The study of parking lot surfaces by the USGS and the City of Austin show that abraded sealcoat could be a major source of polycyclic aromatic hydrocarbons (PAHs) to urban and suburban water bodies in watersheds across the nation where sealcoat is used. To address PAH contamination in streams, the City of Austin Council banned the use of coal-tar based sealcoat, effective January 2006.

USGS Fact Sheet 2005-3147, Parking Lot Sealcoat: A Major Source of Polycyclic Aromatic Hydrocarbons (PAHs) in Urban and Suburban Environments