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Tales From the Front: What Coal Tar Contractors are Telling Their Customers

A letter is being circulated around among contractors that continue to use coal tar sealants. They use it to convince their customers to co...

A letter is being circulated around among contractors that continue to use coal tar sealants. They use it to convince their customers to continue to use this toxic product.  Isn't it amazing that this was the most read article among sealcoating contractors in 2012 and 2013? 

It was written from a contractor to his client to assure the client that all this talk about coal tar sealant pollution is bunk. In my opinion this is the chaos that is created when our regulatory agencies don't step up and show leadership that their own research shows is a problem. Until that happens, we will continue to challenge flabby thinking on this issue.

When I first read this letter on the Paveman Pro website, I wrote a response to be published on this website, but the editor felt that my response was too personal and would not publish it.  My intent was to be respectful but straightforward. Apparently it was too straightforward!

Well I guess that is what a blog is for! My intent is not to make personal attacks, but to show the fallacy of the arguments made.

If you don't want to wade into this point-by-point, then let's here's my summary. This letter is full of the following:

  • Exaggerations
  • Understatements
  • Concealments
  • Equivocations (the use of a vague expressions, especially in order to mislead):
  • False statements
It's a pretty sad reality if this is what it takes to sell your product.

What follows is a point-point response to the comments made by the contractor. The original text of the letter is in italics and Coal Tar Free America's response is in bold. The main point being responded to is highlighted. Some of the comments have links so then click the text and you'll go to the link.

Dear John,

I know there is somewhat of a controversy brewing regarding the safety of coal tar sealer in relation to the environment and humans, and this is not the first time I've had to address this issue. 

With bans popping up all over the nation, I think we are beyond the "brewing" stage!

Let me start by stating that I have been in this industry since 1980, and started Asphalt Enterprises in 1983. There aren't too many contractors in the United States who have been responsible for more gallons of coal tar sealer applied than myself, and we are the number one applicator in the Atlanta area, and have been for years. Let me also state that I have no dog in this fight, that is, coal tar sealer vs. asphalt emulsion sealer, since we can apply either material, and have applied a fair amount of asphalt emulsion sealer in the past. 

This is a false statement. Yes you don't have a dog in this hunt. You have TWO: Pride & Money. If what the environmentalists have been saying is true, then your pride may resist that for 32 years your efforts, which may be innocent, have been responsible for environmental and economic harm. 

What I like to look at are the facts, based on unbiased, untainted scientific studies, and also common sense and my years of experience. 

This is a false statement. Really? Facts? Many of these points are based in "myths" not facts. Here are some common sealer myths debunked:
  1. Myth of "controversial" coal tar sealant science.
  2. Myth that the ban in Austin had no effect.
  3. Myth of "flawed" USGS studies.
Unbiased? The only research that dismisses the impacts of coal tar sealers is industry-sponsored. Industry-hired research does not meet the standard as set by the National Academy of Sciences concerning a conflict of interest (Conflict of interest is defined as any financial or other interest which conflicts with the service of an individual because it could impair the individual's objectivity...).

Also as a side note, all pavement coatings manufacturers produce both coal tar sealer and asphalt emulsion sealer, so actually their studies are also unbiased. They are just convinced, and rightfully so, that coal tar sealer is a superior pavement coating.

This is a concealment. Just because someone manufacturers both kinds of products does not make them unbiased. Sealant manufacturers may be biased for a number of reasons including equipment infrastructure, quality of their products, liability, supply chain, profitability, etc..  

Environmentalists recently have upped their efforts on having coal tar sealer banned, based mainly on the results of two studies , one in Austin, Texas, and the other performed by the U.S. Geological Survey. 

This is a concealment and means to imply that there is limited information on this issue. There are close to 25 scientific publications that include coal tar sealants and they have been done by local agencies, universities, the USGS, the EPA, states, and a division of the Centers for Disease Control. There were just 2 studies 7 years ago, but much has changed since then. Links and abstracts of most of the studies can be found at this post on this site: Human Health, Coal Tar Sealants, & PAHs: the State of the Science

Unfortunately for the environmentalists, both studies have been proven to be flawed by independent researchers. Please visit the following links for a more detailed explanation of the flawed studies.

I did a post about that entitled, The Myth of Flawed USGS Studies, which traces the origin of these mis-statements. 

In 2010, Springfield, Missouri tried to have a ban placed on coal tar sealer, and put it in front of the city council for a vote. Below is a link to a letter submitted by a property developer who owns shopping centers in Missouri, trying to convince the city council to reject the ban. This developer had very positive experiences with coal tar sealer, and very negative experiences with asphalt emulsion sealer (I'll touch on that below). By the way, the ban was rejected.

