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