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Editor's Correspondence
July 9, 2012

Polycyclic Aromatic Hydrocarbons, Particulate Air Pollution, and Cognitive Decline

Author Affiliations

Author Affiliation: Sunlight, Nutrition, and Health Research Center, San Francisco, California.

Arch Intern Med. 2012;172(13):1045-1046. doi:10.1001/archinternmed.2012.1698

The recent article by Weuve and colleagues1 provides additional evidence that particulate air pollution contributes to cognitive decline. The mechanisms suggested to explain the observed association are generally consistent with an additional characteristic of a major component of PM2.5 (particulate matter ≤2.5 μm in aerodynamic diameter), black carbon, namely adsorption of polycyclic aromatic hydrocarbons (PAHs). The role of PAHs in cancer and reproductive and cardiovascular disease was reviewed by Lewtas.2 One PAH, benzo[a]pyrene, has been shown to cause neuronal death in a mouse through a combination of increase in reactive oxygen species, nitric oxide, and proinflammatory cytokines.3 Smoking is a risk factor for cognitive decline,4 and both particulates and PAHs are important emissions from smoking tobacco.

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