Great Lakes lawmakers consider statewide bans on pavement sealants



U.S. Geological Survey researchers applying coal-tar sealant for an experiment. Credit: Barbara Mahler, USGS Research Hydrologist

By Patrick Lyons

Legislators in at least three Great Lakes states are proposing statewide bans of certain pavement sealants that have killed aquatic animals and are considered a possible health risk to humans.

Bans are already in place in 15 municipalities and two counties in four states; Minnesota, New York, Texas and Wisconsin. But the statewide bans appear on hold while experts argue over their effectiveness.

Coal-tar sealant is primarily used on parking lots in the eastern and mid United States. It is made with coal-tar pitch, a human carcinogen, according to Environmental Science & Technology magazine.

The sealants also contain Polycyclic Aromatic Hydrocarbons — called PAHs for short – some of which are considered probable human carcinogens by the Environmental Protection Agency.

Coal-tar sealants release large amounts of PAHs into the environment during application. And as the sealant erodes, rain can wash them into lakes, rivers and streams.

That threatens both the Great Lakes watershed and human health, said Peter Van Metre, research hydrologist for the United States Geological Survey.

The PAHs do not 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.

Negative effects on fish and other aquatic animals include inhibited reproduction, fin erosion, liver abnormalities, cataracts and death, according to Geological Survey reports.

Coal-tar sealcoat makes up about half of the PAHs in lake sediment, according to Environmental Science and Technology. It is why PAH levels have increased in the sediment of urban and suburban lakes since 2000 even when other major PAH producers, like power plants, have been decreasing emissions.

There have not been any studies on the negative effect of coal-tar sealant on human health, Van Metre said. But because it contains multiple contaminants that cause cancer in other animals it is a probable carcinogen for humans.

Because PAHs do not dissolve in water they do not pose a threat to the safety of drinking water, according to the

Researchers studying air quality and toxicity of runoff in a parking lot sealed with coal-tar. Credit: Barbara Mahler, USGS Research Hydrologist

Geological Survey report. But they can be absorbed by humans through inhalation of wind-blown particles, ingestion of dust or skin contact.

Geological Survey studies have found  dust in residences adjacent to parking lots finished with coal-tar sealants with PAH concentrations  25 times that of other homes.

The Environmental Health Perspectives Journal reported that prenatal exposure to high-levels of airborne PAHs can be linked to lower mental development at age three. And Columbia University researchers found a correlation between high levels of prenatal exposure to PAHs and obesity at age five and seven. Neither study made a distinction about the source of PAHs or linked exposure directly to sealcoats.

These recent 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. Only the state of Washington has approved a statewide ban.

Michigan state Rep. Dian Slavens, D-Canton Township,sponsored a ban after seeing similar legislation die last session.

“With it being a carcinogen, I thought we should keep pursuing it so we can get this legislation pushed through,” Slavens said.

She is unsure what is holding the legislation up once it gets to committee.

“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.”

Anne LeHuray, executive director of the Pavement Coating Technology Council, said the only real effect 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 sealers.

The danger to humans has been exaggerated by activists, LeHuray said. No one in the industry is aware of an insurance claim for damages or health effects from sealcoats.

The Geological Survey report is wrong on the amount of PAHs released as well, she said. A report from the Pavement Council on PAH releases within New York and New Jersey shows coal-tar sealant contributing only 0.4 percent of total PAHs.

This data is consistent with what Van Metre has 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.

Diagram showing the various ways in which coal-tar is spread from parking lots to the surrounding environment. Credit: Environmental Science and Technology Magazine.

Slavens said she wants to alert people of a safer asphalt-based alternative that has 1000 times fewer PAHs than the coal-tar sealant.

LeHuray said the asphalt based sealant does not last as long as coal-tar sealant and as a petroleum product its price fluctuates with the price of oil. This 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, whereas 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.”

Coal-tar sealants are used primarily east of the continental divide while the asphalt based sealant is used west of the divide, according to Environmental Science and Technology. More steel mills, which produce the coal-tar pitch in coking ovens and coal-tar distillation plants are located in the Mid-west and eastern United States, so those areas have historically had greater access the ingredients for coal-tar sealant. And the Environmental Science and Technology report estimates that 85 million gallons of coal-tar sealant are used in the U.S. annually.

