By David J. Wilson
Van Buren Township
During the last few years much research has come out showing that coal tar-based driveway sealers are a significant threat to our health and the health of our children and that they cause substantial damage to fish and other aquatic life.
This research comes from the US Geological Survey Texas Water Science Center, the Minnesota Pollution Control Agency, Baylor University, the University of New Hampshire, and Missouri State University.
It has been presented in highly regarded professional peer-reviewed journals such as Environmental Science & Technology, Environmental Pollution, Chemosphere, and Science of the Total Environment, and in reports published by the US Environmental Protection Agency.
This is not junk science.
I am not talking about a disastrous emergency; the gutters are not running red with blood, and there are no corpses lying in the streets. On the other hand, all indications are that we can reduce cancer risk a bit, particularly among children, and we can improve the quality of our streams substantially by switching from coal tar-based driveway sealers to other, readily available alternatives.
First a little background on driveway sealers in general. There are several types of these: Coal tar-based, Asphalt-based, Latex, and Others (acrylic, etc.) Of these, those based on coal tar and asphalt are the most widely used. Coal tar-based sealers contain coal tar, a product of the production of coke from coal for use in steel manufacture. Asphalt-based sealers contain asphalt, a product of oil refining operations. We are particularly concerned about the PAH (polycyclic aromatic hydrocarbon) contents of the various sealers, as a number of PAH compounds are carcinogenic, teratogenic (cause birth defects), mutagenic, and toxic.
“Latex and Others” sealers contain no PAHs. Coal tar-based sealers contain roughly 5-10% PAHs. Asphalt-based sealers contain about 1/1,000 times the PAH content of coal tar-based sealers, 0.005–0.01%. Evidently the use of coal tar-based sealers has the potential to be a
significant environmental problem.
The impacts of PAHs on aquatic life are as follows. Fish: fin erosion, liver abnormalities, cataracts, skin tumors, increased susceptibility to disease. Amphibians: stunted growth, delayed development, difficulty swimming, liver problems. Benthic macroinvertebrates: degradation of cell membranes, inhibited reproduction, delayed emergence, mortality. We need to keep these PAHs out of our storm drains and streams.
For humans, these compounds are powerful mutagens, carcinogens, and teratogens. They are correlated with lower IQ, childhood asthma, low birth weight, premature delivery, heart malformations, and developmental delays. Coal tar is a powerful mutagen.
A major driveway sealer PAH exposure pathway for humans is as follows. Weathering and tire abrasion convert coal tar-based sealer to a PAH-rich dust. This washes down storm drains, is blown onto nearby pavement and soil, and gets tracked into homes, becoming house dust. Incidental ingestion of soil and dust, especially by children, is a major route of human exposure. You get about 38 times more PAH if you live next to coal tar-seal-coated pavement than if you don’t, and your lifetime cancer risk from PAHs is 38 times as great. The estimated excess cancer risk is greater than 1 in 10,000.
Atmospheric emission of PAHs from treated pavement is about twice that from vehicle emissions, the second largest source of atmospheric PAHs.
PAHs from driveway sealer can be a costly problem in disposing of sediments accumulating in storm water management basins. In a suburb of St. Paul, MN, the sediments of three out of 12 such basins were found to contain high enough concentrations of PAHs to make these sediments hazardous wastes, requiring that they be disposed of in a hazardous waste landfill, which greatly increases the cost of basin maintenance. Austin, TX, found PAH concentrations in sediments greater than 1500 mg/kg in some small drainage areas in residential areas. For comparison, the PEC (probable effect concentration) of PAHs is 23 mg/kg.
A number of government bodies have already banned the use of coal tar-based driveway sealers. These include Washington State; Minnesota; Washington, D.C.; Greenville, SC; Austin, TX; Montgomery Co., MD; Suffolk Co., NY; Dane Co, WI; and the Edwards Aquifer, TX. The University of Michigan has also banned their use.
Non-coal tar alternatives are readily available. A check on the internet indicated that Lowes, Sears, and Home Depot all carry alternative sealers. A list from the Minnesota Pollution Control Agency adds Ace Hardware, Do It Best, and True Value Hardware to the list.
What we can do
What can we as citizens do about this hazard to our health and that of our children?
First, if you use driveway sealer, make sure that the bucket label clearly indicates that the sealer is NOT coal tar-based. If you have your driveway sealed commercially, get assurance from the company that it is not using coal tar-based sealer. Urge your neighbors to do likewise.
Second, seek resolutions from the Van Buren Township trustees and from the City of Belleville urging against the use of coal tar-based driveway sealers.
Third, seek placement of a brochure on the hazards of coal tar-based driveway sealer in the township and city offices for public distribution.
Fourth, urge the township, the school district, and the city to ban the use of coal tar-based sealers on their property and/or by their employees.
Fifth, seek ordinances banning the use of this material in Van Buren Township and the City of Belleville.
Please join me in attempting to eliminate this hazard to our environment, ourselves, and our children.
Weather