Silica Science – Junk Science is Not Limited to The Courts

“Clowns to the left of me; Jokers to the right; here I am, stuck in the middle with you.”


David Michaels, head of OSHA, back in October, was testifying at a House congressional oversight hearing, “Workplace Safety: Ensuring a Responsible Regulatory Environment.” The Congressmen were inquiring into OSHA’s enforcement and regulatory initiatives on several fronts, including silica exposures.

This is the same David Michaels who used to be a hired expert witness for plaintiffs in toxic tort cases. SeeDavid Michaels’ Public Relations Problem,” (Dec. 2, 2011).

Not surprisingly, when the questioning turned to silica, Michaels played the cancer card:  crystalline silica is a “known” human carcinogen.

Republican congressman Larry Bucshon (R-IN), a surgeon when he is not holding forth in Congress, found the talk of cancer to be provocative.  Buchson scolded Michaels:

“I don’t like it when people use buzz words that try to get people’s attention, and cancer is one of those.”

* * * * *

“…I’m a thoracic surgeon, so I want to focus a little bit on what you said earlier as it relates to silica dust. I’m curious about your comment about silica-dust related lung cancer, because I’ve been a thoracic surgeon for 15 years and I’ve done a lot of lung cancer surgery, and I haven’t seen one patient that’s got it from silica dust.”

A fascinating exchange for several reasons.

First, we could expect Michaels to play the cancer card, just as he has in his role as plaintiffs’ expert witness.  As we will see, his cancer evidence is not far fetched, although it is also not particularly convincing.

Second, the junk science from Congressman Buchson is distressing.  As a physician, he should know better that his experience in surgery has no relevance at all to the question whether crystalline silica can cause lung cancer.

Back in 1996, a working group of the World Health Organization’s International Agency for Research on Cancer (IARC) voted to reclassify crystalline silica, the most ubiquitous mineral on the face of Planet Earth, a known human carcinogen.  Michaels recited this “evidence,” but he failed to mention that the evidence was conflicting, as were the votes of the working group. The response of the scientific community to the IARC pronouncement was highly critical.  See Patrick A. Hessel, John F. Gamble, J. Bernard L. Gee, Graham Gibbs, Francis H.Y. Green, W. Keith C. Morgan, and Brooke T. Mossman, “Silica, Silicosis, and Lung Cancer: A Response to a Recent Working Group Report,” 42 J. Occup. Envt’l Med. 704 (2000).

The vote of the working group was very close; indeed, the swing of a single vote would have changed the outcome. One of the working group members later wrote:

“Some equally expert panel of scientists presented with the same information on another occasion could of course have reached a different verdict. The evidence was conflicting and difficult to assess and such judgments are essentially subjective.”

Corbett McDonald & Nicola Cherry, “Crystalline Silica and Lung Cancer:  The Problem of Conflicting Evidence,” 8 Indoor Built Environment 121, 121 (1999).  Remarkably, this panel member explained his decision to vote for reclassification as follows:

“The basic problem was that the evidence for carcinogenicity was conflicting – generally absent in situations of high and widespread exposure and strong only in a few rather special occupations.  The advice by the IARC to consider hazard rather than risk did much to resolve the difficulty.”

Id. at 125.  I suspect that the evidence for a difference in meaning between “hazard” and “risk” is even more tenuous and conflicting than the evidence in favor of carcinogenicity.

IARC classifications, however, take on a life of their own.  They are an invitation to stop thinking, and to stop analyzing the evidence.  Federal bureaucrats and staff scientists love them for exactly this reason:  they can hide behind the authority of the WHO without having to work on reviewing the evidence, or updating their judgment when new studies come out.

It should not be surprising, therefore, that the National Institutes of Health’s National Toxicology Program (NTP), working off the WHO decision, recognized crystalline silica as a human carcinogen. Other groups followed in lock step.  Other agencies and medical groups followed.

What you will not hear from Michaels or his followers is that when the National Institute for Occupational Safety and Health conducted the largest mortality study on the issue, it found a decreased lung cancer risk among men who actually had sufficient silica exposure to develop silicosis. See Geoffrey Calvert, et al., “Occupational silica exposure and risk of various diseases:  an analysis using death certificates from 27 states of the United States,” 60 Occup. Envt’l Med. 122 (2003).  Cf. “Congressman tells OSHA chief not to use “buzz” words like cancer.” (Oct. 10, 2011).

To give the devil his due, at least Michaels had “some” evidence to support his pronouncement, even if the evidence was incomplete and contradicted by other important evidence.  Congressman Bucshon’s recitation of his experience as a surgeon was completely off the mark.  His staffers obviously failed him in their research, and Bucshon’s reliance upon his own anecdotal experience was quite inappropriate to rebut the dubious judgment of the OSHA Administrator.

Some people might describe the exchange between Bucshon and Michaels as resembling two monkeys playing chess.  I think of it as exemplifying the scientific illiteracy in all three branches of our government.

David Michaels’ Public Relations Problem
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