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Dioxin in Butte County

Dioxin Information Directory:

What Is Dioxin?

Koppers Superfund Site in Oroville

Resources on Dioxin

Covanta's Cogeneration Incinerator in Oroville (POPI)

Health Effects of Dioxin        

Map of BEC's testing results of backyard chicken eggs

What is Dioxin?

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.

How can I be exposed?

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.

Health Effects of Dioxin

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.)

Oroville Dioxin Education Committee (ODEC) Facebook Page

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!

BEC's History with Dioxin:

BEC’s work on dioxin began several years ago through two multi-year grants from The California Wellness Foundation, which enabled us to follow-up on a study conducted by the State of California's Environmental Health Investigations Bureau after a 1987 fire at the Koppers wood treatment facility (a Superfund site). Our research and successful public outreach on this issue caught the attention of the Butte County District Attorney’s office, who requested that BEC investigate the potential human health impacts of pollution from the Pacific Oroville Power Industries (POPI) cogeneration incinerator.
You may recall a 2008 story on the cancer cluster reported in Oroville but because of the time lag, you may not connect this story with the 1987 fire at the Koppers wood treatment facility in Oroville.  The fire released a toxic cloud of dioxins that settled on south Oroville. In 2001, the California Dept. of Public Health (CDPH) tested backyard chicken eggs and found that dioxin levels had not gone down.  February 2012, the Butte Environmental Council tested another round of eggs and found there were still dangerously high levels of dioxin.
You might have also heard recently that dioxins continue to be spread around Butte County. Testing of an ash pile in north Chico from the Pacific Oroville Power Industries (POPI) biomass incinerator revealed illegally high levels of TCDD (the most toxic form of dioxin); there are several such ash piles scattered throughout Butte County.

Overview Information

If the resources below do not contain the information you're looking for, please explore our Dioxin Information Directory. 

Read the March 2014 Butte County Public Health Dioxin Summary

New: 2004 Dioxin/Backyard Chicken Public Health Advisory, Hmong Translation


Thanks to Ted Vang for his translation skills!


The 2004 Advisory from the California Department of Public Health has information on reducing health risks from dioxin in backyard chicken eggs.

Press Release: BEC, Oroville Community Group launch dioxin awareness campaign

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.