Living near asphalt that has been sealed with coal tar could raise the risk of developing cancer, according to a new study. Young children appear to be those who are at the greatest risk. Coal tar, which is a by-product of steel manufacturing, is a common ingredient in the sealants that are used in the Eastern part of the United States to relay car parks and driveways.
The problem comes from the shiny black sealcoats are a concentrated source of cancer-causing chemicals called polycyclic aromatic hydrocarbons (PAHs). When tires drive across it, the grinding action of the tires breaks up tiny particles and turns it into a dangerous dust. That dust then gets carried into homes on shoes and hands. It’s also washed into the surrounding soil and waterways after a rain.
Previous studies have found high levels of these chemicals in dust vacuumed from homes that sit near sealcoat-covered asphalt. For the new study, which was published in the journal Environmental Science & Technology, the team of researchers compared the levels of PAHs in house dust swept from 23 apartments in Austin.
The researchers combined the levels with measurements of PAHs in soils sampled near car parks with and without coal tar-based sealants in New Hampshire and Chicago. They then plugged those numbers into models used by the U.S Environmental Protection Agency to ascertain what is called excess cancer risk.
Based on these models, for every million people who live near unsealed asphalt for 70 years there would be three extra cases of cancer due to the exposure to the PAHs. The study found that the risk is 38 times greater for people living near asphalt sealed with coal tar.