The sealant industry, presumably backed by some influential business and labor organizations, recently came out with a 2-page summary of why they think a coal tar sealant ban is a bad idea in Illinois. Those reasons are, for the most part, desperate retreads of old industry myths mired in the past with little basis in fact. Many have poor logic and false and unfounded statements. Is it really desperate? Read the responses below and be your own judge.
What follows are the claims made by industry in italics followed by a science-based response in bold. The complete text of the flyer can be found at: link.
FACTS ON SEALANTS AND POLYCYCLIC AROMATIC HYDROCARBONS (PAHs):
- Coal tar is commonly used in medicinal products, such as dandruff shampoos, psoriasis and eczema treatments. It is also used to seal drinking water pipes as it is insoluble in water.
This statement is generally true, but irrelevant. Just because a material is used as a medicine does not mean it is OK to cast it into 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.
- PAH’s are a group of more than 100 chemical compounds that are everywhere in the environment in such diverse sources as: auto exhaust, motor oil, industrial processes, electric power generation, wood and yard waste burning, and even barbeque grilling. PAH’s from these sealants typically account for less than one half of a percent (0.4%) of what is found in the environment.
While it is true that “PAHs are a group of more than 100 chemical compounds,” the important fact here is that the most potent, urban source, illustrated in the following graphic from the USGS, is coal tar pavement sealant. Yes there are many sources, but dilute sources will not have the same effect as the highly concentrated PAHs from coal tar sealers.
- Studies have consistently found that traffic-related emissions, not runoff from pavement sealed with refined coal tar-based sealer, are the primary source of all PAHs in the urban environment.
This statement is like quoting studies in 1491 which show most people believe the world is flat. Those studies pre-date more recent studies that calculate that the emissions from curing coal tar sealants exceed the annual exhaust levels from all motor vehicles in the United States. Even the primary USGS coal tar sealer researchers (Mahler and Van Metre) published a paper which cited traffic as a major PAH source before (2000) the coal tar sealer link was found (2003).
- A focus on just refined coal tar-based sealants won’t reduce the amount of PAHs. Even concrete pavements that do not require sealants DO collect PAHs from spills, leaks, abrasion and atmospheric deposition which may be washed into streams during rain events.
This is false statement and poor logic. Just because PAHs can come from all pavements (at dramatically different concentrations) does not mean we shouldn’t be selective in what we use. It’s kind of like saying all food has calories, so what you eat doesn’t really matter.
The US EPA’s own research shows that coal tar sealers have 100 times more PAHs running off than asphalt-based sealers and 1000 times more than unsealed surfaces (see Assessment of Water Quality of Runoff from Sealed Asphalt Surfaces, p.2).
NO HEALTH EFFECTS
- There is no record that PAHs from these pavement sealers have ever caused harm to anyone. Ready-to-use pavement sealers (both refined coal tar and asphalt based) have never been cited for a claim of bad health due to the use of its sealers. Not even the proponents of this legislation can show that it has ever harmed anyone.
This is specifically addressing human health effects. While getting skin burns from coal tar sealers is common (as shown here), the question about longer term exposure is more difficult to definitively answer.- 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 also far higher than that in coal tar sealer.
- Air sampling studies showed refined coal tar based sealers pose no inhalation risk to applicators, manufacturers or the general public.
This statement is referring to a study done by Koppers in 1991 and only reported on in an industry magazine. Recently the USGS performed air sampling above coal tar sealed lots with the following findings:
- Annual PAH emissions from coal tar sealants exceed those from US vehicular emissions. Engine exhaust is usually cited as a major contributor to urban PAH air pollution.
- There was a 50% loss of PAHs from the product in the first 45 days after application via airborne releases.
- The maximum concentration measured after the application of a coal tar sealant was 297,000 ng per cubic meter. The OSHA limit is 200,000 ng per cubic meter.
- Concentrations of one PAH above sealed lots were 10–15 times higher than those measured for global industrial cities, but were not higher than 2 Chinese industrial cities.
- Mean concentration 4 feet above a coal tar sealed surface is 138 ng per cu. meter but the value found that affects the unborn is just 36 ng per cu. meter.
- The IARC (International Agency for Research on Cancer) has not classified refined tar or refined coal tar based sealers as a human carcinogen. Coal tar sealer is NOT and has NEVER been classified as a hazardous material by the EPA.
This is a misleading statement. Ingredients of substances are listed as carcinogens, not the products themselves. One of the substantial ingredients of this product is “coal tar pitch,” a known human carcinogen. Watch this brief video by the USGS before the Springfield City Council in 2010 to learn more: http://www.youtube.com/watch?v=kKKvNihlgMI.
Don’t believe the USGS? How about the National Institutes of Health? Here’s what they say: “Coal tars and coal-tar pitches are known to be human carcinogens based on sufficient evidence of carcinogenicity from studies in humans.” http://ntp.niehs.nih.gov/ntp/roc/twelfth/profiles/CoalTars.pdf
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).”
