The Myth of “Controversial” Coal Tar Sealant Science

In the recent USA TODAY article about  pavement sealcoats, the coal tar industry labeled  research conducted by USGS and others as “controversial science.”  It is a retread of an old industry position, but I thought it might be helpful for a little further examination of this claim.

This is only controversial in the spins of those who make this stuff. Here’s the tally:

  • Number of research groups finding problems with coal tar sealants without funding from a product manufacturer: 15 (100%)
  • Number of industry-funded research groups saying no problems with (or uncertain about) coal tar sealants: 2

Leaders from the USGS, and Minnesota Pollution Control Agency (MPCA) weighed in on the veracity of their work. “We have done rigorous, scientific surveys and analyses showing coal tar sealants are a major sources of PAHs in the environment,” says Dr. Judy Crane, a water quality scientist at MPCA.

Studies with Missouri State University and the University of New Hampshire were also mentioned in the USA TODAY article, but research has also been done at the ATSDR (Agency for Toxic Substances and Disease Registry), Southern Illinois University, the DuPage River/Salt Creek Working Group (suburban Chicago), the City of Austin, Texas, the University of Toronto, Texas State University, Wisconsin Department of Natural Resources, New York Academy of Sciences, the University of Illinois, Tubingen University and this little research outfit called the Environmental Protection Agency. Researchers at all of these institutions find one common thread: there is a pollutant problem with coal tar sealants.

It was also supported by the The National Research Council of the National Academies, with nearly 150 years of Congressional authorization on science, medicine and engineering. Their byline is “Advisors to the Nation on Science, Engineering and Medicine.”

Even a study by the head of the lab at Mobil Oil found coal tar sealants to be toxic! Hardly from a group of activists.

Let’s add to this what the Chicago Tribune found was a pattern of the industry overstating the findings of their own research.

Even the typically-reticent USGS told the Chicago Tribune the following:

She (Dr. Barbara Mahler) said that while the industry studies conclude uncertain findings, they tell their audiences something different. “They make very misleading statements, and if you don’t know any better it can all sound convincing,” Mahler said in an interview. “The conclusions of their studies are they can’t reach any conclusions. But you wouldn’t know that from what they say to the public.”

Still sound controversial?