While it is true that Springfield did vote against a ban in 2010, here's an update. The University of Missouri and the City of Springfield did a joint study and found coal tar sealants are a pervasive stream pollutant there. The ban may be revisited as a result.

The developer comment is a concealment. The developer had this experience more than a decade ago in the infancy of asphalt-based sealer development. That's like saying "I'm not going to get one of those cell phones because I used one 20 years ago and it weighed over 10 pounds!"

John, as you can see there has been a huge "rush to judgement" regarding the banning of coal tar sealer. 

One of the city council members who voted against the ban made very good sense when she stated that she heard evidence from Phd's stating that coal tar sealer was harmful, and she heard evidence from Phd's stating that it was not harmful and they provided the research to prove it was not harmful. In the end she said there was no compelling evidence to believe that coal tar was harmful.

While people may disagree on what a "rush" is, but dozens of studies, by multiple scientists, throughout the nation, over nearly a decade now, is no "rush" to judgment in my opinion.

This same Springfield councilwoman said in the local newspaper, “I think this (University of Missouri Study) makes it clear that coal tar is the problem,” she said. “Now the question becomes, what are we gonna do about it?"

Let me just take a minute to explain the difference between coal tar sealer and asphalt emulsions. Coal tar sealer has been around for over 60 years, and coal tar was chosen over asphalt emulsion as a better raw material based on its ability to prevent the intrusion of gas, oil, and other petroleum products from damaging the pavement, and the very hard film that coal tar forms over the pavement, making it very durable to heavy traffic. Asphalt emulsions are used as a raw material in sealer only as a substitute, in areas where coal tar is not available, and has proven to be an inferior substitute . Asphalt emulsion sealers only last a couple of years, only one coat can be applied in a day, wash out areas are very common.

Where was this "proven?" Both asphalt-based sealers and coal tar sealants vary dramatically in quality and price. I have seen asphalt-based sealcoat outperform, in all aspects, coal tar sealants. Here's more information about the acceptability of alternative products to coal tar sealers:
  1. Asphalt sealers preferred for pavement maintenance by #1 think tank for asphalt, the Asphalt Institute.
  2. The FAA has written asphalt-based sealers into the new federal specification for airports.
  3. Some asphalt sealers are more fuel resistant than coal tar sealers.
In closing I just want to state some facts regarding coal tar:

- The FDA has approved coal tar for decades as a base ingredient for skin creams and shampoos that fight certain skin conditions. It is very odd that the FDA would approve coal tar to be applied to the skin and scalp IF it was harmful. The amount of PAH's produced by these items is far higher than that in coal tar sealer. Not sure why the environmentalists aren't fighting the FDA and pharmacuetical companies to have coal tar banned from skin creams and shampoos. This fact ALONE should dispell any belief that coal tar sealer is harmful.

Coal tar shampoo is a common dodge by the industry. There is a huge difference between a medicated product used in a controlled manner versus a pavement product that as it cures and wears indiscriminately exposes children, adults and the environment. In the same way, radiation therapy is a valid approach to treating cancer, but just because that is true, does not make putting radioactive iodine on parking lots necessarily safe.

- In the over 60 years that coal tar sealer has been used, there is no study that shows any harmful affects to humans or animal life attributed to coal tar sealer.

I recognize you are busy but have you actually read the any of the studies that show this product harms aquatic organisms? Here's a list with concluding summary:

The effects of coal tar based pavement sealer on amphibian development and metamorphosis. 2006. Bryer, P.J., Elliott, J.N., and Willingham, E.J. , Ecotoxicology, vol. 15(3), 241-247. 
This scientific journal article reports that exposure to sediment contaminated with coal-tar-based pavement sealer resulted in stunted growth and slower development of the frog Xenopus laevis. 
Coal-tar based pavement sealant toxicity to freshwater macroinvertebrates. Bryer, P.J., Scoggins, M., and McClintock, N.L., 2009. Environmental Pollution, v. 158, no. 5, p. 1932-1937. 
This scientific journal article reports that exposure to sediment contaminated with coal-tar-based sealcoat resulted in decreased abundance and richness of freshwater macroinvertebrates, an important element in the aquatic food chain. 
Occurrence of polycyclic aromatic hydrocarbons below coal-tar-sealed parking lots and effects on stream benthic macroinvertebrate communities. Scoggins, M., McClintock, N., Gosselink, L., and Bryer, P., 2007. Journal of the North American Benthological Society, v. 26, no. 4, p. 694-707. 
This scientific journal article reports a significant decrease in the health of the ecological community downstream from points of discharge of runoff from coal-tar-sealcoated parking lots relative to ecological communities upstream. 
Toxicity of coal—tar and asphalt sealants to eastern newts, Notophthalmus viridescens. 2010. Bommarito, T., Spading, D.W., and Halbrook, R.S. 
This scientific journal article reports that exposure of eastern newts to sediment contaminated with coal-tar­based sealcoat resulted in deleterious effects, including difficulty right themselves, impaired ability to swim, and diminished liver enzyme activities. 

