Coal tar asphalt sealants may be bad actors

Research recently published by the United States Geological Survey points to coal tar asphalt sealants as a major source of human carcinogens in the environment, potentially greater than annual polycyclic aromatic hydrocarbons  emissions from vehicles.

The researchers state that children living in apartments adjacent to parking lots with coal-tar-based sealcoat likely receive more than twice as much polycyclic aromatic hydrocarbons from incidental ingestion of house dust than from their diet, previously thought to be a significant pathway for exposure to PAHs. PAH ingestion by children in those settings was estimated to be 14 times higher than by children in apartments adjacent to unsealed parking lots. The coated pavement areas continue to release PAHs for years after the coating was applied. Other exposure routes may include via applicators of coal-tar sealants and through those that work in close proximity to coated parking areas and bring surface dust into buildings and homes via their clothing. The research also documents transfer of PAHs from coated pavement areas through runoff into surface waters.

PAHs are designated as a toxic substance under the Canadian Environmental Protection Act.

In a typical industry association response the Executive Director of the US Pavement Coatings Technology Council is quoted in the media as stating “It appears they have some other agenda here, which is to ban coal tar-based pavement sealants.”

Companies that use coal tar based sealants to maintain parking lots and roadways are advised that public criticism of their release of human carcinogens into the environment may be imminent. Government regulation of coal tar based asphalt sealants is likely several years away.

For details of the studies visit

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