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Diesel inhalation stresses your brain
11/03/2008
If the smell of diesel exhaust isn't enough to make you avoid getting a lungful, new research now shows that even a short exposure to the fumes can affect your brain. A study published in the open access journal Particle and Fibre Toxicology reveals that an hour of sniffing exhaust induces a stress response in the brain's activity.
Previous studies have already suggested that ultrafine particles breathed in from polluted air can end up in the brain. But this is the first time that scientists have demonstrated that inhalation actually alters brain activity.
Ten volunteers spent one hour in a room filled with either clean air or exhaust from a car diesel engine. They were wired up to an electroencephalograph (EEG), a machine that records the electrical signals of the brain, and their brain waves were monitored during the exposure period and for one hour after they left the room. The researchers found that after about 30 minutes the diesel exhaust began to affect brain activity. The EEG data suggested that the brain displayed a stress response which continued to increase even after the subjects had left the exposure chamber. The concentration of diesel exhaust was set to the highest level that people might encounter in the environment or at work, for example on a busy road or in a garage.
Lead researcher Paul Borm from the Centre of Expertise Life Sciences at Zuyd University in The Netherlands said: "We believe our findings are due to an effect of nanoparticles that slowly penetrate the brain or affect neurophysiologic signaling. We can only speculate what these effects may mean for the chronic exposure to particulate matter and/or nanoparticles we get from the environment." Oxidative stress has been implicated in degenerative brain diseases such as Parkinson’s and Alzheimer’s disease. "It is conceivable that the long-term effects of exposure to particulate matter might include a decrease in cognitive function," noted Borm. "Further studies are necessary to establish whether nanoparticles may induce this effect, and to explore the relationship between the brain's response and the dose of particles, and investigate the clinical implications of the novel findings from this research."
BBC news have today featured publication of this paper, and included the following from Prof Ken Donaldson, Editor of Particle and Fibre Toxicology, and founding member of SnIRC.
The fact that the brain responds when confronted with a new smell is not entirely surprising, says Ken Donaldson.
"It may not necessarily be negative, but such physiological changes do warrant investigation because there could indeed be a long-term effect. It's a very interesting, and potentially important, study."
Controlled studies examining the impact of pollution on the brain are ethically problematic, while longer-term studies of the population in polluted areas can be practically difficult as brain diseases are not necessarily noted on the death certificate as the cause of death.
Alzheimer's patients for instance often die of infection.
But a study of dogs in Mexico found those who lived in highly-polluted Mexico City had brain lesions similar to those seen in Alzheimer's patients, while those who lived in much less-polluted rural areas showed a much lower rate of damage to the brain.
The full article will be available from Particle and Fibre Toxicology online on publication:
Exposure to diesel exhaust induces changes in EEG in human volunteers. Bjoern Cruts, Ludo van Etten, Hakan Tornqvist, Anders Blomberg, Thomas Sandstrom, Nicholas L Mills and Paul JA Borm. Particle and Fibre Toxicology (in press)
Source: Centre of Experise Life Sciences, BBC
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