ultrafine particles).

PM10 is particulate matter with an aerodynamic diameter of up to 10 µm, i.e. the fine and coarse particle fractions combined.

Source: GreenFacts Glossary

Term: Pathogenic organisms

Definition: Organisms, including bacteria, viruses or cysts, capable of causing diseases (typhoid, cholera, dysentery) in a host (such as a person). There are many types of organisms which do NOT cause disease. These organisms are called non-pathogenic.

Source: US EPA Drinking Water Glossary 

Term: Peptide

Definition: Any of various natural or synthetic compounds containing two or more amino acids linked by the carboxyl group of one amino acid to the amino group of another.

Source: Institute of Nanotechnology Glossary

Term: Percutaneous

Definition: Through the skin following application on the skin.

Source: NLM Toxicology Glossary

Term: Peritoneum

Definition: The tissue that lines the abdominal wall and covers most of the organs in the abdomen.

Source: NCI Dictionary of Cancer Terms

Term: Permissible exposure limit (PEL)

Definition: Recommendation by US OSHA for TWA concentration that must not be exceeded during any 8-hour work shift of a 40h working week.

Source: NLM Toxicology Glossary

Term: Persistence

Definition: Attribute of a substance that describes the length of time that the substance remains in a particular environment before it is physically removed or chemically or biologically transformed.

Source: NLM Toxicology Glossary

Term: Persistent organic pollutants

Definition: Persistent organic pollutants (POPs) are chemical substances that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the environment. This group of priority pollutants consists of pesticides (such as DDT), industrial chemicals (such as polychlorinated biphenyls, PCBs) and unintentional by-products of industrial processes (such as dioxins and furans).

Persistent Organic Pollutants are transported across international boundaries far from their sources, even to regions where they have never been used or produced.

Source: European Commission Environment DG

Term: Personal monitoring

Definition: Type of environmental monitoring in which an individual's exposure to a substance is measured and evaluated: this is normally carried out using a personal sampler.

Term: Personal protective equipment (PPE)

Definition: Equipment (clothing, gloves, hard hat, respirator and so on) worn by an individual to prevent exposure to a potentially toxic substance.

Term: Pesticide

Definition: A toxic chemical product that kills harmful organisms (e.g., insecticides, fungicide, weedicides, rodenticides, acaricides).

Source: FAO Glossary of biotechnology & genetic engineering

Term: pH

Definition: pH is a measure of the concentration of protons (H+) in a solution and, therefore, its acidity or alkalinity. The concept was introduced by S.P.L. Sørensen in 1909. The p stands for the German "Potenz", meaning power or concentration, and the H for the hydrogen ion (H+). In layman's terms , the "pH" value is an approximate number between 0 and 14 that indicates whether a solution is acidic (pH < 7), basic (pH > 7) or neither (pH = 7) [neutral].

Source: GreenFacts Glossary

Term: Phagocytosis

Definition: The ingestion of micro-organisms, cells, and foreign particles by phagocytes, e.g. phagocytic macrophages. See macrophages.

Term: Pharmacodynamics

Definition: Broadly, this is the science concerned with the study of the way in which xenobiotics exert their effects on living organisms. Such a study aims to define the fundamental physicochemical processes which lead to the biological effect observed. Synonym: toxicodynamics.

Term: Pharmacokinetics

Definition: This is the science which describes quantitatively the uptake of drugs by the body, their biotransformation, their distribution, metabolism, and elimination from the body. Both total amounts and tissue and organ concentrations are considered. "Toxicokinetics" is essentially the same term applied to xenobiotics other than drugs.

Term: Pharynx

Definition: Throat, the part of the digestive tract between the oesophagus below and the mouth and nasal cavities above and in front.

Source: NLM Toxicology Glossary

Term: Phenotype

Definition: This is a term which is applied to the appearance or constitutional nature of an organism as contrasted with its genetic potential, the genotype. See genotype.

Term: Photoemission electron microscopy (PEEM)

Definition: Method that involves imaging the distribution of electrons emitted from a surface when it is illuminated with linearly or circularly polarized x-rays.

Term: Photoluminescence spectroscopy

Definition: Spectroscopy of adsorbed and re-radiated photons.

