Coal-based Pavement Sealant Is Leading Source of Toxin in U.S. Lakes

A coal-based sealant sprayed on pavement for parking lots, playgrounds, and driveways is the leading contributor of a toxic pollutant found in U.S. lakes and reservoirs, according to a new study. Samples of sediments collected from the bottom of lakes and reservoirs in 40 urban areas by the U.S. Geological Survey revealed high levels of polycyclic aromatic hydrocarbons (PAHs), a probable carcinogen that is also toxic to fish and other marine life. On average, about half of the PAHs came from coal-tar sealants. Vehicles account for about one-fourth of the remaining pollutants, and coal combustion contributes about 20 percent, according to the study, published in the journal Science of the Total Environment. Coal-tar pavement sealants — derived from the waste produced in the coking of steel — have been banned in several U.S. cities, including Austin, Texas, and Washington, D.C. An alternate asphalt-based sealant contains levels of PAHs that are 1,000 times lower than coal-tar sealants