4/14/05 Dr Linda Birnbaum: Science Vs Conjecture

Gary Henry, Tittabawassee River Watch April 14, 2005

Dr. Linda Birnbaum’s presentation last night was enlightening to many of 150-200 attendees on both sides of the issue. Overall, the presentation was very useful and we appreciate her efforts to update our community on the latest in dioxin science. However, a portion of the presentation deviated from science and moved into the realm of speculation, adding more questions than answers to an extremely complicated contamination issue.

She confirmed that epidemiological studies of numerous human populations provide the evidence of adverse human effects of dioxin. These effects have been documented in groups (cohorts) ranging from the general population to highly exposed and everywhere in between. Health effects include, but are not limited to cardiovascular disease, diabetes, glucose intolerance, hyperinsulinemaia, hormone disruption, cancer, immune suppression. endometriosis, decreased testosterone, chloracne. Prenatal exposure can lead to developmental problems with the thyroid status, immune status, neurobehavior, cognition, dentition, reproductive effects, altered sex ration and delayed breast development. In other words, the toxicity of dioxin is not in question, it’s a fact based on peer reviewed scientific studies from around the world.

For the most part, Dr. Birnbaum was extremely careful to limit her discussion to her area of expertise as a toxicologist. When asked to provide guidance in areas outside her expertise related to regulation, cleanup, and/or exposure pathways, she did what a good scientist should, cite facts or decline to comment.

However, a major discrepancy developed soon after stating “Dioxin is well absorbed by the GI tract and lungs”. When pressed to comment on whether soil levels of dioxin in our area contribute to our dioxin body burdens, Dr. Birnbaum responded by saying she was not an expert in that field but proceeded to speculate “If I had to put money on it, it’s probably unlikely that your are much more highly exposed than your neighbors who aren’t living in the flood plain.” She followed this statement with the caveat that future studies may prove her wrong.

Unfortunately for the general public, the news media & Dow supporters picked this tidbit of conjecture as the main topic of their coverage, doing the community a further disservice. Perhaps they should give the concept of “Sound Science” something more than lip service.

From the layman’s perspective, ”absorbed by the GI tract and lungs” means that if you breathe or eat it, you absorb it. Flood plain residents are breathing the dust of the contaminated soil and tracking it into our homes 24x7. Has she seen the freshly deposited soil in our yards & vegetation after every flood? Has she driven a lawnmower in the flood plain? Has she seen the dust clouds blowing around after a dry spell? Has she seen our Fish and Wild Game advisories? Why are we told to wear face dust masks when working in our yards, avoid having children play in the soils, and leave clothing worn when working in the yard outside the house? How are we to believe that our soil, flora, and fauna do not contribute to our dioxin body burden beyond that of the general population?

Dr. Birnbaum was unaware of last years MDCH PEI study whose unofficial, preliminary results indicate a large portion of residents tested are accumulating dioxin blood levels much higher than nation averages. In fact, over 60% of the results shared with TRW exceed the 75th percentile and over 60% exceed the top end of the range for people 40-59 years old shown on Dr. Birnbaum’s slide titled “Mean and Range of TEQ’s by Age Group”. Note we are still waiting for the official PEI’s final report. If it should ever be published, these values may change, either up or down.

Dr. Birnbaum stated she is a member of the scientific advisory board for the University of Missouri bioavailabilty study being conducted by Dow. She stated past studies have shown dioxin bioavailablity from soil ranging from 1% to 100% depending upon the makeup of the soil. 100%??? And yet she speculates we do not have any additional exposure from living in the flood plain.

She also stated her concern that the bioavailability study may not be using the right types of soils to represent those found in the Tittabawassee Flood plain. Suggestion: If she is on the advisory board, why not demand the study protocol be adjusted accordingly? Her tone of voice indicated to me that she is dismissing the value of the bioavailabilty study because of it’s design, not the value of the data.

In my opinion, neither the bioavailabiltiy or the U of M Exposure Pathway studies are necessary. They are just another example of paralysis by analysis. We know dioxin is hazardous to humans, that they accumulate in the body, that they take a very long time to dissipate from the body or the soil, the clinical and subclinical effects of dixoin are being detected in the general population of non-contaminated areas, and flood plain residents live every day in close proximity with high levels of dioxin in and about our homes. It does not take a rocket scientist to see that even a little bit extra dioxin in your body is not a good thing in this situation.  The reasonable course of action: take precautions now until the source of the contamination is removed.

So what is the source of the extra dioxin that seems to be prevalent in flood plain resident’s blood? If we get 95% of our dioxin from food like everyone else as Dr. Birnbaum suggests, the remaining 5% could not account for the abnormally high levels in our blood. Where did the rest come from? How did the Tittabawassee fish and floodplain squirrels, turkeys, and deer acquire such elevated dioxin levels? Where did the chicken eggs consumed by river resident’s children acquire the 40 ppt TEQ per egg? The last time I checked, wildlife where not shopping in our local food markets.

How can she speculate that living in areas of highly contaminated soils will have an insignificant effect on our body burdens and also say the Public Health position is: 1) “Current levels in the environment are associated with body burdens in the general population which are at or near the point where effects may be occurring”? and 2) “Continue to reduce sources and Environmental levels” of dioxin.  How can she speculate that living in highly contaminated soils provides an insignificant source of dioxin when the Margin of Exposure for "clearly adverse non-cancer responses" is less than 10?

Public Health should be paramount in this issue in the Tittabawassee watershed.  Speculation and gambling belong in the Mt. Pleasant casino.

Having said all this, we would still like to thank the Lone Tree Council for bringing respected scientist such as Dr. Birnbaum to town. While we did not agree with every thing she said, the vast majority of the information was valuable and the communities understanding of the issues will only improve as they bring in additional speakers in the future.

Click here to download Dr. Birnbaum's power point presentation used at the meeting.

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.