Source: ISO/TS 80004-6:2013

Term: Photon correlation spectroscopy (PCS)

Method in which particles undergoing Brownian motion in a liquid suspension are illuminated by a laser and the change in intensity of the scattered light is used to determine particle size.

Source: ISO/TS 80004-6:2013

Term: Physical Vapour Deposition (PVD)

Process of depositing a coating by vaporising and subsequently condensing an element or compound, usually in a high vacuum.

Source: ISO/TS 80004-8:2013

Term: Physiology

Definition: Study of the biological, chemical and physical activities and processes that underlie the functioning of living organisms (cells, tissues, organs, and organ systems) and their parts.

Term: Placebo

Definition: An inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or treatment are compared to the effects of the placebo.

Source: NCI Dictionary of Cancer Terms

Term: Polymer matrix nanocomposite

Definition: Nanocomposite with at least one major polymeric phase.

Source: ISO/TS 80004-4:2011

Term: Precursor

Definition: A precursor is a chemical which precedes and is the source of another.

Source: GreenFacts

Term: Predicted Environmental Concentration (PEC)

Definition: The Predicted Environmental Concentration (PEC) is an indication of the expected concentration of a material in the environment, taking into account the amount initially present (or added to) the environment, its distribution, and the probable methods and rates of environmental degradation and removal, either forced or natural.

Term: Predicted no-effect concentration (PNEC)

Definition: The predicted no-effect concentration (PNEC) is the concentration below which exposure to a substance is not expected to cause adverse effects.

Term: Prevalence

Definition: Number of instances of existing cases of a given disease or other condition in a given population at a designated time; sometimes used to mean prevalence rate. When used without qualification, the term usually refers to the situation at a specified point in time (point prevalence).

Source: NLM Toxicology Glossary

Term: Protein

Definition: A large molecule composed of one or more chains of amino acids in a specific order, formed according to genetic information.

Source: GreenFacts Glossary

Term: Protein corona

Biomolecules (predominantly proteins) adsorbed onto the surface of a nano-object in a biological medium.

Source: ISO/TS 80004-5:2011

Term: Proteomics

Definition: The study of the structure and function of proteins, including the way they work and interact with each other inside cells.

Source: GreenFacts Glossary

Term: Pulmonary

Definition: Relating to, or associated with the lungs.

Source: GreenFacts Glossary

Term: Pulmonary alveoli

Definition: The pulmonary alveoli are minute air-filled sacs in the vertebrate lung, thin walled and surrounded by blood vessels.

Term: Quantitative structure-activity relationship (QSAR)

Definition: Quantitative analysis of the dependence of the biological effects of a chemical upon its molecular structure produces a structure activity relationship. Molecular structure and biological activity are correlated by observing the results of systematic structural modification on defined biological endpoints.

Term: Quantum dot

Definition: Crystalline nanoparticle that exhibits size-dependent properties due to quantum confinement effects on the electronic states.

Source: ISO/TS 27687:2008

Term: Raman spectroscopy

Definition: Spectroscopy in which the Raman effect is used to investigate molecular energy levels.

Source: ISO 18115‑2:2010

Term: Random sample

Definition: Subset of a population that is arrived at by selecting units such that each possible unit has a fixed and determinate probability of selection.

Source: NLM Toxicology Glossary


Definition: REACH is an acronym for Registration, Evaluation and Authorisation of Chemicals. This is a new system to regulate chemical use in the EU, which will replace a large quantity of existing legislation and place controls on some chemicals which are not currently covered by regulation. Reach came into law in June 2007. The effect of the legislation will be require companies to show that the chemicals they produce are safe for humans and for the environment.

Term: Reactive Oxygen Species (ROS)

Definition: Oxygen ions and molecules that are highly reactive due to the presence of unpaired electrons. They are formed during normal aerobic cellular metabolism and play an important role in redox signalling and in immune defences, but to prevent excessive cellular damage a balance is maintained by antioxidants that neutralise ROS.

Term: Receptor

Definition: High affinity binding site for a particular toxicant.

Source: NLM Toxicology Glossary

Term: Recommended limit

Definition: This regulatory value is the maximum concentration of a potentially toxic substance which is believed to be safe. Such limits often have no legal backing in which case a control or statutory guide level which should not be exceeded under any circumstances may be set. See control limit.

