National Water-Quality Assessment (NAWQA) Program
Coal-tar-based pavement sealant is the largest source of polycyclic aromatic hydrocarbons (PAHs) to 40 urban lakes studied by the U.S. Geological Survey. On average, coal-tar-based sealcoat accounted for one-half of PAHs in the lakes, while vehicle-related sources accounted for about one-quarter. Elevated concentrations are generally associated with those lakes with a large contribution of PAHs from sealcoat, in many cases at levels that can be harmful aquatic life. Historical trends for a subset of studied lakes indicate that sealcoat use has been the primary cause of increases in PAHs since the 1960s.The study, published in the journal Science of the Total Environment, along with other USGS findings on PAHs are accessible at http://tx.usgs.gov/sealcoat.html.