By PATRICK LYONS
Capital News Service
LANSING — Legislators in Michigan and other Great Lakes states are proposing to ban coal-tar pavement sealants that kill aquatic animals and possible threaten human health.
Such bans are in place in 15 municipalities and two counties in Wisconsin, Minnesota, New York and Texas. Washington has a statewide prohibition.
Coal-tar sealant used primarily on parking lots made with coal-tar pitch, a human carcinogen, according to Environmental Science & Technology magazine.
The sealants contain polycyclic aromatic hydrocarbons – PAHs for short – some of which are considered probable human carcinogens by the Environmental Protection Agency.
Industry experts say there is insufficient scientific evidence that coal-tar sealants adversely affect people or wildlife.
But Rep. Dian Slavens, D-Canton Township, the sponsor of a ban bill, said, “With it being a carcinogen, I thought we should keep pursuing it so we can get this legislation pushed through.”
Slavens said she’s unsure what is holding up the legislation awaiting review in the House Committee on Regulatory Reform
“I have not heard from any groups, usually someone will call you up and say, ‘Why are you doing this?’” she said. “But I have not heard any negatives on my bill from any group.”
Coal-tar sealants release large amounts of PAHs into the environment during application. And as they erode, rain can wash them into lakes, rivers and streams.
That threatens both the Great Lakes watershed and human health, said Peter Van Metre, a research hydrologist for the U.S. Geological Survey in Austin, Texas.
PAHs don’t dissolve in water but build up in the sediment of lakes and streams in urban and suburban areas that receive runoff from parking lots sealed with coal-tar. Once in the watershed, they can cause mutations and birth defects in aquatic life, Van Metre said.
Levels have increased in the sediment of urban and suburban lakes since 2000 even when other major sources, like power plants, have cut emissions.
Negative effects on fish and other aquatic animals include inhibited reproduction, fin erosion, liver abnormalities, cataracts and death, according to Geological Survey reports.
There have been no studies on the negative human health effects of the sealant, Van Metre said. But because it contains multiple contaminants that cause cancer in other animals, it is a probable carcinogen for humans.
Because PAHs don’t dissolve in water, they don’t threaten the safety of drinking water, according to the Geological Survey. But people can absorb them through inhalation of wind-blown particles, ingestion of dust or skin contact.
The Environmental Health Perspectives Journal reported that prenatal exposure to high-levels of airborne PAHs can be linked to lower mental development at age 3. And Columbia University researchers found a correlation between high levels of prenatal exposure and obesity at ages 5 and 7. Neither study made a distinction about the source of PAHs or linked exposure directly to sealcoats.
Such studies have prompted legislators to propose bans of the coal-tar sealcoat in several states including Michigan, Illinois and New York. These bills remain in committee.
Anne LeHuray, executive director of the Pavement Coating Technology Council in Alexandria, Va., said the only real impact of a ban is to hurt small businesses.
“A ban would affect revenues, employment and it would have no environmental benefit; I feel that is pretty demonstrable,” she said.
“Local politicians in particular are being misled — they are always looking for something they can do for their constituents, and coal-tar sealants are being made out to be such a horrific source of PAHs and it’s not.”
She said the Geological Survey’s research has overblown the risk to human health and overstates the amount of PAHs produced by the sealants.
Activists exaggerate the danger to humans, LeHuray said, and no one in the industry is aware of an insurance claim for damages or health problems from sealcoats.
The Geological Survey is wrong on the amount of PAHs released as well, she said. A report from the Pavement Council on PAH releases in New York and New Jersey shows coal-tar sealant contributing only 0.4 percent of total PAHs.
That data is consistent with what Van Metre found in Great Lakes states.
“In the Great Lakes region, the high levels of PAHs are due to the region’s history of coal stoking and iron production, not parking lots,” he said.
But annually more PAHs are released into the environment by the application and wear of coal-tar sealcoat than from all vehicle emissions, said Van Metre.
Slavens said she wants to alert the public to a safer asphalt-based alternative that has 1,000 times fewer PAHs than coal-tar sealant.
But LeHuray said asphalt-based sealant doesn’t last as long, and as a petroleum product its price fluctuates with the price of oil. That unpredictability is why many applicators choose not to use it.
“Someone seals a parking lot to protect their underlying investment in the asphalt,” LeHuray said. “If you are using the regular coal-tar base sealer it only has to be redone every three to five years. If you are using the asphalt base sealer, you have to redo it every one to two years. And there hasn’t been a full scale study of how much environmental impact there is when one has to pave more often.”
Former CNS correspondent Patrick Lyons writes for Great Lakes Echo.
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