Term: Reduced graphene oxide

Definition: Graphene oxide that has been reductively processed by chemical, thermal, microwave, photo-chemical, photo-thermal or microbial/bacterial methods to reduce its oxygen content.

Source: Bianco et al. (2013)

Term: Relative risk

Definition: This term may have any of the following meanings depending upon context. (i) Ratio of the risk of disease or death among the exposed to the risk among the unexposed: this usage is synonymous with "risk ratio"; (ii) Alternately, the ratio of the cumulative incidence rate in the exposed to the cumulative incidence rate in the unexposed, i.e. the cumulative incidence ratio; (iii) Sometimes used as a synonym for "odds ratio". See risk.

Term: Renal

Definition: Pertaining to the kidneys.

Source: NLM Toxicology Glossary

Term: Reproductive toxicology

Definition: Study of the adverse effects of substances on the embryo, fetus, neonate and prepubertal mammal and the adult reproductive and neuro-endocrine systems.

Term: Reproductive toxicant

Definition: Substance or preparation that produces non-heritable harmful effects on the progeny and/or an impairment of male and female reproductive function or capacity.

Term: Respirable fibre

Definition: A particle with a diameter less than 3 µm and length greater than 5 µm and with a length to width ratio of greater than 3:1. These fibres can reach the deepest part of the lung.

Source: IARC Glossary

Term: Respirable fraction

Definition: Particle mass with a median aerodynamic diameter of 4 μm collected with 50% efficiency. Particles within the respirable fraction can be inhaled into the human respiratory system.

Term: Respiratory Irritant

Definition: Any substance which can cause inflammation or other adverse reactions in the respiratory system (lungs, nose, mouth, larynx and trachea). Examples of respiratory irritants include tobacco smoke, ozone, sulphur dioxide or nitrogen oxides.

Source: GreenFacts

Term: Respiratory tract

Definition: The organs that are involved in breathing. These include the nose, throat, larynx, trachea, bronchi, and lungs. Also known as the respiratory system.

Term: Risk

Definition: Risk is often considered to be the product of exposure and hazard. This term is most correctly applied to the predicted or actual frequency of occurrence of an adverse effect of a chemical or other hazard, and must not be confused with the term "hazard".

Term: Risk Assessment

Definition: Risk assessment is the identification and quantification of the risk resulting from a specific use or occurrence of a chemical, taking into account the possible harmful effects on individual people or society of using the chemical in the amount and manner proposed and all the possible routes of exposure. Quantification ideally requires the establishment of dose-effect and dose-response relationships in likely target individuals and populations.

Term: Risk management

Definition: Risk management is the decision-making process involving considerations of political, social, economic and engineering factors with relevant risk assessments relating to a potential hazard so as to develop, analyse and compare regulatory options and to select the optimal regulatory response for safety from that hazard. Essentially risk management is the combination of three steps: risk evaluation; emission and exposure control; risk monitoring.

Term: Risk phrases

Definition: Risk phrases, coded in the form R34, R61 etc are now included in MSDS sheets for chemicals purchased in the UK and in many other countries. A list of the meaning of these codes is available at

Term: Route of exposure

Definition: The way people [or other living organisms] come into contact with a hazardous substance. Three routes of exposure are breathing [inhalation], eating or drinking [ingestion], or contact with the skin [dermal contact].

Source: ATSDR

Term: Safety

Definition: Safety is the practical certainty that injury will not result from exposure to a hazard under defined conditions: in other words, the high probability that injury will not result. See practical certainty.

Term: Safety factor

Definition: See uncertainty factor.

Term: Scanning Electron Microscopy (SEM)

Definition: Method that examines and analyses the physical information (such as secondary electron, backscattered electron, absorbed electron and X-ray radiation) obtained by generating electron beams and scanning the surface of the sample in order to determine the structure, composition and topography of the sample.

Source: ISO 17751

Term: Scanning Force Microscope (SFM)

Definition: A SFM works by detecting the vertical position of a probe while horizontally scanning the probe or the sample relative to the other. The probe is in physical contact with the sample and its vertical position is detected by detecting the position of a reflected laser beam with a photo diode that consists of two or four segments.

Source: Institute of Nanotechnology Glossary

Term: Scanning ion microscopy

Definition: Method in which an ion beam focused into a sub-nanometre scale spot is scanned over a surface to create an image.