The Pavement Coating Technology Council is not a lobbyist group, but they perform and collect research on the subject.

Watch scientists Pete Van Metre and Barbara Mahler analyze the release of Polycyclic Aromatic Hydrocarbons  from coal tar pavement sealant after applying it on a parking lot.

9 thoughts on “Great Lakes lawmakers consider statewide bans on pavement sealants

  1. Why hasn’t Michigan’s DEQ moved on this issue, or are they going to sweep the PAH’s under the carpet like they did the lead in Flint? One of our legislators should take this up as environmental and health issue that needs to be addressed.

  2. For someone who ends up getting an asthma attack when the smell is in the air from either production or application I think that until it effect you personally, or someone close to you, you think its a waste of time. Keep up the good work before this hurts more people, either by breathing it or by contaminating our waters. From someone who suffers, I thank you for your study.

  3. I have been in the asphalt maintenance business since 1980. Sealing asphalt absolutely extends the life NO QUESTION! Those commenting here that say otherwise are wrong. I used coal tar from 1980 to 1995 and was acitvely looking for a substitute during that time. In 1996 I stared using a good quality asphalt emulsion and have had great results with it. Coal tar is bad stuff and I never needed a scientist to tell me that, but was overjoyed when the studies proved what I already knew.
    Anne LeHuray of the Pavement Coatings Technology Council is doing the industry a diservice by defending coal tar and saying that you need to seal every one to two years with asphalt emulsion. I have 15 year experience with coal tar and 18 years experience with Asphalt emulsion which I have no problem getting 3 to 5 years life out of.
    I really have a problem with the PCTC supposedly being an advocate for the industry, but putting all their effort into defending the foul odored, toxic, carcinogenic, water-air-and soil polluting coal tar sealer. Who supports this organization and why?

  4. The comments here that bother me are ones saying that pavement sealer provides no benefit, and that sealed vs. unsealed last the same amount of time. That is just not true. Asphalt pavement left unsesealed degrades from the forces of UV light (oxidation) and water infiltration. It doesn’t happen in a year or even two, but you can plainly see the effects from one year to the next. Coal tar sealer is nasty stuff which I have gotten sick from breathing the fumes. Asphalt Emulsion sealer works fine to protect asphalt.

  5. Go dump a 5 gallon pail of coal tar sealer in a acre pond and watch all the fish die. If there is nothing bad in coal tar why does it kill the fish , why does coal tar sealant burn the heck out of human skin if it is so good for you, the odor is so bad , certainly is cause problems in the lungs. As far as other sealants not lasting as long , have to call that one out , coal tar wears off just as fast as AE sealants . I guess asbestos was a good product as well , should we go back to using it as an insulation ? Come on people , boils down to the coal tar industry not wanting to convert to AE. All about money, from what I understand its another product we import from china! I can attest that sealcoat vs not sealcoating Will make the difference between a 10 drive to a 25 year drive , for every 2 dollars you spend in maintenance , will save you 6 dollars down the road. So yes there have been studies showing benefits the asphalt , coal tar sealants actually crack your asphalt when applied to heavy

  6. I attended an in-depth presentation on the subject held for my board, which is considering its own ban. According to the research presented, there have been no studies demonstrating that pavement coating extend the life of the underlying pavement, and the difference in cost to applicators is modest.

    Those living in apartment buildings with coated pavement have substantially increased levels of atmospheric PAHs in and around the apartments -especially at face level and below over the coated pavement,and adjacent waterways have unacceptably high PAH levels. PAHs are one of the principle contaminants responsible for listing of some of the Great Lakes Areas of Concern.

  7. From what I understand, driveways and parking lots last the same amount of time whether they are sealed or not. The waste of money seems to be in having them sealed at all.

  8. What a waste of money. The only places banning coal tar are left wing environmental nutbag municipalities. Someone with a strong interest in asphalt based sealer (garbage compared to coal tar)is behind these studies & bans.

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