Sealants Are Source Of Lake Pollution

Coal-tar-based pavement sealants are the largest source of polyaromatic hydrocarbon (PAH) pollution in many urban lakes, according to newly published research by U.S. Geological Survey scientists. The National Toxicology Program classifies eight PAHs found in coal tar as “reasonably anticipated to be human carcinogens.” They are also toxic to aquatic organisms. In the study, published in Science of the Total Environment, USGS scientists analyzed sediment cores from 40 U.S. lakes, then determined the sources of PAHs (DOI: 10.1016/j.scitot env.2010.08.014). Coal-tar-based sealants contributed about half of PAHs in the lakes on average, the researchers found. Another quarter came from spilled motor oil and particles worn from tires. In addition, the study reported that levels of PAHs were significantly higher in lakes of the eastern and central U.S., where coal-tar-based sealants predominate the market.