Source: ISO/TS 80004-6:2013

Term: Scanning mobility particle sizer (SMPS)

Definition: Real-time size-selective (mobility diameter) detection of number concentration. Data may be interpreted in terms of aerosol mass concentration, only if particle shape and density are known or assumed.

Source: BSI PD6699-3:2010

Term: Scanning Near Field Optical Microscopy (SNOM)

Definition: Method of imaging surfaces optically in transmission or reflection by mechanically scanning an optically active probe much smaller than the wavelength of light over the surface whilst monitoring the transmitted or reflected light or an associated signal in the near-field regime.

Source: ISO 18115‑2:2010

Term: Scanning probe microscopy (SPM)

Definition: Method of imaging surfaces by mechanically scanning a probe over the surface under study, in which the concomitant response of a detector is measured.

Source: ISO 18115‑2:2010

Term: Scanning Thermal Microscopy (SThM)

Definition: An atomic force microscopy (AFM) imaging mode that maps changes in thermal conductivity across a sample's surface. Similar to other modes that measure material properties, SThM data is acquired simultaneously with topographic data.

Source: NanoCharm Glossary

Term: Scanning Tunneling Microscope (STM)

Definition: A device that obtains images of the atoms on the surfaces of materials - important for understanding the topographical and electrical properties of materials and the behaviour of microelectronic devices. The STM is not an optical microscope; instead it works by detecting electrical forces with a probe that tapers down to a point only a single atom across. The probe in the STM sweeps across the surface of which an image is to be obtained. The electron shells, or clouds, surrounding the atoms on the surface produce irregularities that are detected by the probe and mapped by a computer into an image. Because of the quantum mechanical effect called 'tunnelling' electrons can hop between the tip and the surface. The resolution of the image is in the order of 1nm or less.

Source: Institute of Nanotechnology Glossary

Term: Scanning transmission electron microscopy (STEM)

Definition: Method that produces magnified images or diffraction patterns of the sample by a finely focused electron beam, scanned over the surface and which passes through the sample and interacts with it.

Source: ISO/TS 10797:2012

Term: Scanning tunneling microscopy (STM)

Definition: SPM mode for imaging conductive surfaces by mechanically scanning a sharp, voltage-biased, conducting probe tip over their surface, in which the data of the tunneling current and the tip-surface separation are used in generating the image.

Source: ISO 18115‑2:2010

Term: Scenario

Definition: A plausible and often simplified description of how the future may develop, based on a coherent and internally consistent set of assumptions about key driving forces (e.g., rate of technology change, prices) and relationships.

Source: GreenFacts

Term: Scientific Consensus

Definition: The Scientific Consensus represents the position generally agreed upon at a given time by most scientists specialised in a given field.

Source: GreenFacts Glossary

Term: Secondary-ion mass spectrometry

Definition: Method in which a mass spectrometer is used to measure the mass-to-charge quotient and abundance of secondary ions emitted from a sample as a result of bombardment by energetic ions.

Source: ISO 18115‑1

Term: Self-assembly

Definition: Autonomous action by which components organise themselves into patterns or structures.

Source: ISO/TS 80004-8:2013

Term: Sensitization

Definition: This is the term applied to the exposure to a substance (allergen) which provokes a response in the immune system such that disease symptoms will ensue on subsequent encounters with the same substance. See hypersensitivity, immune system.

Term: Short term exposure limit (STEL)

Definition: As used by US NIOSH, unless noted otherwise, the 15 minute time weighted average exposure that should not be exceeded at any time during a work day.

Term: Single-wall carbon nanotube (SWCNT)

Definition: Carbon nanotube consisting of a single cylindrical graphene layer.

Source: ISO/TS 80004-3:2010

Term: Skin cancer

Definition: A tumour that grows from skin cells and which can have different causes, including repeated severe sunburns or long-term exposure to the sun.

Source: GreenFacts

Term: Small angle neutron scattering (SANS)

Definition: Method in which a beam of neutrons is scattered from a sample and the scattered neutron intensity is measured for small angle deflection.

Source: ISO/TS 80004-6:2013

Term: Small angle X-ray scattering (SAXS)

Definition: Method in which the elastically scattered intensity of X-rays is measured for small-angle deflections.

Source: ISO 18115‑1

Term: Societal risk

Definition: Total probability of harm to a human population including also the probability of adverse health effects to descendants.

