Driveway sealers may be cancer time bombs
By Frank Abderholden firstname.lastname@example.org April 3, 2012 7:38PM
Updated: June 3, 2012 1:28AM
LIBERTYVILLE — The controversy over whether or not coal tar in driveway sealants are dangerous to your health and the environment came to Lake County on Tuesday at an informational meeting led by a McHenry County water resources manager.
Cassandra McKinney shared information on legislative initiatives in Illinois and across the nation to ban coal tar sealants used to give driveways and parking lots a fresh new sheen and lengthen the life span of the asphalt. Approximately 85 million gallons are used each year in the U.S..
McKinney said polycyclic aromatic hydrocarbons (PAHs) are formed by the incomplete combustion of organic materials. They are used in sealants for their binding properties, according to a sealant company owner who did not want his name used. He complains other sealants don’t last.
There are actually thousands of different kinds of PAHs and the U.S. Environmental Protection Agency lists 16 as priority pollutants, chemical pollutants EPA regulates. Opponents of PAH bans point out human exposure to PAHs also comes from car exhaust, grilled meats and vegetables, wood fires, prairie burns, tobacco and other sources of combustion.
McKinney said that recent studies of the effect of coal tar sealant flakes on frogs in a lab showed that they took longer to hatch and were developmentally smaller. The study showed that at higher levels of the tar, the frogs died. Another study found high PAH in sediments were linked to mouth tumors in fish.
McKinney cited research that said in the past scientists assumed PAH exposure in children was due mainly to food. But a Baylor University study found children in an apartment complex next to parking lots treated with coal tar sealants were likely to receive twice as much PAHs from incidental ingestion of house dust than their diet. Those children ingested 14 times as much as children living next to unsealed lots.
While car exhaust is a big producer of PAHs, the U.S. Geological Survey recently stated in a scientific journals Chemosphere and Atmospheric Environment that coal tar sealants were emitting PAHs at rates that may be greater than the annual emissions from vehicles in the US.
The Agency for Toxic Substances and Disease Registry (ATSDR), a federal public health agency of the U.S. Department of Health and Human Services, says that PAHs are reasonably anticipated to be cancer causing to humans. It also noted they are used in medicines, dyes, plastics and pesticides.
It said while animal studies showed it harmed the immune and reproductive systems of mice, but the effects have not been seen in people. “PAHs can be harmful to your health under some circumstances,” reads the public health statement on the compound. Exposure through breathing or skin contact for long periods to mixtures containing PAHs and other compounds could cause cancer to develop.
Anne LeHuray, executive director of the Pavement Coatings Technology Council, argues the seal coat industry is not the primary source of PAHs and shouldn’t be made a scapegoat for PAHs in the environment. “No one is surprised that refined tar-based sealant contains PAHs. PAHs are everywhere in the environment,” she said.
So where does that leave the consumer and government officials? Both Home Depot and Lowes stopped selling coal tar-based driveway sealant. Asphalt sealant still has coal tar, “but a significantly lower percentage,” said McKinney — 50 milligrams per kilogram compared to 50,000 for coal tar sealants.
Federal legislation that would ban it is in committee and in Illinois there is a House bill in committee that is exploring changing the rules so that non-home rule communities could ban it.
McHenry County restricts its use and Lake County is looking at the issue, according to Michael Adams, senior biologist for the Health Department and Community Health Center.