Dioxins are a group of highly toxic chemical compounds that are harmful to health. They can cause problems with reproduction, development, and the immune system. They can also disrupt hormones and lead to cancer.

Dioxins, which are known as persistent environmental pollutants (POPs), can remain in the environment for many years. They are everywhere around us.

Some countries are trying to reduce the production of dioxins in industry. In the United States, people do not produce or use dioxins commercially, but they may be a byproduct of other processes.

The Environmental Protection Agency (EPA) and other bodies have reduced the production of dioxin levels in the U.S. by 90% since 1987.

However, it is not easy to eliminate dioxins. They can come from natural sources such as volcanoes and forest fires, they can cross borders, and they do not break down quickly, so they stay in the environment for a long time.

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Dioxins are toxic chemicals that are present almost everywhere in the world. Pure dioxin looks like white, crystalline needles. In the environment, however, it is present in microscopic particles that people cannot see.

Sources include:

  • burning processes, such as backyard burning and commercial or municipal waste incineration
  • the use of fuels, such as wood, coal, or oil
  • natural phenomena, such as volcanic activity and forest fires
  • industrial processes, such as chlorine bleaching of paper pulp and smelting
  • the production of some herbicides and pesticides
  • the dismantling and recycling of electronic products
  • cigarette smoking

Dioxins can travel long distances in the air or water. When they settle in soil and sediment, they can stay there for a long time because they break down slowly.

Fish and other organisms can swallow or absorb dioxins so that they enter the food chain. Animals tend to have higher concentrations than plants, water, soil, or sediments. In animals, dioxins tend to accumulate in fat.

Exposure to dioxins can come through:

  • consuming food, especially animal fats, where dioxins have accumulated
  • drinking water where dioxins have settled or where there is contamination from industries
  • breathing in vapor or air that contains trace amounts
  • accidentally ingesting soil that contains dioxins
  • absorbing dioxins through skin contact with air, soil, or water

Dioxins can stay in the body for a long time. It may take 7–11 years for a dioxin’s toxicity to reduce to half its original level.

Learn more about how air pollution affects people’s health.

Major contamination

According to the World Health Organization (WHO), most reports of dioxin contamination occur in industrialized nations where there is a system of monitoring and reporting. In other places, high dioxin levels may go unreported.

There have been some cases of major contamination. Here are some examples:

  • In 2008, contaminated animal feed led to pork products from Ireland containing more than 200 times the permitted levels of dioxins.
  • In 1999, the illegal disposal of industrial oil led to the contamination of animal feed and animal-based food products from Belgium and some other countries.
  • In 1976, an industrial accident produced a cloud of toxic chemicals, including dioxins, which affected thousands of people in Italy.

In 2004, Viktor Yushchenko, the President of Ukraine, was intentionally poisoned with dioxins.

When dioxins enter an animal in the food chain, they accumulate in fat. More than 90% of human exposure to dioxins comes through food — primarily animal products, such as dairy, meat, fish, and shellfish.

Older research reported traces of dioxins in the following foods:

  • freshwater fish
  • butter
  • cheese
  • hot dogs and bologna
  • human milk (from breastfeeding)
  • ice cream
  • eggs
  • ocean fish
  • beef, chicken, and pork

Of these, freshwater fish contained by far the highest amounts.

To reduce the risk of exposure from food, the WHO recommends:

  • choosing lean meats and fish
  • cutting off fat when preparing meat
  • varying the diet to reduce the risk of exposure to a high concentration in a specific food
  • favoring fruits, vegetables, and whole grains over meat and fish where possible

When fishing for food, the National Institute of Environmental Health Sciences (NIEHS) advises people to check first on current dioxin levels with the local authority.

Some people have raised concerns about dioxins in menstrual and sanitary products, especially tampons.

Before the late 1990s, manufacturers used chlorine for bleaching in tampon production, and dioxin levels were higher. They no longer use chlorine bleaching, and, as a result, dioxin levels in these products have fallen.

However, an article that the NIEHS published in 2014 notes that there is not enough research to show how the chemicals in tampons can affect a person’s health.

In the past, some people have also claimed that plastic water bottles contain dioxins, but experts say that this is not true.

They warn, however, that water bottles contain bisphenol A (BPA) phthalates, which can lead to hormonal and endocrine problems and possibly reproductive issues, as well.

Is it better to drink bottled or tap water?

There are several hundred dioxins, which belong to three closely related families.

These are:

  • chlorinated dibenzo-p-dioxins (CDDs)
  • polychlorinated dibenzofurans (PCDFs)
  • some polychlorinated biphenyls (PCBs)

People do not create CDDs and PCDFs intentionally. These occur as byproducts of human activities or because of natural processes.

PCBs are manufactured products, but manufacturers no longer produce them in the U.S.

Sometimes, people also use the term dioxin to refer to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), one of the most toxic dioxins. Experts have linked TCDD to the herbicide Agent Orange, which people used during the Vietnam War to strip the leaves from trees.

What is the link between Agent Orange and chronic lymphocytic leukemia?

Scientists have linked exposure to dioxins to various adverse effects, including:

  • cancer
  • congenital disabilities
  • pregnancy loss
  • decreased fertility
  • reduced sperm counts and low testosterone levels
  • endometriosis
  • diabetes
  • learning disabilities
  • immune system suppression
  • lung problems
  • skin disorders

Dioxins can pass from a person to a fetus during pregnancy and to a baby through breastfeeding. If this occurs, it could lead to neurodevelopmental problems.

The risks depend on a variety of factors, including:

  • the level of exposure
  • when the exposure occurred
  • the length and frequency of exposure

According to the WHO, however, the background exposure that most people experience in daily life is unlikely to be hazardous.

Although it rarely occurs, high levels of exposure over a short time can sometimes lead to chloracne. This severe skin disease produces acne-like lesions, mainly on the face and upper body. Chloracne can happen if there is an accident or a significant contamination event.

Other possible effects of exposure include:

Dioxin testing for humans is not routinely available, but some measures can help reduce the risk of exposure. They include:

  • avoiding fatty meats or cutting the fat off meat before using
  • checking dioxin levels in local waters before fishing for food
  • following best practices when carrying out backyard burning

The EPA notes that burning waste materials in the backyard can create levels of dioxins higher than those from industrial incinerators. Backyard burning releases pollutants at ground level, where they are more likely to affect people and enter the food chain.

How can you know if tilapia and other fish are safe to eat?

Dioxins are poisonous substances resulting from human and natural processes, including manufacturing, volcanic activity, and backyard burning. Manufacturers can no longer produce dioxins in the U.S., but these substances are present in the environment and possibly in the food chain.

Exposure to dioxins increases the risk of cancer and some developmental and reproductive problems. Ways of avoiding dioxin exposure include trimming any fat from meats, consuming a varied diet, and avoiding backyard burning.