Source: NLM Toxicology Glossary

Term: Soluble

Definition: A substance is soluble if it dissolves in certain fluids. The fluid [gas or liquid] (present in excess) is called the solvent and the substance dissolved in it is called the solute which together form a solution. The process of dissolving is called solvation. A solution that can not hold any more solute is said to be saturated.

Source: GreenFacts

Term: Sorption

Definition: Noncommittal term used instead of adsorption or absorption when it is difficult to discriminate experimentally between these two processes.

Source: NLM Toxicology Glossary

Term: Speciation

Definition: Determination of the exact chemical form or compound in which an element occurs in a sample, for instance - determination of whether arsenic occurs in the form of trivalent or pentavalent ions or as part of an organic molecule, and the quantitative distribution of the different chemical forms that may coexist.

Source: NLM Toxicology Glossary

Term: Species

Definition: A group of organisms that differ from all other groups of organisms and that are capable of breeding and producing fertile offspring. This is the smallest unit of classification for plants and animals.

Source: OceanLink

Term: Species-specific sensitivity

Definition: Quantitative and qualitative features of response to the action(s) of a potentially toxic substance that are characteristic for particular species of living organism.

Term: Specific surface area mean diameter

Definition: Diameter calculated from a ratio of particle volume to specific surface area adsorption.

Source: ISO/TS 27687:2008

Term: Spray drying

Definition: Producing a dry powder from a liquid or slurry by rapid removal of liquid droplets via contact with a hot gas.

Source: ISO/TS 80004-8:2013

Term: Standard

Definition: 1. That which is established as a measure or model to which others of a similar nature should conform.

Term: Standard IARC Classification

Definition: Compounds or physical factors assessed by IARC (International Agency for Research on Cancer) are classified in four groups based on the existing scientific evidence for carcinogenicity.

Group 1: "Carcinogenic to humans" There is enough evidence to conclude that it can cause cancer in humans.
Group 2A: "Probably carcinogenic to humans" There is strong evidence that it can cause cancer in humans, but at present it is not conclusive.

Term: Standardisation

Definition: 1. Making any substance, drug or other preparation conform to type or precisely defined characteristics.

Term: Structure activity relationship (SAR)

Definition: The analysis of the dependence of the biological effects of a chemical upon its molecular structure produces a structure activity relationship. Molecular structure and biological activity are correlated by observing the results of systematic structural modification on defined biological endpoints.

Term: Sub-acute

Definition: Term used to describe a form of repeated exposure or administration usually occurring over about 21 days, not long enough to be called "long-term" or "chronic".

Term: Sub-chronic toxicity test

Definition: Animal experiment serving to study the effects produced by the test material when administered in repeated doses (or continually in food, drinking-water, air) over a period of up to about 90 days.

Source: NLM 

Term: Sub-chronic

Definition: Related to repeated dose exposure over a short period, usually about 10% of the life span; an imprecise term used to describe exposures of intermediate duration.

Term: Sub-chronic toxicity

Definition: 1. Adverse effects resulting from repeated dosage or exposure to a substance over a short period, usually about 10% of the life span.

Term: Surface enhanced Raman spectroscopy (SERS)

Definition: Enhanced Raman effect observed for certain molecules or nano-objects adsorbed to particular metal surfaces whose roughness is in the nanoscale when illuminated with suitable light.

Source: ISO/TS 80004-6:2013

Term: Surface functionalisation

Definition: Chemical process that acts upon a surface to impart a selected chemical or physical functionality.

Source: ISO/TS 80004-8:2013

Term: Susceptibility

Definition: Condition of lacking the power to resist a particular disease or infection; thus in susceptible people "normal expected" results occur but with a lower exposure (or dose) than in the rest of the population.

Source: NLM

Term: Suspension

Definition: Heterogeneous mixture of materials comprising a liquid and a finely dispersed solid material.

Source: ISO 4618:2006

Term: Synergistic effect

Definition: A synergistic effect is the any effect of two chemicals acting together which is greater than the simple sum of their effects when acting alone: such chemicals are said to show synergism.

Term: Synthesis

Definition: The production of a substance by either joining chemical elements, groups, and/or simpler compounds or breaking down a complex compound.

Term: Systemic

Definition: Relating to the body as a whole.

