A popular pavement sealcoat used in driveways and parking lots across the nation may pose a public health and environmental risk, according to new research by University of New Hampshire scientists.
The study, published in the journal Environmental Science & Technology, has found the black-surface asphalt application marketed as Sealcoat has high concentrations of organic compounds known as polycyclic aromatic hydrocarbons (PAHs), linked to cancer and other health problems.
Researchers said university experiments found PAH levels are about 1,000 times higher in coal-tar-based produces like Sealcoat than those based in asphalt.
According to the Department of Health and Human Services, PAHs are a group of over 100 different chemicals formed during the incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat. Animal studies have found PAHs may pose reproductive health problems, birth defects and immune-system problems. Health officials have also determined “some PAHs may reasonably be expected to be carcinogens,” according to information posted on the DHHS website.
For the new study, New Hampshire researchers led by Alison Watts and colleagues compared PAH levels in coal-tar-based sealcoated and nonsealcoated parking lots at university parking lots. They found soil at the edge of the sealcoated lot contained significantly higher levels of PAHs.
Their recommendation: Avoid coal-tar-based sealcoats in favor of asphalt-based ones, or no sealcoat at all.
"Consumers generally can't tell the difference," Watts said, noting retailers Home Depot and Lowes no longer sell coal-tar-based sealcoat, and several commercial sealcoaters use only asphalt-based sealcoat. "The crux of this issue is that it's a fairly simply choice we can make that will be beneficial to the environment and to human health without significant impact to the users."