A water pollution episode in Austin, Texas, is raising questions about the environmental impact of coal tar-based sealants used on thousands of parking lots throughout the United States, according to an article scheduled for the Feb. 12 issue of Chemical & Engineering News (C&EN), the American Chemical Society's weekly newsmagazine.
In the article, C&EN senior editor Cheryl Hogue explains that the episode involved polycyclic aromatic hydrocarbon (PAH) pollution found near a popular Austin swimming spot. Consisting of more than 100 compounds, including several suspected human carcinogens, PAHs originate in numerous sources including the coal tar used in asphalt sealants — mainly those sold to commercial applicators.
After scientists linked the Austin PAH pollution to runoff from coal tar-based sealant applied to an apartment building parking lot, the city of Austin banned sale of these coatings. Municipalities in Wisconsin and Florida are considering a similar ban, and two major retailers, The Home Depot and Lowe's, have discontinued sale of coal tar-based sealants, the article states.
Manufacturers of coal tar-based sealcoats dispute the link, maintaining that Austin officials were premature in instituting the ban following publication of research in 2005 in the ACS journal, Environmental Science & Technology about the source of the Austin pollution. Manufacturers claim that most PAHs in Austin waterways originate from the city's highways, which collect PAHs from motor vehicle exhaust, tire wear and oil drips, the article adds.
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