Term: Systemic effect

Definition: Consequence that is of either a generalised nature or that occurs at a site distant from the point of entry of a substance: a systemic effect requires absorption and distribution of the substance in the body.

Source: NLM

Term: Target cell

Definition: The biological cell(s) most adversely affected by exposure to a chemical substance.

Term: Target organ

Definition: The biological organ(s) most adversely affected by exposure to a chemical substance.

Term: Target organ dose

Definition: The target organ dose is the amount of a potentially toxic substance reaching the organ chiefly affected by that substance.

Term: Target tissue

Definition: The biological tissue(s) most adversely affected by exposure to a chemical substance.

Term: Tensile strength

Definition: The maximum amount of tensile stress that can be applied to it before it ceases to be elastic. If too much force is applied the material will break or become plastic, i.e., once the force exertion is stopped the material will not go back to its initial shape.

Source: Institute of Nanotechnology

Term: Teratogen

Definition: This is the descriptor applied to any substance that can cause non-heritable birth defects.

Term: Teratogenicity

Definition: Potential to cause or the production of structural malformations or defects in offspring.

Source: NLM

Term: Thin films

Definition: Thin films are atomically engineered layers of a wide variety of materials including metals, insulators and semiconductors. The major applications of thin films are in modification of the surface properties of solids. Individual films may be electrically conductive or non-conducting, hard or soft, thermally conducting or insulating, optically transparent, or opaque. A thin film coating can transform the electrical, mechanical and/or optical properties of a solid base material in a cost-effective way.

Term: Threshold

Definition: Dose or exposure concentration below which an effect is not expected.

Source: NLM

Term: Threshold limit value (TLV)

Definition: This is a guideline value defined by the American Conference of Governmental Hygienists to establish the airborne concentration of a potentially toxic substance to which it is believed that healthy working adults may be exposed safely through a 40 hour working week and a full working life. This concentration is measured as a time weighted average concentration (see below). They are developed only as guidelines to assist in the control of health hazards and are not developed for use as legal standards.

Term: Time weighted average concentration (TWA)

Definition: This is a regulatory value defining the concentration of a substance to which a person is exposed in ambient air, averaged over a period, usually 8 hours. For a person exposed to 0.1 mg m-3 for 6 hours and 0.2 mg m-3 for 2 hours, the 8 hour TWA is (0.1 x 6 + 0.2 x 2) / 8 which equals 0.125 mg m-3.

Term: Tissue

Definition: A group of cells joined to perform a set of functions.

Source: GreenFacts

Term: Tolerable Daily Intake (TDI)

Definition: TDIs are applied to chemical contaminants in food and drinking water. The presence of contaminants is unwanted and they have no useful function, differing from additives and residues where there is or was deliberate use resulting in their presence. TDIs are calculated on the basis of laboratory toxicity data with the application of uncertainty factors. A TDI is thus an estimate of the amount of a substance (contaminant) in food or drinking water that can be ingested daily over a lifetime without appreciable health risk.

Term: Top-down nanomanufacturing

Definition: Processes that create structures at the nanoscale from macroscopic objects.

Source: ISO/TS 80004-8:2013

Term: Toxic

Definition: This is the adjective applied to any substance able to cause injury to living organisms as a result of physicochemical interaction. See toxicity.

Term: Toxicant

Definition: This descriptor is applied to any substance which is potentially toxic. See toxicity.

Term: Toxicity

Definition: The term "toxicity" is used in two different senses. (i) Capacity to cause injury to a living organism; (ii) Any adverse effects of a chemical on a living organism. See Adverse effect. The severity of toxicity produced by any chemical is directly proportional to the exposure concentration and the exposure time. This relationship varies with the developmental stage of an organism and with its physiological status.
Acute toxicity
Adverse effects occurring within a short time of administration of a single dose of a chemical, or immediately following short or continuous exposure, or multiple doses over 24 hours or less.
Chronic toxicity
Adverse effects occurring as a result of repeated dosing with a chemical on a daily basis, or exposure to the chemical, for a large part of an organism's lifespan (usually more than 50%). With experimental animals, this usually means a period of exposure of more than 3 months. Chronic exposure studies over 2 years using rats or mice are used to assess the carcinogenic potential of chemicals. See carcinogenicity.

