A recent study in the journal Environmental Science and Technology found that coal tar-based asphalt sealants commonly used to update residential driveways and commercial parking lots contains an ingredient that may cause cancer, especially in children. According to the study, the black sealcoat is essentially a chemical compound called polycyclic aromatic hydrocarbon, or PAH, in concentrated form. PAH is known to cause cancer.
Asphalt sealant is only one of many consumer products that contains PAH or other cancer-causing agents. Plastics, rubber and lubricants all can contain PAHs, and other consumer products are known to contain carcinogens. These asphalt sealants, however, are popular enough that around 85 million gallons are applied every year to pavements in the U.S. and Canada. Unfortunately, the very pressure of vehicles on pavement treated with these sealants creates an airborne dust that gets transferred to nearby soil and tracked into people’s homes.
“When tires drive across it, it’s the grinding action of the tires that breaks up the little particles and grinds it up to a dust, essentially,” said the study’s lead author, a research hydrologist with the U.S. Geological Survey.
To find out how much of a problem that might be, researchers swept dust from ground-level apartments and condos in Chicago and New Hampshire. Half of the communities had asphalt parking lots treated with the sealants, and half did not. They also collected nearby soil samples. They then measured the levels of PAHs from the dust and soil and compared the results with the levels considered by the EPA to create an “excess cancer risk.”
In the homes near parking lots treated with the asphalt sealant, the cancer risk was 38 times higher than the EPA’s “excess cancer risk” level.
This is especially troubling for families with children. According to the researchers, by the age of six, children have accrued as much as 50 percent of the PAH exposure that leads to excess cancer risk. By the age of 18, they have 80 percent of the cancer-causing level in their systems.
“What does it mean for me? Maybe I should try to avoid that risk. And especially avoid the risk in my children,” an American Cancer Society biostatistician commented to HealthDay News.
Source: NewsInferno, “Asphalt Sealant May Increase Cancer Risks,” Cynthia A. Diaz-Shephard, April 5, 2013