Diving into Dow and Dioxin

by Seema Jolly on February 24, 2012

After almost two decades of negotiations with the Michigan Department of Environmental Quality, Dow Chemical Company agreed to clean up contaminated residential properties in Midland, Michigan.  Dow is a chemical manufacturer, and for most of the 20th century, polluted the region with dioxin from one of its manufacturing plants.  For residents living in contaminated areas, Dow offered to buy 50 homes that are close to the plant, and will examine up to 1,400 properties for potential contamination.  They will test the soil from neighborhoods to determine if dioxin levels are too high (greater than 250 parts per trillion), and will remediate the soil if necessary.  For many residents in Midland and environmental advocates, this action by Dow has been long awaited.  And for some residents, this action still isn’t enough.

This news surfaced on Thursday, February, 16th just one day before the U.S. Environmental Protection Agency (EPA) released the Reanalysis of Key Issues Related to Dioxin Toxicity and Response to NAS Comments, Volume 1 (essentially, it’s a health assessment for dioxin).  According to Environmental Health News, it took the EPA  “21 years of wrangling over health threats, uncertain science and industry pressure” to release its health assessment to demonstrate how toxic dioxins are.

What are dioxins?  Dioxins are a set of toxic chemical compounds that have similar chemical structures and biological properties.  Dioxin is released into the environment from forest fires, industrial processes (chemical manufacturing, combustion, metal processing, paper mills), burning trash, and incinerating waste.  Once released in the environment, dioxin will stay in the environment for long periods of time because it does not break down easily.  Dioxin can build up in animal tissue when animals consume food that is contaminated.  Consuming animal products (dairy, meat, fish) is the main way humans are exposed to dioxin.  Almost everyone has some level of dioxin in the body.

We know that people are exposed to dioxin but what are the potential health effects?  From the EPA assessment, health effects include: developmental or reproductive effects, skin rashes or discoloration, immune system damage, hormone imbalances, and liver damage.  Dioxin may also be cancerous (however, the current report put out by the EPA was only assessing the non-cancerous health effects.  Volume 2 of the report will include the cancer assessment and will be completed as “expeditiously as possible”).

For people who have been exposed to high levels of dioxin (often because of accidents or large contamination issues), they may develop chloracne, which is a skin disease.  Acne-like lesions may form on the face and upper body.  (Many veterans who served in the Vietnam War developed chloracne from high exposure to Agent Orange, which had dioxin in it).

Despite the fact that the assessment found that health effects occur even at very low levels of dioxin exposure, the EPA asserted that, “generally, over a person’s lifetime, current exposure to dioxins does not pose a significant health risk.”  There is some concern that nursing infants or fetuses would be more sensitive to dioxin exposure but this wasn’t addressed in the assessment.

The EPA finished this health assessment after 21 years of review.  Why is this health assessment a big deal?  Even though no enforceable regulations for dioxin was created, the assessment created an oral reference dose (which is a level that is presumed to have no adverse health risks).  This reference is then used to determine levels that may cause health effects and to create legal limits.  The oral reference dose was determined based on two studies.  In one study, dioxin exposure during childhood was associated with decreased sperm count in men.  The second study found that newborns born to mothers exposed to dioxin had disrupted hormone levels that impact an infant’s growth and development.

Having this health assessment will help serve as an impetus to clean up Superfund sites, regulating emissions from industrial sites, drinking water standards and dietary guidelines in fish.  And, at least for some families in Midland, Michigan, they are receiving long overdue acknowledgement and compensation from Dow for the dioxin pollution that persisted for decades in their community.

Image: Gyre. Smokestack of Greater Detroit Resource Recovery Facility waste-to-energy plant. 03:44, 3 June 2006. From: http://commons.wikimedia.org/wiki/File:Smokestack_in_Detroit.jpg


Michelle Mathas February 25, 2012 at 12:31 am

Hi Seema. That was a great explanation of what is obviously a scary and complicated topic. I was still a little confused by the end about your opinion of the report. Did you think it was much too late, or were you suggesting that made it much more reliable? Did you think it went far enough? People expect to hear your opinion in a blog. My only other comment would be to provide more context around your links, eg in the first paragraph the ‘residents’ link could be extended to ‘residents who still want further action’.

It’s a pedantic point of grammar, but it is really bad to start a sentence with ‘And’, and it will annoy all the grammar nazis out there. I know it is becoming increasingly common, and there are a lot of old grammar rules which are simply not logical in English and should be thrown out the window (eg not splitting an infinitive). In this case however, it is logically incorrect – ie just plain wrong. ‘And’ is a conjunction, or “connecting word”. It cannot connect anything if it is in first position, and it prevents the sentence from being independently meaningful. There is my boring grammar lesson for today :) Thanks for your more interesting science lesson!


Seema Jolly February 28, 2012 at 10:15 am

Hi Michelle,

Thanks for reading and sharing your comments. I’m not sure if you’ve read many of my other pieces, but throughout many of my posts, I’ve often struggled with deciding when to offer my opinion. I’m realizing more and more, people are wanting to hear my take on topics, rather than just “reporting the science.” However, finding that balance between sharing my opinion and not being biased in what I research or how I present it (or owning up to the fact that I am being biased in how I’m presenting data), is taking me time to sort through. Stay tuned for future posts and you’ll get a lot more of my opinion :)

As for my actual opinion on this issue, I think that industry has a lot of power on the government and generally feel that they should be held more accountable for the impact they may have on communities, environment, etc. (with many environmental health issues, it’s hard to prove that pollution from a factory causes health problems. My general take on these issues aligns more with the precautionary principle, or taking more preventive measures and having industry demonstrate that practices are not harmful rather than cleaning up messes after they happen).

Thanks for pointing out the “and” issue. I normally write in a more technical way, but I have been using this blog as a way to reach people in a more conversational way (which, in turn, means that I may not always follow all the grammar rules).

Thanks again for reading!

Angela February 27, 2012 at 9:44 pm

Really liked the post! The only part I found a bit unclear was why the study took 21 years to complete. Can imagine, though, that this was related not just to scientific issues…

Seema Jolly February 28, 2012 at 9:52 am

Hi Angela, I probably should have been more clear about the time it took to produce this report. It was being dragged out because the EPA was getting a lot of pressure from the chemical industry and other groups that would not want more regulation. Which (I’m sure) is part of the reason that the cancer health assessment doesn’t have a set timeline but will be done as “expeditiously as possible.”

Thanks for reading!

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