Results of the First Federal Study on Coal Tar Exposure

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Results of the First Federal Study on Coal Tar Exposure. For the very first time, the federal government has released a study on the harmful effects of coal tar. The National Institutes of Occupational Safety and Health (NIOSH) conducted a 6-year study of people who work in and around coal tar sealers and products, particularly hose men and truck drivers. NIOSH is a part of the U.S. Department of Health and Human Services and The Centers for Disease Control and Prevention (CDC). Coal tar sealers have been used in the U.S. since the 1940’s despite known carcinogenic effects. This is the first study of its kind to actually measure the effects of coal tar on workers and the load of carcinogenic compounds in their system after a shift working with these substances. What they found is shocking!

The Study Parameters

The study followed twenty-one workers on crews from three separate companies using coal tar sealers. The participants had different levels of protection from Tyvek to none at all to wearing the same clothes during the week. They studied skin exposure, air concentrations and urine concentrations of various coal tar chemicals. Urine was tested before and after each shift. Chemicals from coal tar sealers called polycyclic aromatic hydrocarbons (PAHs) can enter the body through the skin, breathing it in or eating with residue on the hands. Many of these PAHs can be measured in urine tests.

The Results of the Study

What did the researchers find out about coal tar sealers and chemicals? Here’s a quick synopsis:
  • Coal tar chemicals were found in ALL workers in the crew and were ALWAYS higher after a shift than before.
  • By the end of each work week, 9 out of 10 shift-end samples “greatly” exceeded the level where the workers should expect negative health effects and “genotoxicity” (gene mutations caused by exposure to toxins).
  • Four of the PAH chemicals found in the urine samples don’t even have individual safe levels of exposure data “because they have been observed to be carcinogenic in animal studies.”
  • Urinary levels of one of the PAH chemicals was over 300 times higher than is observed in the general population.
  • The exposure levels observed were “substantially” greater than what has been seen with asphalt workers previously.
  • Hose men or applicators had higher concentrations of airborne PAH and skin exposure than non-applicators.
  • The exposure could not be explained by any other nearby chemical source.

While considering these results, also consider that children are 30 TIMES more susceptible to the dangers of coal tar and other high PAH sealers than adults. Also consider that the exposure routes included breathing in the chemicals as well as skin contact and residue on the hands when eating (ingestion).

The study did not address whether personal protection equipment or PPE would be sufficient to protect workers. The most effective way to address carcinogenic chemicals in the workplace (even if the workplace is outside) is elimination of those chemicals. There IS a way to completely eliminate exposure to coal tar and coal tar toxins. It’s called Pitch Black Asphalt Emulsion and it contains 0.00% of the harmful PAHs found in coal tar products. It’s safe and environmentally friendly. This study makes it clear that coal tar is a serious danger not only for workers but for others near work sites that could be exposed by proximity. Finally, we have a study from the federal government showing the true dangers of coal tar products and sealers. The time to move to a cleaner and greener solution is now!

Note: A copy of this 32-page study can be purchased at