Ending the Use of Tar-Based Sealants
Tar-based pavement sealants are the primary source of toxic PAH pollution in urban landscapes. Those PAHs are harmful to human health, and hurt fish and other aquatic life in our lakes and rivers. Clean Wisconsin is a leading voice on this issue, and will continue to encourage municipalities and the state to find solutions to this challenge.
What are pavement sealants?
Pavement sealants, also known as “sealcoats” or “sealers,” are the jet-black coatings homeowners and contractors apply to residential, commercial, and industrial driveways and parking lots. There are two main types of pavement sealants on the market today: tar-based sealants (also called “coal tar-based”), and asphalt-based sealants.
What's the problem with tar-based pavement sealants?
Pavement sealants contain polycyclic aromatic hydrocarbons (PAHs), which are toxic compounds that can cause cancer and developmental problems in children. The American Medical Association and other public health groups have urged local and state governments to ban tar-based sealants due to their harmful health effects.
How are people exposed to PAHs from tar-based sealants?
PAHs accumulate in soils, household dust, and carpets when particles of tar-based sealants are blown or tracked into homes, schools, and other buildings. The particles come from those sealants being worn down over time by weather, tire abrasion, and foot traffic. The toxic sealant particles are also washed off by rain and spring meltwater, ending up in our local water bodies.
How significant is the health risk?
The coal tar pitch used in tar-based sealants is classified as a hazardous waste. Children living in homes where parking lots are coated with tar-based pavement sealants face a 14-fold increase in cancer risk compared to those living next to unsealed lots, according to researchers at Baylor University and the U.S. Geological Survey. A lifetime of exposure can lead to cancer rates 38 times higher than normal.
What are the environmental impacts of PAHs?
PAHs kill small organisms living on the bottoms of rivers and streams and can cause tumors in fish and other large aquatic animals. This could result in costly impacts on the ecological balance of aquatic environments. Even three months or more after sealants are applied, the tar-sealed pavement runoff can kill fathead minnows and water fleas, two indicator species used to assess chemical toxicity to aquatic life.
times higher lifetime cancer risk for children living from birth to age 6 near parking lots with tar-based sealants
What are the economic impacts of PAHs?
PAH pollution from tar-based sealants can be a significant burden to taxpayers when municipalities are on the hook for cleaning up stormwater sediment ponds contaminated with PAH-laden sediment. In the Minneapolis metro area, the PAH cleanup from tar-based sealants is estimated to cost taxpayers hundreds of millions of dollars.
Are there alternatives?
Yes! Asphalt-based pavement sealants have up to 1,000 times lower PAH levels and are no more expensive than tar-based sealants. Alternatives such as acrylic sealants or gravel parking lots and driveways have minimal PAH levels. Studies of an early PAH ban in Austin, Texas, have shown significant PAH reductions in local waterbodies.
How do tar-based sealants compare to other PAH sources?
Other sources of environmental PAH pollution have significantly lower concentrations than tar-based sealants. Fresh asphalt, for example is about 1.5 parts per million (ppm) PAHs. Smoke from wood fires can range from 2 to 114 ppm, engine exhaust 102-370 ppm, and used motor oil around 440 ppm. Tar-based sealants are hundreds to thousands of times worse, at 70,000 – 100,000 ppm.
Where have tar-based sealants been banned in Wisconsin so far?
13 communities and one county in Wisconsin have banned tar-based sealants: Dane County, Milwaukee, Glendale, Franklin, Brown Deer, Elm Grove, Shorewood, Whitefish Bay, Port Washington, Greenfield, West Allis, Bayside, Hales Corners, Wauwatosa.
Where have tar-based sealants been banned elsewhere in the U.S.?
A handful of states and dozens of communities have banned tar-based sealants, including: States of Minnesota and Washington; Ann Arbor, MI; Annapolis, MD; Austin, TX; Evanston, IL; Greenville, SC; Grosse Ile, MI; Matthews, NC; San Antonio, TX; Washington, DC; Wilmette, IL; Winfield, KS; Winnetka, IL; Ypsilanti, MI
How to be PAH-safe:
Don’t use tar-based pavement sealants
If you feel you must seal your driveway or parking lot, then use asphalt-based sealants, which have 1,000-times lower PAH levels.
Remove your shoes
If you don’t have control over your parking lot or driveway, try to keep sealant dust and soil out of your house by taking off shoes before entering your home or apartment.
Look for hidden PAHs
Tar can have a lot of different names, and some other byproducts can have very high levels of PAHs. To be safe, check the “Material Safety Data Sheet” of the product (try searching online) and avoid anything including CAS #’s 64742-90-1, 65996-92-1, 65996-93-2, 65996-89-6, 69013-21-4, or 8007-45-2.
Become an advocate in your community against the use of tar-based pavement sealants.