John Balbus, M.D., M.P.H., is Chief Health Scientist.
It’s been a worry for engineered nanoparticles. Now, a new study from the Harvard School of Public Health (Suglia et al., 2008) is the first to suggest that particulate air pollution not only damages the lungs and heart, but also may damage the developing brain.
Researchers measured cognitive function in over 200 children in Boston in relation to their residential exposure to traffic-related air pollution by measuring airborne carbon black particles. They found the IQ-lowering effect of higher exposure is comparable to a pregnant mother smoking 10 cigarettes a day or moderate lead exposure.
It’s important to note that carbon black is only used as an indicator for traffic-related particle pollution in this study, and the authors stress that it should not be concluded that pure carbon black is the causative agent here. The actual particles inhaled are likely to be contaminated by heavy metals and other toxins, and these may well be the culprits or at least greatly contribute to the actual damage to brain tissues. But it does suggest that some of the ultrafine fraction of air pollution finds its way into the brain and causes harm.
This study may not be making headlines in the nanoworld, but the nanoworld should be taking notice.
The authors hypothesize that the combustion particles make their way via the olfactory nerves from the children’s nasal passages directly into the children’s brains, as has been demonstrated for a variety of engineered nanoparticles in animal models (e.g., Oberdorster et al., 2004; Elder et al., 2006). Once there, the particles, including attached contaminants, may cause oxidative stress, ultimately leading to inflammation and cellular malfunction and/or damage. The study did control for potentially confounding factors like maternal cigarette smoking, lead levels in the children’s blood, mother’s educational level, low birth weight, and other factors.
This study should give pause to those who are making nanoparticles containing known neurotoxins, such as lead and manganese. And with growing understanding of the linkages between developmental and degenerative diseases of the brain, there’s reason to think that processes that lead to IQ loss in growing kids can impair brain functioning in aging adults. One more reason to avoid inhalation of nanoparticles, especially those with known capacity to cause oxidative stress.