javascript:; Thin Asphalt Coating in the Thick of Chemical Exposure | Coal Tar Free America

Common Pavement Preservative a Potent Source of Carcinogens & Toxins

Our lives are so filled with paved surfaces. They are a familiar symbol of our evolution out of the grit and grime of development. They improve property values and make getting around a faster, more pleasant experience. Yet, most have no idea how damaging one ingredient can be. If you did, then you would never cross a pavement in the same way again.

Over the last decade or so research has exposed just how harmful coal tar containing pavement products are. Coal tar sealers are a thin, black top coating to beautify and protect asphalt driveways, parking lots and playgrounds. It smells kind of like telephone poles or moth balls or that nasty odor of coal tar shampoo. Every year we spread enough coal tar sealer in the United States to coat a 26-lane highway from New York to Los Angeles. Unfortunately it isn't coating some theoretical superhighway, but the asphalt surfaces where you live, work and play.

In 2007, two of the nation’s largest home improvement retailers quietly phased out the sale of buckets of coal tar sealer with no encouragement from any environmental organization. What did they realize that the rest of the country hasn't awakened to?

Toxicologist: Likely Large Number of Americans with Cancer from Sealers

The chemical family of concern with coal tar pavement sealcoat is polycyclic aromatic hydrocarbons (PAHs). Most often they are associated with automobile exhaust, wood burning fireplaces, grilled meat and cigarette smoking.

Most toxins in our food and environment are on the order of a few parts per million or billion, but coal tar sealers are at levels 1,000 of times more (and as much as 7%!). The US Geological Survey calculated that the emissions from curing of coal tar sealed surfaces are more than all US vehicle emissions! These airborne chemicals have been shown to trigger asthma attacks too.

Dr. Spencer Williams of Baylor University was one of the first toxicologists to study the risks of exposure to the dust from this product as it wears off and can be tracked into homes. His conclusion:

"The increased cancer risk associated with coal-tar-sealed asphalt likely affects a large number of people in the U.S. Exposure to these compounds in settled house dust is a particularly important source of risk for children younger than six years of age, as they are expected to ingest this material at higher rates."

What are Other Effects?

A recent article on the Safer Chemicals, Healthy Families' website showed a broad range of chemicals which modify the brain's development. One of those chemical families is PAHs which can lower IQ and birth weight of the unborn, while raising the risks for obesity and behavioral disorders.

How Big is the Risk?

Dr. Williams found the risk to be greater than 1 in 10,000 lifetime risk of developing cancer, which is about the same as home exposure to secondhand cigarette smoke.  This exceeds a federal standard for some kind of cleanup or action. We wouldn't tolerate secondhand smoke exposure at school, but we unknowingly allow our nation's school playgrounds and sport courts to be covered with coal tar sealers.

What about the EPA?

Just like so many of the chemicals in the US marketplace, the EPA lacks the leadership to address this problem head-on. However, they have studied this product and found that it is indeed toxic; have written fliers to inform the public; and have even given grants to agencies to encourage the reduction of its use.


The States of Washington and Minnesota have banned these products as have communities across the country. However these bans only cover about 5% of the US population. National ban legislation has been introduced in Congress, but there hasn't been enough attention to this problem for it even to be heard in committee.

Grassroot efforts will be necessary to rid our nation of this product. Readers are encouraged to learn where they are exposed and press for non-coal tar containing products or bans wherever possible. Contact me or read this post if you would like to learn more.

Coal Tar Free America is a blog site that I started 5 years ago to educate and advocate for changes to our nation's use of this polluting product. Previously I managed the effort to pass and enforce the nation's first ban of coal tar pavement sealers in Austin, Texas.

Please take a little time here on this site and others to learn what you can do to limit this exposure to your family and your community.

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