Study: parking lot dust may raise cancer risk

Sealant wears off

Steve Hawley, Jan 15, 10.

A new study in Environmental Science and Technology reveals that carcinogenic chemicals used to seal parking lots and driveways are showing up in high levels in homes, according to MSNBC.

The article reports:

The substance is coal tar sealant, a waste product of steel manufacturing that is used to protect pavement and asphalt against cracking and water damage, and to impart a nice dark sheen. It is applied most heavily east of the Rockies but is used in all 50 states.

But scientists with the U.S. Geological Survey say the sealant — one of two types commonly used in the U.S. — doesn’t stay put. It slowly wears off and is tracked into homes on the shoes of residents.

The scientists are concerned that the chemicals could impact human health, particularly in children. Coal tar is a known carcinogen, and some of its components may cause health issues for babies exposed to the chemicals in the womb.

The research was conducted on 23 ground-floor apartments in Austin - 11 of which had coal tar-sealed parking lots and 12 of which had parking lots coated with other substances or not sealed at all. On average, levels of the harmful chemicals were 25 times higher in the apartments next to parking lots sealed with coal tar. According to the researchers, an extra one child in 10,000 would develop cancer if exposed to those levels over the course of a lifetime.

The researchers suggest using other substances to seal pavement, and US Rep. Lloyd Doggett, who represents Austin, has called for a nationwide ban of coal tar sealants. According to the article, “some 59 million gallons — enough to fill nearly 90 Olympic-sized swimming pools — are applied in Texas each year.” Researchers are also concerned about the effects the chemicals could have once they enter the water supply.

Full paper: Coal-Tar-Based Parking Lot Sealcoat: An Unrecognized Source of PAH to Settled House Dust (pdf, 381 kb) (also available in html)

(Photo credit: Elf)