Numerous states and municipalities are banning the use of coal tar sealants commonly used in the paving of driveways, parking lots, and roadways. Research indicates that coal tar sealants are a major source of polycyclic aromatic hydrocarbons, or PAHs. At high levels of exposure, these chemicals are known to be toxic. In 2015, the U.S. Geological Survey (USGS) did two studies that determined that runoff from pavement seal-coated with coal tar was toxic to aquatic life, had detrimental effects on DNA, and “are probable human carcinogens.”
An estimated 85 million gallons of the black, shiny, coaltar-based sealant are applied to pavement each year, primarily east of the Continental Divide in the U.S. and parts of Canada, according to the USGS.
Anne LeHuray, of the Pavement Coatings Technology Council, claimed that coal-tar-based products last longer, protect better, and are proven products. Coal tar can also be applied in cold weather. The most common alternative to coal-tar-based sealants is an asphalt-based sealant, which LeHuray said does not protect as well as coal tar.