A study of coarse and fine particulate matter (PM) generated by the California wildfires of 2008 suggests a toxicity level greater than that of an equivalent dose of PM in ambient air, as reported in the January 2009 issue of the peer-reviewed journal Environmental Health Perspectives (EHP). The study adds to growing literature supporting source and component specific differences in toxicity of pollutant particles of a given size, and challenges regulators to consider toxicity as well as mass or size when regulating particle pollution.
Toxicity of coarse and fine PM obtained during peak smoke during the wildfires was determined with a mouse bioassay and compared with PM samples collected under normal conditions from the region during the same time the previous year.
“These observations highlight the critical importance of bioassays of toxicity of inhaled pollutants in whole animals as a component of a balanced scientific approach to estimating their toxicity,” wrote the research team, which included first author Teresa Wegesser, Kent E. Pinkerton, and Jerold A. Last.
“These findings add to the accumulating evidence that all particles of a given size class do not necessarily have the same toxicity, and suggest that the current standard for particulate matter may need reconsideration,” said EHP editor-in-chief Hugh A. Tilson, PhD. “The challenge is to integrate this accumulating evidence regarding particle toxicity in a way that is applicable to regulation and review of the Clean Air Act.”
The article is available free of charge at: http://www.ehponline.org/docs/2009/0800166/abstract.html.