Dioxin is the name given to a group of persistent, very toxic chemicals. The most toxic form of dioxin is 2,3,7,8-tetrachlorodibenzo-p-dioxin or TCDD. TCDD is more commonly recognized as the toxic contaminant found in Agent Orange and at Love Canal, New York and Times Beach, Missouri.
Where does it come from?
Dioxin is not deliberately manufactured. Rather, it is the unintended by-product of industrial processes that use or burn chlorine. The burning chemical at the Koppers wood treatment facility that created dioxins in the 1987 fire was pentachlorophenol (PCP).
Garbage incinerators and medical waste incinerators are two of the largest sources of dioxin identified by the U.S. Environmental Protection Agency. Dioxin released from these and other sources has been found to travel long distances in the atmosphere. Some of the highest levels of dioxin in people have been found in the Arctic, even though there are no sources within hundreds of miles.
According to the EPA, over 96 percent of human exposure occurs through the diet, primarily foods derived from animals. Dioxin in air settles onto soil, water, and plant surfaces. It does not readily break down in the environment and over time accumulates in the grazing animals that eat these plants. People then ingest the dioxin contained in meat, dairy products and eggs. Some exposure also results from eating dioxin-contaminated fish. Dioxin exposure of the general population is most commonly a problem of emissions from many sources that all add up.
Dioxin causes a variety of damage in both animals and humans. Dioxin is a potent cancer-causing agent and is considered to be a “human carcinogen” by the World Health Organization’s International Agency for Research on Cancer and the U.S. Department of Health and Human Services’ National Toxicology Program.
Non-cancer effects: reproductive, developmental, immunological, and endocrine effects in both animals and humans. Animal studies show that dioxin exposure is associated with endometriosis, decreased fertility, inability to carry pregnancies to term, lowered testosterone levels, decreased sperm counts, birth defects, and learning disabilities. In children, dioxin exposure has been associated with IQ deficits, delays in psychomotor and neurological development, and altered behavior including hyperactivity. Studies have found lowered testosterone levels, decreased testis size, and birth defects in offspring of Vietnam veterans exposed to Agent Orange.
Effects on the immune system of the developing organism appear to be among the most sensitive endpoints studied. Animal studies show that dioxin decreased immune response, and increases susceptibility to infectious disease. In human studies, dioxin has been associated with immune system depression and alterations in immune status, leading to increased infections. Dioxin can also disrupt the normal function of hormones—chemical messengers that the body uses for growth and regulation. Dioxin interferes with thyroid levels in infants and adults, alters glucose tolerance, and has been linked to diabetes.
Dioxin Binding with the Ah Receptor
A very brief description of how dioxin is incorporated into cells, with an illustration of the process.
Dioxin Fact Sheet
Shorter version of a Center for Environmental Health & Justice paper describing what dioxin is, how it’s created, and what its health effects are. (Here is a link to the longer, footnoted version.)
If you live in Oroville and want to find out about dioxin contamination in your community, or ask questions/voice concerns, please visit and "Like" our Facebook page. ODEC is made up of Oroville community leaders and citizens working to protect the community from current and future sources of dioxin. The group is always open to working with other local community advocates and has strong ties to many diverse groups in Oroville. We'd love to hear from you, so check out our Facebook page and tell us what's up!
If the resources below do not contain the information you're looking for, please explore our Dioxin Information Directory.
Thanks to Ted Vang for his translation skill!
The 2004 Advisory from the California Department of Public Health has information on reducing health risks from dioxin in backyard chicken eggs.
For more on BEC's testing of Backyard Chicken Eggs and test resuls, click here.
BEC’s involvement with dioxins, beginning in 2010 in Oroville with The California Wellness Foundation grant to test backyard chicken eggs, a graph of the test results.
Our current tests of ash from the Covanta-owned cogeneration plant in south Oroville with a comparison of egg tests.