Dioxin
A serious concern for Maine
Exposure | Concerns | What's been done | What's happening now
Dioxin is a serious concern for Maine and the world. It is found everywhere, and we all have some in our bodies. While there is scientific debate about exactly how much of a health hazard it poses, many health scientists agree that it is significant, and that dioxin reduction and elimination is essential to protect human health.
What is dioxin? Where does it come from?
When we talk about "dioxin", we're really talking about a family of chemical compounds. These are formed through combustion, chlorine bleaching and manufacturing processes. The critical ingredients are heat and chlorine.
Since chlorine is commonly found in our environment, natural events such as a volcano or a forest fire can lead to dioxin formation. However the greatest source of dioxin is human activity.
Dioxin is created by individual activity like backyard burning of trash and by wood stoves. Industrial processes, like using chlorine to bleach paper or burning municipal trash in an incinerator, produce dioxin as well.
How are we exposed to dioxin?
Particles released by combustion eventually fall to earth. The dioxin they contain clings to dirt and organic matter, and is only slowly broken down. Through a process called "bioaccumulation", very small amounts of dioxin can be taken up by plants; animals that eat those plants accumulate dioxin in their fatty tissues. A similar bioaccumulation process occurs in waters when dioxin builds up in the fatty tissue of fish. At the federal level, there is an effort underway to better understand how we are exposed to dioxin once it is created.
Nearly all of the dioxin that we take into our bodies comes from eating meat, poultry and dairy products in the regular food supply. One reason that Maine has a fish consumption advisory is to limit the amount of dioxin we get from fish in our own rivers.
What concerns us about dioxin?
- Its persistence:
Unlike many compounds, dioxin does not quickly break down and can exist for many years after it is formed.
- Its health impacts:
At extremely low levels, dioxin can alter the way cells grow and develop. Scientists agree that one form of dioxin causes cancer in humans; some chemical forms of dioxin are considered likely to cause cancer. Other known human health effects range from a severe acne-like condition to reproductive problems and birth defects.
What has been done to limit our exposure to dioxin?
- Efforts to reduce air pollutants have cut dioxin emissions nationally by an estimated 80% between 1987 and 1995. These efforts continue.
- In Maine, dioxin concentrations as measured in the fish in our rivers has declined significantly since 1990 (see the most recent Dioxin Monitoring Program Report)--more than 75% in the Penobscot River alone. Initiatives contributing to this continuing decline include:
What's happening now to better understand and deal with dioxin?
- At the federal level, a scientific advisory has completed its review of a comprehensive reassessment of dioxin and its effect on human health. Once finalized, it will provide new insights into the dangers posed by dioxin and how best to address them.
- Maine's Department of Environmental Protection has undertaken to inventory the sources of dioxin in our state in order to be in a position to make the best use of EPA's reassessment. The data and models tell us that about 15.5 grams of dioxin are emitted into our air each year. Nearly half of that comes from commonplace activities, such as back yard burning of trash and wood stoves. Wood fired commercial boilers, municipal waste incinerators and medical waste incinerators make up most of the rest. Almost 100 percent of the solid waste materials with dioxin (e.g., ash, paper mill sludge) are landfilled, effectively preventing the estimated 35.4 grams of dioxin in them from escaping to the environment. Finally, of the 2.5 grams estimated to be discharged directly in wastewater, most is believed to be from pulp and paper mill discharges.
The discouraging news is the pervasive dioxin already present in our environment is not going away soon. However, the good news is that the amount of new dioxin being created is steadily decreasing, and dioxin concentrations in our fish, in our bodies and in our environment are by all measures decreasing. With diligent efforts to keep reducing sources of new dioxin and the passage of time, this potent toxin will become less of a health threat, and more of a cautionary legacy of the industrial revolution.