Term: Toxicity assessment

Definition: This is the process of defining the nature of injuries that may be caused to an organism by exposure to a given chemical and the exposure concentration and time dependence of the chemically induced injuries. The aim of the assessment is to establish safe exposure concentration limits in relation to possible time of exposure.

Term: Toxicodynamics

Definition: Process of interaction of potentially toxic substances with target sites, and the biochemical and physiological consequences leading to adverse effects.

Source: NLM

Term: Toxicokinetics

Definition: Process of the uptake of potentially toxic substances by the body, the biotransformation they undergo, the distribution of the substances and their metabolites in the tissues, and the elimination of the substances and their metabolites from the body. Both the amounts and the concentrations of the substances and their metabolites are studied. The term has essentially the same meaning as pharmacokinetics, but the latter term should be restricted to the study of pharmaceutical substances.

Source: NLM

Term: Toxicology

Definition: The study of the harmful effects of substances on humans or animals.

Source: ATSDR Glossary

Term: Toxin

Definition: A toxicant produced by a living organism.

Source: GreenFacts

Term: Transmission electron microscopy (TEM)

Definition: Method that produces magnified images or diffraction patterns of the sample by an electron beam which passes through the sample and interacts with it.

Source: ISO 29301:2010

Term: Tumour

Definition: An abnormal mass of tissue resulting from uncontrolled and excessive cell division. Tumours can be either benign (localised, without the invasion of other tissues) or malignant (showing progressive invasion of other tissues).

Source: GreenFacts

Term: Ultrafine particle

Definition: A particle with an equivalent diameter less than 100 nm.

Source: ISO 14644-6:2006 (Document withdrawn)

Term: Ultraviolet photoelectron spectroscopy (UPS)

Definition: Method in which an electron spectrometer is used to measure the energy distribution of photoelectrons emitted from a surface irradiated by ultraviolet photons.

Source: ISO 18115‑1

Term: Uncertainty factor

Definition: 1. In assay methodology, confidence interval or fiducial limit used to assess the probable precision of an estimate

Term: Uptake

Definition: Entry of a substance into the body, into an organ, into a tissue, into a cell, or into the body fluids by passage through a membrane or by other means.

Term: UV-Vis spectroscopy

Definition: Spectroscopy of radiation that consists of electromagnetic radiation with wavelengths in the ultraviolet and/or visible regions.

Source: ISO/TS 80004-6:2013

Term: Validity

Definition: Of a measurement: Expression of the degree to which a measurement measures what it purports to measure.

Term: Volatile

Definition: Able to readily evaporate at normal temperatures and pressures.

Term: Volume specific surface area

Definition: Absolute surface area of the sample divided by sample volume.

Source: ISO 9277:2010

Term: Weight-of-evidence for toxicity

Definition: Extent to which the available biomedical data support the hypothesis that a substance causes a defined toxic effect.

Term: Wet ball milling

Definition: Grinding process in liquid via rolling feedstock material with crushing balls of greater hardness to create a force of impact in order to reduce the size of target components.

Source: ISO/TS 80004-8:2013

Term: Xenobiotic

Definition: A chemical which is not a natural component of the organism exposed to it.

Term: X-ray absorption spectroscopy (XAS)

Definition: Method in which the absorption of X-rays passing through matter is measured as a function of X-ray energy.

Source: ISO/TS 80004-6:2013

Term: X-ray auger electron spectroscopy (XAES)

Definition: Method in which an electron spectrometer is used to measure the energy distribution of Auger electrons emitted from a surface after irradiation with x-rays.

Source: NanoCharm

Term: X-ray diffraction

Definition: Method to obtain crystallographic information about a sample by observing the diffraction pattern due to an X-ray beam hitting a sample.

Source: ISO/TS 80004-6:2013

Term: X-ray fluorescence (XRF)

Definition: Secondary radiation occurring when a high intensity incident X-ray beam impinges upon a material placed in the path of the incident beam.

Source: ISO 3497:2000

Term: X-ray photoelectron spectroscopy (XPS)

Definition: Method in which an electron spectrometer is used to measure the energy distribution of photoelectrons and Auger electrons emitted from a surface irradiated by X-ray photons.

Source: ISO 18115‑1

Term: Zeta potential

Definition: Difference in electric potential between that at the slipping plane and that of the bulk liquid.

Source: ISO 13099‑1:2012