112 Algonquin Road
Barrington Hills, Illinois 60010
847.381.7871
www.bacog.org
What is Coal Tar?
Coal tar is an industrial waste, the sludge left over from coking coal in steel production. In 1992, the U.S.
EPA ruled that it would not be classified as a hazardous waste, even though it is a known carcinogen1,
because it could be “recycled” for uses including coating asphalt.
Coal tar based sealcoats are one of the options for applying on asphalt driveways, playgrounds and
parking lots for protecting them from weathering and maintaining a dark, glossy appearance. Coal tar
contains a high level of polycyclic aromatic hydrocarbons (PAHs) a class of chemical organic compounds,
several of which are very toxic. Prolonged exposure to the PAHs in coal tar are hazardous to human
health, animal health and aquatic health whether ingested, inhaled or absorbed through the skin.2
Why the Concern about Coal Tar?
Coal tar sealants are mobile. Their PAH contents do not stay where they are applied. The sealants flake
off with vehicle, people and pet traffic and sunlight. People and pets can track coal tar dust into homes,
and the dust can be transported by wind and rain. Residences adjacent to parking lots with coal tar
based sealcoats have PAH concentrations in house dust 25 times higher than residences adjacent to
parking lots without coal tar sealants.3,4 In Lake-in-the-Hills, U.S. Geological Survey researchers found
that coal tar sealed driveway dust was contaminated with extremely high levels of benzo[a]pyrene, one
of the most toxic PAHs. The amount was 5,300 times higher than the levels that trigger an EPA
Superfund cleanup at polluted industrial sites.5 Models suggest that over a lifetime the risk for
contracting cancer can increase 38 times from just the increased ingestion of coal tar dust, not including
the additional impacts from skin contact or inhalation. Exposure for children under 6 years of age
carries the greatest risk. 6
Coal tar particles can also wash off in rain storms, and contaminate rivers and streams, significantly
affecting fish and other aquatic life. Effects can include inhibited reproduction, delayed development,
DNA damage, poor reflexes, tumors, cataracts, liver damage and death. There is documented impact on
aquatic variety as well as reduced populations.7,8 Coal tar flakes tend to bond with particles and fall to
the bottom of waterways as sediment. This means groundwater supplies are generally safe. However,
communities that gather their public water supplies from streams and rivers should be aware of
potential contaminants, especially after storms.
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What Are the Alternatives?
Use asphalt-based sealants. The asphalt based emulsions have significantly fewer PAHs than coal tar, on
the order of 1/1000th in USGS testing. 9 Asphalt based sealants are sold in most home improvement
stores. If you use a driveway sealer service, be sure to ask what they are using, and specify the use of an
asphalt-emulsion sealant. If the Chemical Abstract Service number for coal tar (65996-93-2) is on the
contents list for a driveway sealant, do not use it; it has coal tar.
Residents may choose to leave their driveways unsealed or to replace asphalt with concrete, pavers, or
other surfaces other than asphalt.
What Else is Being Done?
Some states, cities and towns have banned the use of coal tar sealants, and others are following their
lead. The City of Austin, Texas, was the first city to ban the use of coal tar sealants in 2006, and they
have seen a decrease in the level of PAHs in their waterways. In Illinois, communities such as South
Barrington and Winnetka have banned it. McHenry and DuPage Counties have restrictions as well. Bans
and restrictions are generally linked with public education efforts. Some large retailers have decided not
to carry coal tar based sealants. Because coal tar sealants are still available at retail and through
contracting, however, it is important for owners who apply their own driveway sealants to read labels
and purchase products carefully, and for those who use driveway coating services to specify the type of
driveway sealant they want used.
Where Can I Learn More?
Check out the BACOG website at: www.BACOG.org
Notes:
1United
States Environmental Protection Agency, National Institute of Environmental Health Sciences, The U.S. Dpet. Of Health and Human
Services, Agency for Toxic Substances and Disease Registry, http://www.invw.org/content/new-studies-toxic-asphalt-sealants-threaten-kidscause-air-pollution (2/17/2012)
2
Ibid
3U.S. Geological Survey (2011). Coal-Tar-Based Pavement Sealcoat, Polycyclic Aromatic Hydrocarbons (PAHs), and Environmental Health.
4 Ibid.
5. U.S. Geological Survey (2013). You’re Standing on It! Health Risks of Coal-Tar Pavement Sealcoat.
6 Williams, E.S; Mahler, B.J.; Van Metre, P. C. Coal-tar pavement sealants might substantially increase children’s PAH exposures.
Environmental Pollution, 2012
7. Van Metre, P. Mahler, B. Scoggins, M. Hamilton, P. (2006). Parking Lot Sealcoat: A Major Source of Polycyclic Aromatic Hydrocarbons in
Urban and Suburban Environments/
8 U.S. Geological Survey (2011). Coal-Tar-Based Pavement Sealcoat, Polycyclic Aromatic Hydrocarbons (PAHs), and Environmental Health.
9 http://www.invw.org/content/new-studies-toxic-asphalt-sealants-threaten-kids-cause-air-pollution (2/17/2012)
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