Dioxin Overview

The term "dioxin" is commonly used to refer to a family of chemicals that share chemical structures and characteristics. Polychlorinated dibenzo dioxins (PCDDs) and polychlorinated dibenzo furans (PCDFs) are trace  unwanted by-products of industrial and natural processes, often involving combustion. Non-industrial sources include backyard burning of household waste, and forest/brush fires.  Of the 210 dioxin and furan compounds, 17 are the focus of regulatory action. For the purposes of this web site, the term "dioxin" includes both dioxins and furans.

Twelve of the polychlorinated biphenyls (PCBs) display a related chemical structure and share some of the biological properties of dioxins.  PCBs were manufactured commercially until 1977. However, Dow did not commercially manufacture PCBs.

Dioxin in the Environment

Unless it is exposed to sunlight, dioxin decomposes very slowly in the environment.  It is not fully understood how dioxins get into the food supply.  For example, dioxin deposited on plants and in soil could be consumed by animals and aquatic organisms and may accumulate in their fatty tissue. People are exposed to dioxin  through consumption of  animal products such as meat, dairy and fish.  Levels detected in humans and the environment peaked in the 1970s and have been declining ever since.

Emissions Reduction
According to the U.S. Environmental Protection Agency, dioxin and furan emissions to the environment in the U.S. have been reduced by approximately 90 percent between 1987 and 2000, the last year for which data exists. Globally, emissions also continue to decline.  While it is important for industry to continue to strive for further reductions, other, more significant emission sources need to be addressed as well to have any meaningful overall reduction in the environment.  Today, the uncontrolled burning of residential waste and accidental fires at landfills are estimated to be among the largest sources of dioxin and furan emissions around the world.

Appropriate Action
Dow supports the reduction of dioxin and furan emissions and actively promotes improvements and solutions across the chemical industry.  Dow believes actions taken to lessen human exposure should be specific to a particular situation, and decisions should be based on science and risk principles and the realistic probability for exposure.  We seek science- and risk-based solutions that protect human health, the environment, and contribute to the well-being of local communities.

Additional Information
Dioxins and Furans Defined

Dow's Interest

Dow is associated with dioxin due to the company's historical operations, including:
  • the manufacture of trichlorophenol, pentachlorophenol, certain herbicides and certain other chlorinated products; and
  • studies of Dow employees, and the work of its scientists in understanding the potential health effects of dioxin, and development of analytical techniques to quantify the presence of dioxin and dioxin-like materials which are found at extremely small concentrations.

Although Dow has reduced its emissions of dioxins and furans to air and water by more than 80% since 1995, issues related to current manufacturing processes and historical dioxin and furan emissions continue to be managed by Dow today.

Agent Orange was applied by the military during the Vietnam War to protect U.S. and allied soldiers.  Agent Orange litigation is focused on trace amounts of dioxin in the product. The government contractors, including Dow, manufactured the product according to government mandates.

For more information, please see Current Regional Issues.

Additional Information

Dioxins and Furans Defined

Related links
Agent Orange

Dow's Position

Dow is committed to responsibly manufacturing and supplying the building blocks of chemistry that help produce essential products to make our lives safer, healthier and more convenient. We acknowledge dioxins and furans are unwanted by-products of chlorine chemistry and have undertaken considerable efforts to reduce dioxin and furan emissions to the environment.

Health Effects

Scientific studies of people who have had exposures to dioxins hundreds or even thousands of times higher than background levels (as documented by blood measurements) have not consistently demonstrated any adverse health effects other than chloracne in some cases. Temporary liver and other biochemical changes have been reported in some studies.  These temporary changes have not led to long-term adverse health impacts in people.

Since 1967, Dow scientists have conducted numerous studies among its employees around the world who have been exposed to a variety of chemicals, including certain dioxin and dioxin-like chemicals.  Results of all studies demonstrate the same conclusion — that Dow employees who were exposed to high levels of dioxin in an industry setting generally do not have a higher risk of disease, with the exception of chloracne¹, which occurred in employees who experienced very high exposure levels.

Reducing Emissions

Dow has reduced dioxin and furan emissions and actively promotes technology improvements across the chemical industry.  Dow believes actions taken to lessen potential human exposure should be specific to a particular situation.  Decisions should be based on science and risk principles and the realistic probability for exposure and absorption into the body.  We seek science and risk-based solutions that protect human health, the environment, and contribute to the well-being of local communities. For additional information, see Dow’s Progress on Reducing Emissions.

Managing Issues Related to Historical Operations

Many of the legacy issues surrounding dioxins and furans relate to discontinued products, production processes and waste handling practices. We are managing those issues related to our historical operations. For additional information, see Current Regional Issues.

Regulatory Action
Dow supports a consistent, coordinated regulatory environment for substances at global, national and regional levels to complement voluntary industry efforts.

  • U.S. Environmental Protection Agency Reassessment
  • The National Academy of Sciences (NAS) panel reviewed the U.S. Environmental Protection Agency's (EPA's) draft dioxin reassessment and issued its report in July 2006. Overall, the NAS panel was critical of EPA’s approach and recommended EPA make a number of significant changes to the draft dioxin reassessment. In response, EPA revised the draft assessment, for review by its Science Advisory Board (SAB). The report issued by the SAB at the end of August 2011 was critical of EPA's treatment of cancer endpoints. Specifically, the SAB was critical of EPA's refusal to do a non-linear dose-response assessment for cancer endpoints or to attempt to bound the uncertainty associated with its cancer risk models. EPA anticipates issuing its final dioxin reassessment for non-cancer endpoints in January 2012, but has not set a date for the release of the dioxin reassessment for cancer endpoints.
  • Stockholm POPs Treaty
  • Dioxins are one of the 21 chemicals or chemical categories currently covered under the Stockholm POPs (Persistent Organic Pollutants) treaty (12 original and 9 added in May 2009).  Dow actively supports this international agreement.  For additional information, see Stockholm Treaty/Persistent Organic Pollutants.