Washington Bans Coal Tar Sealants for Asphalt

By Paula MeltonResponding to research on toxic runoff caused by coal tar pavement sealants, the State of Washington has banned their use. Coal tar sealant is sprayed or painted onto asphalt playgrounds, parking lots, and driveways to help prevent water penetration and resulting frost heaves. The sealant is common in the Midwest, because the substance is produced when coal is turned into coke for use in steel; coal tar contains polycyclic aromatic hydrocarbons (PAHs), a known human carcinogen. Although industry sources claim that the PAHs do not leach out after application, U.S. Geological Survey studies have found that the sealant is the single largest source of PAH pollution in many urban lakes, and that dust on driveways with coal tar sealants can contain highly concentrated levels of toxic chemicals. While many local governments already outlaw or restrict coal tar sealants, this is the first statewide ban. Asphalt-based sealants, a more expensive alternative to coal tar, are considered less toxic.