Coal-Tar Sealants

It won't be long now before spring is in the air, along with volatilized pollutants from lawn treatments and driveway sealants. If installing a new driveway, choose anything but blacktop. If you have inherited a blacktop driveway, choose asphalt, not coal-tar sealants. Not only are the PAHs (polycyclic aromatic hydrocarbons) a major contaminant of local rivers; they are linked to serious health consequences like cancer and birth defects and found at high levels in homes that use coal-tar sealants. It makes me cringe when I remember that we used this product around Katherine. No one wants regrets like ours. The USGS (United States Geological Survey) has the best information on coal-tar sealants; they find that

  • Dust from pavement with coal-tar-based sealcoat has greatly elevated PAH concentrations compared to dust from unsealed pavement.
  • Coal-tar-based sealcoat is the largest source of PAH contamination to 40 urban lakes studied, accounting for one-half of all PAH inputs.
  • Coal-tar-based sealcoat use is the primary cause of upward trends in PAHs, since the 1960s, in urban lake sediment.
  • Residences adjacent to parking lots with coal-tar-based sealcoat have PAH concentrations in house dust that are 25 times higher than those in house dust in residences adjacent to parking lots without coal-tar- based sealcoat.
  • PAHs move from a sealcoated surface into our environment by many mechanisms: storm runoff, adhesion to tires, wind, foot traffic, and volatilization.

You can learn more at And be prepared for disinformation from the industry. Last year, Benedictine hosted a small event with USGS scientists on this subject. Industry hacks and their lawyers followed this scientist from one speaking event to another, asking misleading questions and trying to dominate conversation. I had never before seen in action the deliberate effort to create doubt about health effects as a way to confuse consumers.