Toxicity of coal-tar pavement sealants and ultraviolet radiation to Ambystoma Maculatwn. 2010. Bommarito, T., Sparling, D.W., and Halbrook, R.W. 

This scientific journal articles reports that spotted salamanders exposed to sediment contaminated with coal-tar-based sealcoat in sediment had slower rates of growth and diminished ability to swim. Subsequent exposure to ultra-violet radiation resulted in genetic damage.
 -Coal tar sealer is NOT and has NEVER been classified as a hazardous material by the EPA.

This is a concealment. The active ingredient in coal tar sealants is coal tar pitch, which has something like a serial code definition called a "chemical abstract service" or CAS number. For coal tar pitch it is CAS No: 65996-93-2. 

According to the USEPA, "Coal tar emulsion sealants can contain up to 35% refined coal tar, which is made up of 50% PAHs by mass (NIST 2006)." "PAHs are known carcinogens and are known to be toxic to aquatic life (EPA 1984; Long and Morgan 2000; and Ankley et al., 2003)."

The International Agency for Research on Cancer (IARC) states the following:
  • Evidence for carcinogenicity to humans (sufficient)
  • Evidence for carcinogenicity to animals (sufficient)
  • Summary evidence: Coal-tars are carcinogenic to humans
-Asphalt emulsions also produce PAH's, and in fact, since asphalt emulsion wears faster than coal tar sealer, these PAH's are released into the storm drains and streams at a faster rate

This is a false statement. Because of the exceptional concentration of PAH in coal tar sealants compared to asphalt-based sealers, an asphalt sealant would have to wear off and be re-applied every day to be equivalent to the potency of a coal tar sealer. How is that figured? If a asphalt sealer has 1,000 times less PAHs than coal tar and coal tar lasts about 3 years (about 1,000 days), then the asphalt-based sealer would have to be applied 1000 times more often to equal the same loading.

Also PAH's in asphalt emulsions are lighter than those of coal tar sealer, thus they will stay afloat and wash further down stream, as opposed to coal tar PAH's which will fall rapidly, attaching to sediments, causing zero affect on PAH levels in the water. Other producers of PAH's include, tire wear residue, motor oil drippings, car exhaust, hot mix asphalt, jet exhaust, roof shingles, even cigarettes, outdoor grills, volcanos, and forest fires and other outdoor burning, even wood burning in home fireplaces.I'm afraid that the if the environmentalists are successful at banning coal tar sealer, their next step will be to ban asphalt emulsion sealer based on what I stated above. 

Since asphalt sealers are so much less harmful, this is extremely unlikely. 

What they don't realize is, banning sealants in the long run will have a much greater affect on the environment and natural resources. Pavement life will be decreased dramatically, requiring increased levels of asphalt replacement, overlayments, and total replacements. This will require more crude oil to manufacture the asphalt, more rock extracted from our rock quarries, more fuel to manufacture asphalt and raw materials, not to mention the performance of this work. Most asphalt pavements will need to be replaced within 10 years. 

Did you know that studies have shown that coal tar sealers degrade asphalt and that it isn't recommended by the leading association for pavement quality in the United States?

As an owner and investor in shopping centers, this will also place a financial burden on companies like yours and their investors, not the mention the lack of "curb appeal" which attracts customers to a freshly sealed and well maintained parking lot.

Really concerned about the financial burden of the owner? What is the potential cost and liability of cleaning up a parking lot which exceeds federal safety standards for human exposure?

Are we willing to attract customers by putting hazardous material on our properties? Would they be so excited to go to these commercial businesses if they knew what is on the parking lot? Today's asphalt-based sealant stays black for the life of the product. However with as much as 30% of our urban surfaces heat-absorbing black, perhaps it's time for us to move beyond the black paving aesthetic.

With my 32 years working in the sealcoating and paving industry, I have not seen any credible studies showing that coal tar sealer is harmful to humans or the environment. And without hesitation, if I saw any compelling, unbiased study showing it was harmful, I would discontinue it's use within my company immediately.

Thank you John for taking the time to read this, and hopefully it will make a change on how coal tar sealer is viewed.


Gerry L. Signs
Asphalt Enterprises, Inc.

There is a ground-swell of sealant contractors that no longer buy that coal tar sealants are harmless and they are switching to asphalt-based sealants. Now is the time for us to freshly look at new information and not be fearful of the future or defensive about past, out-dated practices.


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Coal Tar Free America: Tales From the Front: What Coal Tar Contractors are Telling Their Customers
Tales From the Front: What Coal Tar Contractors are Telling Their Customers
Coal Tar Free America
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