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This spring, the City of the Village of Clarkston adopted an ordinance that prohibits the use and sale of pavement sealant products containing greater than 0.1% Polycyclic Aromatic Hydrocarbons (PAHs) by weight, including coal tar-based sealant, in the City of the Village of Clarkston. The purpose of the ordinance is to promote the public health, safety, and general welfare of the Clarkston community, plus promote the protection of our natural assets such as the Clinton River, Mill Pond, Park Lake, Middle Lake, Deer Lake and other waterways of the Clinton River watershed. Protecting these waterways benefits everyone because it can enhance the environmental, recreational, cultural, and economic resources of the City and the entire community.
What is pavement sealant?Pavement sealant, or sealcoat, is a thick, black liquid that is sprayed or painted on asphalt pavements, such as driveways and parking lots. Pavement sealant manufacturers market sealants to both residential and commercial applicators to increase the longevity and improve the appearance of asphalt surfaces. Coal tar sealants have been identified as a major source of polycyclic aromatic hydrocarbons (PAHS) contamination, which is a major potential concern for human health and aquatic life.Most asphalt sealant products have either a coal tar base or asphalt base. Coal tar-based sealant is most commonly used in Michigan, and asphalt-based sealant is predominantly used in the western United States.Coal tar sealants contain high concentrations of PAHs, a known human carcinogen, or cancer-causing substance. Exposure to PAHs has been linked to increased risks of lung, skin, bladder and respiratory cancers, especially in young children. Water runoff from coal tar seal-coated pavement is acutely toxic to several aquatic species, and exposure to diluted runoff from coal tar seal-coated pavement can damage DNA, and can hinder DNA repair. DNA damage and impaired DNA repair can lead to mutations.How do PAHs get into the environmentOver time, driveways and parking lots that were sealed with coal tar sealants shed dust and flakes of sealant that contains high concentrations of PAHs. Car tires and snow plows break down the top sealant coat, those small pieces and dust can be blown into the air, mix with precipitation and water runoff and move into streams and lakes, be tracked into homes on the bottom of shoes and bare feet and form of household dust. PAHs tend to accumulate in stream and lake sediment, especially in waterways next to driveways and parking lots that had coal tar sealant applied.What can home and business owners do?Homeowners and business owners can eliminate sealcoating as a maintenance practice for asphalt surfaces or the resident or commercial applicator must use an asphalt-based sealcoat rather than coal tar sealcoat.