Proximity To Parking Lots And Sealed Pavements Linked With Elevated Cancer Risk

Ongoing research regarding the health effects of coal tar sealant frequently used on pavements and parking lots has indicated an elevated risk of cancer in people who live near asphalt pavement sealed with coal tar.

"The increased cancer risk associated with coal-tar-sealed asphalt likely affects a large number of people in the U.S."  said Dr. E. Spencer Williams, principal author of the study at Baylor University. "Our results indicate that the presence of coal-tar-based pavement sealants is associated with significant increases in estimated excess lifetime cancer risk for nearby residents," 

The study calculated risks from children's exposure polycyclic aromatic hydrocarbons (PAHs) that are found in the coal tar sealant.

Coal tar sealant, or sealcoat, is a shiny black substance sprayed or painted onto asphalt pavement to improve appearance and protect the underlying asphalt from damage.

In the U.S., an estimated 85 million gallons of sealcoat are used on pavements each year.

Baylor University stated that the research was the first of its kind to report on potential human health effects from PAHs, which can be tracked into homes on the bottoms of shoes, settle in household dust and seep into soil adjacent to lots where the coal tar sealant is used.

"Exposure to these compounds in settled house dust is a particularly important source of risk for children younger than six years of age, as they are expected to ingest this material at higher rates," Williams said. "This indicates that the use of coal-tar-based pavement sealants magnifies aggregate exposures to PAHs in children and adults in residences adjacent to where these products are used and is associated with human health risks in excess of widely accepted standards."

Researchers first raised alarm about the potential health risks from the sealant in 2010, when the U.S. Geological Survey voiced concerns after high levels of chemicals used in the sealant were found in household dust, prompting experts to question whether it was advisable to use the coal tar sealant.

"This is the kind of thing where, when you give a presentation, people's eyes get big - even scientists," said Barbara Mahler, a USGS hydrologist who directed the 2010 research, according to NBC News.

Coal tar has been known to cause cancer in humans since the 1700s, when chimney sweeps in London were found to have high rates of scrotal cancer.

NBC also reported that babies exposed to PAHs while in the womb may be more prone to asthma and other ailments and may have lower IQs.