Even the product information sheet for a coal tar pavement sealer says that the ingredient “coal tar pitch” is a known human carcinogen.
In 60 years of use NO liability or workers comp claims have been made relative to any type of harm caused by this product. Companies, contractors, and homeowners have safely used this product and have never experienced any adverse effects.
This is a false statement as shown above, there are known, adverse effects. The logic here is flawed. There is no comprehensive study of contractors, companies, and homeowners so no one knows for sure. This is called an “argument from ignorance” in logic. Just because you haven’t tested a theory, doesn’t make it false.
ECONOMIC & JOB IMPACT. Many businesses and 1000’s of jobs exist in this state that manufacture, process and apply these sealants. Using inferior alternative sealants also reduces the time in which they can be applied by 20% = 20% less work, 20% less income, 20% more time on unemployment.
The number of jobs seems like a stretch and the 20% reduction appears arbitrary. But coal tar sealers often cure faster in bad weather. Why is that?
Look at USGS’s analysis of volatilization which showed massive airborne discharges of PAHs from freshly applied coal tar sealants in the first 24 hours. In other words, the product works well in low drying conditions because it is causing a toxic PAH plume above it. Is toxic too strong a word for this release? Actually no, since 1 acre of curing coal tar sealant meets a toxic release standard of 1 pound of the most toxic PAH, benzo(a)pyrene in 24 hours. Is extending the sealant season worth this?
The “economic impact” of the use of coal tar sealants is over a billion dollars in the greater Minneapolis area and hundreds of billions nationwide. This cost for an extended sealer season?
AUSTIN, TEXAS BAN – THEN & NOW
The City of Austin, Texas was able to pass an ordinance in November 2005 prohibiting the use and sale of refined coal tar-based sealants. This was done following a less-than scientific study, which failed to include other local sources of PAHs and even disregarding the four former manufactured gas plant (MGP) facilities located at and near the sites of PAH contamination.
A follow-up study in Austin that looked at PAHs in sediments before and 3 years after a municipal ban on the use of refined coal tar-based sealants showed no discernible differences either in the sources or amounts of PAHs in local streams.
QUESTION – If coal tar sealers were the cause of the high PAH levels – why was there no improvement over time?
ANSWER – According to a 2003 article in a local newspaper, the Austin Statesman, “The chemical fingerprint of the contamination at the hillside above Barton Springs pool and in the creek is identical to that of coal gasification wastes…” Coal gasification wastes are found at Manufactured Gas Plant facilities. A subsequent scientific review of the Austin studies, “found that traffic-related emissions, not runoff from pavement sealed with refined coal tar-based sealer, is consistently identified as the primary source of PAHs in the urban environment.”
Strangely this “manufactured gas waste” theory was put to rest back in 2003 in the very same newspaper quoted above (see clip from article below). Add to this that PAH hotspots were found throughout Austin and the additional research by the USGS, State of Minnesota, University of New Hampshire, University of Missouri and others all showing high concentrations of PAHs coming from coal tar sealed lots. Is the author suggesting there are manufactured gas facilities at all of these locations causing high PAH levels?
Concerning the changes in PAH values in Austin, the short answer is that even the industry’s own study stated 2 years after a ban may have been “too soon” to reach a conclusion. This is echoed by the USGS and the City of Austin scientists in their response here.
ALTERNATIVES NOT EFFECTIVE
Asphalt emulsions also contain PAH’s.
Yes but asphalt sealers are 1000 times less, which takes a substance from extremely mutagenic to non-mutagenic in the Ames Test.
Other producers of PAH’s include, motor oil drippings, car exhaust, hot mix asphalt, jet exhaust, tire wear residue, roof shingles, even cigarettes, outdoor grills, volcanos, and forest fires and other outdoor burning, wood burning in home fireplaces.
See the graphic entitled, PAHs in Urban Sources from the USGS above. These sources are generally lower, but significant indoor air PAH pollution can come from certain wood burning fire places.
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.
The days of this exclusive characteristic of coal tar are over. Fuel resistant asphalt and non-coal tar sealers are already on the market today.
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.
This is an opinion that many in the industry do not share. Why did Home Depot and Lowes in 2007 stop using a product nationally when no one asked them to? Because they saw future liability and a suitable substitute.
ENVIRONMENTAL EFFECTS
Banning sealants in the long run will have a much greater impact 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.
Austin’s ban has been in place for more than 8 years with no mass loss of asphalt pavement, and no outcry over the deterioration of asphalt surfaces. To this point, the respected Asphalt Institute, which provides research and technical assistance to pavement managers and designer engineers primarily in the US, recommends against using coal tar sealants over asphalt.
- Place a financial burden on homeowners, businesses, and government, not the mention the lack of “curb appeal” which attracts customers to a freshly sealed and well maintained parking lot.
Today’s asphalt based sealers stay just as black as coal tar sealers and this cleaner product will continue to be an option for Illinois residents if this ban is passed.
Photo credit from the City of Toronto.