Last week Washington State became the third major US jurisdiction, after the City of Austin and Washington DC, to ban the use of coal tar based sealants on roads and driveways. The concern arises from the high level of Polycyclic Aromatic Hydrocarbons, a family of substances which includes known or suspected carcinogens and mutagens, which is contained in such sealants. There is some evidence that the PAHs can flush from treated surfaces into nearby surface waters.
The decision to ban coal tar sealants was made by the State Legislature when it passed House Bill 1721 An Act Relating to Preventing Storm Water Pollution From Coal Tar Sealants.
The legislation bans the wholesale or retail sale of coal tar pavement products after January 1st, 2012 and bans the use of such products after July 1st 2012.
The Bill was introduced by Washington State Representative David Frockt (Democrat), first elected to the Legislature in 2010 with support from the Sierra Club and Conservation Voters.
The text of the short bill may be found at http://e-lobbyist.com/gaits/WA/HB1721
Evidence from the United States Geological Survey against coal tar based sealcoats can be found at http://water.usgs.gov/nawqa/asphalt_sealers.html