"Airborne emissions and stray dust from coal tar–based sealers, one of the two main types of products used to coat certain asphalt pavements, may be a more significant human health threat than previously thought, according to three new studies and a review published by U.S. government and university researchers."
"The findings build on previous research on coal tar–based sealers (mostly on environmental impacts via runoff and other pathways) and provide novel insights on pathways of human exposure and the magnitude and duration of the emissions. But 'we’re just at the very beginning as far as [understanding] human health effects,' says Peter Van Metre, coauthor of all four publications and a research hydrologist with the U.S. Geological Survey.
Asphalt is used extensively to pave parking lots, driveways, airport runways, roads, playgrounds, paths, and other surfaces. Sealers are marketed as products that can help prevent pavement degradation and improve appearance, and they are used across the United States on all types of asphalt surfaces, with the exception of roads. The two most popular sealer types are emulsions based on either refined coal tar or asphalt ingredients.
Coal tar–based sealers contain an average concentration of 16 polycyclic aromatic hydrocarbons (PAHs) about 1,300 times greater than that found in asphalt-based sealers, and in 2003 coal tar–based sealers became a suspect contributor to the elevated concentrations of PAHs in metropolitan areas. PAHs are known or suspected to cause cancer, reproductive problems, birth defects, genetic mutations, and damage to the liver, blood, skin, and immune system, although data for both people and animals are limited. The primary source of PAHs is thought to be incomplete combustion of organic substances by sources such as power plants, vehicles, wildfires, food grilling, and cigarettes, although they also occur in a variety of consumer products."
Bob Weinhold reports for Environmental Health Perspectives May 1, 2012.
