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Toxic Driveways: Cancer Risk from PAH in Coal Tar SealantJun. 11, 2015 By James Bilsborrow
Thinking of resealing your driveway this summer? You might want to think twice before using a driveway sealcoat made with coal tar. Otherwise, your driveway may end up making you and your family sick.
Every year, millions of homeowners apply a new sealcoat to cracked and deteriorating driveways. The most common of these pavement sealant products are made with coal tar.
Coal tar is a byproduct of the coke used in steel manufacturing processes. The tar is refined and sold to sealant manufacturers, who then mix in various additives to create a marketable pavement sealing product that can be sprayed or painted on driveways and parking lots. Because the sealcoats break down over time, a new coat is typically applied every two to three years to preserve the appearance of the surface.
An estimated 85 million gallons of coal tar sealcoat is sold in the United States every year. What most homeowners do not know, however, is that sealants made from coal tar are highly toxic and harmful to human (and animal) health.
Driveway Sealer Breaks Down; Toxic Dust Gets Into Homes
Coal tar sealants contain unacceptably high levels of polycyclic aromatic hydrocarbons (PAHs), a class of toxic and carcinogenic chemicals that are considered priority pollutants by the Environmental Protection Agency.
As the sealants break down over time, they become fine particle dust. Some of that dust blows into the air, some runs off onto neighboring lawns, and some is carried into nearby homes via foot traffic. The dust carried into the home then settles in the carpet or on the floor where it is often ingested by small children or animals.
Over time, the coal tar dust buildup is significant. Researchers from the United States Geological Survey observed that apartment buildings adjacent to a coal tar sealed parking lot contained PAH concentrations 25 times greater than the concentrations found in buildings next to an unsealed lot or a lot treated with a non-coal tar sealcoat. The concentration of PAHs in the dust from the coal tar sealed lots was 530 times higher, on average, than the concentration measured on lots without coal tar sealcoats.
PAH in Coal Tar Sealants Increases Cancer Risk
What does this mean for your family’s health? PAH exposure has been linked to increased risk for:
- Lung cancer
- Skin cancer
- Bladder cancer
- Respiratory and urinary tract cancers
Studies increasingly show that smaller children and animals face the greatest exposure risks. Indeed, the presence of coal tar dust is especially concerning for young children, who often spend a significant amount of time crawling on the floor and placing hands and other objects into their mouths.
Children in homes adjacent to coal tar sealed lots are exposed to doses of PAHs that are on average 14 times higher than the exposures experienced by children living adjacent to unsealed lots or lots sealed with a non-coal tar sealcoat.
These exposures, in turn, account for the vast majority of an individual’s lifetime dosage. A child’s maximum dosage occurs at the youngest ages, when body weight is low and the ingestion rate is high. Approximately 50 percent of the lifetime dosage occurs within the first six years of life, and 80 percent of the lifetime dosage occurs by the age of 18.
Therefore, young children living near a coal tar sealed driveway or lot are likely to experience a significant dosage at an early age. Researchers have concluded that children are 38 times more likely to develop cancer when they are raised in the presence of house dust affected by coal tar. It is thus critical to prevent very young children from elevated PAH exposures.
Safer, Less Toxic Pavement Sealcoats Exist
Given this data, why would anyone seal their driveway with a coal tar based sealcoat? Unfortunately, most people are unaware of the dangers posed by coal tar sealants, and many do not know that safer, less toxic alternatives exist.
Asphalt-based sealcoats, for example, cost about the same as coal tar sealcoats, yet contain 1,000 times fewer PAHs. On this basis alone, the choice should be a no-brainer. But many homeowners simply apply a coal tar based sealcoat without warning or knowledge of the risks.
Communities around the country, however, are catching on to the dangers of coal tar. In 2005, Austin, Texas banned the use of coal tar sealcoats. Over the next eight years, the presence of PAH concentrations in Austin’s lakes dropped a precipitous 58 percent.
Austin’s example was followed by statewide bans in Washington and Minnesota, a citywide ban in the District of Columbia, and county bans in Dane, Wisconsin; Prince George’s County, Maryland; and Suffolk, New York, just to name a few. All told, some 17.5 million people live in communities operating under a coal tar ban.
These communities are moving in the right direction. As the science linking PAH exposures and cancer risks continues to become more irrefutable, a greater number of communities will enact bans of their own.
But what can you do if your driveway or a nearby lot is sealed with coal tar sealant? How can you protect your young children, who are at greater risk from PAH exposure?
Weitz & Luxenberg’s environmental pollution unit has been working with scientists who specialize in the dangers of exposure to coal tar sealant and we have been following developments about its risks. If you are worried about the damage coal tar sealant can do to your family’s health, reach out to us. We may be able to assist you in testing your home and property for the presence of dangerous PAHs linked to coal tar pavement sealant.