Sudbury Experience – Coal Tar Sealants
September 17, 2018
Driveway sealants have been used for more than 50 years to keep driveways from cracking and to keep that shiny, smooth look. Industry representatives say that their products are safe but recent studies by the U.S. Geological Survey, Baylor University, USEPA, and University of New Hampshire indicate otherwise. These studies all show that coal-tar based sealants contain up to 25% higher levels of toxic compounds called PAHs (polyaromatic hydrocarbons). PAHs are toxic to fish with a number of the compounds deemed hazardous to humans and potential cancer threats. These compounds are also known pollutants to waterways. The product gradually wears off the driveway or parking lot surfaces and the breakdown of PAH enter our homes by wind as a dust. This dust can be inhaled and by tracked inside on our shoes. It enters our rivers and streams through rainwater runoff into storm drain.
Coal tar is a by-product of coke ovens used in the steel manufacturing industry. Coal tar based sealants contain 20% coal tar. An alternative, petroleum based sealants, contain only 0.7% PAHs and use very little or no coal tar. Petroleum-based sealants are not without environmental consequences but are not nearly as toxic as the coal-tar based products.
It is for these reasons that the Town of Sudbury has adopted regulations banning the use of coal tar sealants within areas subject to wetland jurisdiction and on sites where a local stormwater management permit is required. This includes any repaving or resurfacing projects that exceed 500 sq. ft. In Sudbury, as is the case is many of our surrounding towns, we depend on public or private groundwater wells for our drinking water. Reducing the amount and type of pollutants, including PAHs, that enter our groundwater is important for the health of all our human, fauna, fish, and avian residents.
Is that shiny black driveway really worth the harm? To help keep your family and the local wildlife safe, before sealing your driveway hire only a contractor who provides a MSDS (material data safety sheet) for the intended product. Check to see if it contains this CAS number for coal tar: 65996-93-2. If doing the work yourself, buy only products with a “coal tar free” logo.