Great Lakes Advocates Highlight Growing Concern Over PAHs
By Anne Glausser
From toxic algae to Asian carp to sewer overflows, the Great Lakes have a number of different problems facing them. Presenters at this week’s Great Lakes Restoration Conference in Chicago will be discussing all of them, plus one lesser known threat to the waterways: a group of chemicals known as PAHs.
PAHs—or polycyclic aromatic hydrocarbons—haven’t gotten as much attention as other high-profile Great Lakes issues, but some lake advocates are trying to change that.
That’s because PAHs have been directly linked to mutations, mortality, and reproductive issues in fish and other aquatic life, says Rebecca Esselman with the Huron River Watershed Council in Michigan.
There’s less evidence that PAH’s affect human health but scientists are still concerned. "There are a couple of known carcinogens in PAHs," says Esselman.
PAHs settle into the sediment in streams and lakes. Studies discovered over half of all PAHs found in the Great Lakes region come from a single source: coal tar sealants. "It’s that nice black coating we get on our driveways and parking lots to maintain and beautify those surfaces," says Esselman.
As that sealant wears down, PAHs can be swept by heavy rains into nearby soils and waterways.
The science has been building on this for the last decade, says Esselman, and some cities as well as the state of Minnesota have enacted bans on coal tar sealants. Less toxic asphalt-based alternatives are available and have been adopted by some contractors and companies.
Ohio has no bans on coal-tar sealants, and industry groups say bans would do little to eliminate toxic chemicals in the environment.
USGS Coal-Tar Sealant Research
Huron River Watershed Council’s Coal Tar Sealant Page