In fact, a PCTC response to the initial Austin study of runoff into waterways refuted those results, noting that "retesting of this the same body of water?over two years after refined coal tar sealers were banned in Austin showed no discernible difference in either the amount or types of compounds discovered in the initial testing." So PCTC asks, "If coal tar sealers were the cause of the high PAH levels - why was there no improvement over time?"
PCTC says that research "including a 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."
Crude Coal Tar vs. Refined Coal Tar
LeHuray and others say part of the problem with the two Austin studies is their inability or unwillingness to draw a distinction between the crude coal tar by-product of steel manufacturing and the refined tar used to make refined coal tar sealer, which is a selectively distilled product that meets ASTM D 409 specifications for Road Tar (RT-12). Refined tar sealer is not made using crude coal tar as many reports allege.
RT-12, a refined coal tar material, is produced by Koppers, Tangent Rail, Ruetgers, and Coopers Creek and sold to sealer producers as the basis of refined coal tar sealer.
Refined coal tar itself is used in making FDA-approved medications such as shampoos, soaps, ointment treatments for dandruff and psoriasis, and in making acetaminophen. All these products that contain refined coal tar are sold over the counter.
"Neutrogena Corp. (a user of coal tar in dandruff controlling shampoos) published a report that crude tar did not result in any instance of skin cancer when crude tar was applied and kept for 24 hours on large parts of their bodies of 1,924 test subjects," Dubey says. "There has not been any known case of cancer with refined coal tar sealers."
LeHuray adds that it's important to realize that refined coal tar-based products including refined coal tar sealer are not regulated as hazardous waste by the EPA. "The fact that the sealcoating industry uses refined coal tar - and not crude coal tar - has a great deal of impact because of the implication in Austin studies," she says. "If you read those studies crude coal tar is often confused with refined coal tar-based sealer."
Vance agrees. "Crude coal tar and RT-12 are two different materials. Crude coal tar, which is unrefined, has very different physical properties and chemical composition compared to refined coal tar meeting RT-12 specifications," Vance says. "But the material we deal with and the material contractors buy and apply has been chemically processed - it's refined coal tar.
"The product we get from RT-12 suppliers is very different from what distillers get from steel mills as their raw feedstock material. The folks who are doing these studies are trying to lump everything together and that's not accurate. Sealer uses refined coal tar which involves an extra and selective level of processing."
Bill Maclean of The Brewer Company, which produces a refined coal tar-based sealer, adds that the sealcoating industry is committed to producing a quality, long-lasting refined coal tar product that is safe to use. "Everyone we know is trying to do the right thing," Maclean says. "No one is looking to produce a product that harms people or the environment.
"It is unfortunate that the research so far is one sided and subjective and that contradictory research is lagging. If you're going to have a debate like this you need to not cloud the issue," Maclean says. "We were probably naïve to think we didn't need research to defend ourselves and we are certainly behind the curve. But we're well along the way to changing that."