'Uncertainty' needs to be addressed in dioxin debate

Warren Crummett, Midland Daily News 10/16/2005

The spring of 1976 brought a session of the "Environmental Protection Agency's Science Advisory Board on Analysis & Testing". It's chairman, Prof. Frederick D. Rossini, a leading chemist of the 20th century, had a profound message for us: "Unless we can really measure it, we know nothing about it", he declared and continued: "If we do measure it there is associated with the measurement a specified range of uncertainty". "This " uncertainty" must itself be measured before we use the data to state hypotheses and make important decisions about the environment" His remarks inspired considerable scientific action!

For example, a few months later the "Dow Dioxin School" (named by European scientists) announced the discovery of "dioxin" in fish in the local river. The measurement used methodology initiated and partly developed by the cooperative effort of university (Harvard, Wright State, Univ. of Nebraska; government (EPA, FDA) and industry (Dow) laboratories as members of EPA's "Dioxin Implementation Plan." At Dow the methodology had been so carefully refined by the chemists, Terry Nestrick and Les Lamparski, that "dioxin" was determined in fish in the parts per trillion concentration range with less "uncertainty" at these very low concentrations than previously thought possible.

In 1980, as chairman of the American Chemical Society "Committee on Environmental Improvement," I was honored to publish a report on "Guidelines for Data Aquisition and Data Quality Evaluation in Environmental Chemistry" which assured that "uncertainty" be measured and understood. This report was approved by both the ACS and the EPA. Thus the concentration of "dioxin" could now be measured by laboratories complying with the "guidelines" (later called "principles" by EPA). The process is expensive and some laboratories are reluctant to "bother."

On Sept. 1, 2005, during the 230th American Chemical Society National Meeting in Washington, D.C., the Division of Analytical Chemistry sponsored a symposium titled: "Quantification of Measurement Uncertainty". The titles of the papers presented suggest that chemists are seeking ways to estimate "uncertainty," thus avoiding the tedium and rigor of "sound scientific methods." Evaluating the appropriateness of such techniques will be very difficult but the papers have not yet been made available to me.

At this same conference, a symposium sponsored by the "Division of Chemical Toxicology" and the "Division ef Chemistry and the Law" titled "Where Toxicology Meets the Law -- Focus on Dioxin" was held. The most significant paper appears to be "Dioxin risks in perspective." This cannot be done unless "uncertainty" is properly measured and understood.

The problem of "uncertainty" is especially acute in epidemiology studies and, without true measurements of "uncertainty," reliable statements about "risk" cannot be made. Thus Dr. Bimbaum of EPA correctly uses verbs like "may possibly" to claim a possible"concern" but not "fact."

Unless the problem of "uncertainty" is addressed (and the results completely reported) the results on samples from the Saginaw Valley will be meaningless, or, at best, suspect.

Since "uncertainty" data is almost never made public, we must rely on the Scientist Advisory Boards of the various studies for assurance. "Sound science demands the highest integrity! It can never consist of "a quick fix."

Warren Crummett is a retired research scientist at The Dow Chemical Co.

©Midland Daily News 2005

Reader Opinions:

David Linhardt Oct, 16 2005 I have known Warren for a number of years and, even with the passage of time, I still have trouble understanding the point that he oftens tries to make while using far too many words.

Warren's plea to remember that dioxin measurements have some uncertainty might have been clearer if he had used an example. Allow me to make one. Measurements of dioxin in the floodplain of the river have found levels as high as 20,000 ppt. If we assume that there is an uncertainty of plus or minus 10%, the actual level may have been as high as 22,000 ppt or as low as 18,000 ppt. Even with some uncertainty as to the actual level, the lowest level of 18,000 ppt is significantly higher than the 90 ppt recognized as a reasonably safe level.

Warren may have a valid point at a level of 5 ppt, but at the levels being found in the river and in the community, his point is somewhat moot.
 

For additional articles like this one, go to the Tittabawassee River Watch web site www.trwnews.net for complete coverage of the Tittabawassee River Dow Chemical dioxin contamination saga. . The Newspaper / Media page of our site contains an extensive archive of media articles dating back to January 2002. The source organization's web site link is listed to the right of the article, visit often for other news in our area. The Newspaper / Media page may be accessed by scrolling down to the bottom of the CONTENTS section and clicking on the Newspaper/Media link.