What is dioxin?
Dioxins are a group of highly toxic chemical substances. They are mainly formed during burning: waste incineration, the metal industry, bleaching paper with chlorine and open fires. They hardly break down in the environment. In the bodies of animals and humans they build up in fat. It takes 7 to 11 years for half of it to disappear again.
At a high dose, dioxin causes a skin disease (chloracne) and damages the liver. A low dose over a long period can harm the immune system. The same applies to the development of the nervous system, to hormones and to fertility. The most toxic dioxin, TCDD, is classified as carcinogenic to humans by the International Agency for Research on Cancer (IARC).
Dioxin in the food chain
More than 90% of the dioxin we take in comes from our food. Mainly from meat, dairy, fish and shellfish. Dioxin settles on meadows and fields. Animals take it in with grass, soil and feed. It builds up in their fat and so ends up in meat, milk and eggs. Between people, dioxin is passed on mainly during pregnancy and through breastfeeding. Through manure it returns to the environment.
A second route is contaminated animal feed. In 1998 dioxin was found in citrus pulp from Brazil, a raw material for animal feed. In later crises it entered the feed through contaminated fat, as in Belgium (1999) and Germany (2010-2011).
In 2026 the European Food Safety Authority (EFSA) sharply lowered the tolerable weekly intake: 0.6 picograms per kilo of body weight. That is more than three times lower than in 2018. According to EFSA, Europeans in all age groups take in more than that on average. The most sensitive effect is lower sperm production in boys whose mothers were exposed to dioxin.
Free-range and backyard chickens
Chickens that live outdoors peck at the soil. If the soil contains dioxin, so do their eggs. In 2006 researchers at Wageningen University & Research (WUR) in the Netherlands showed that in parts of Europe the soil is often too polluted to produce free-range eggs that meet the European standard. In 2014 Dutch researchers (RIKILT and RIVM) sometimes found high levels of dioxin and PCBs in eggs from private chicken keepers in the Netherlands. PFAS adds to this: in many places the Dutch health authorities (RIVM and GGD) advise against eating eggs from backyard chickens.
Cattle on river floodplains
The soil of the floodplains along the large Dutch rivers contains old pollution. Cattle that graze there all year round for nature management take in dioxin and PCBs, mainly through the soil and through silt on the grass. In 2020 the Netherlands Food and Consumer Product Safety Authority (NVWA) found levels in this meat that were too high. According to BuRO, the NVWA's risk assessment office, eating this meat regularly can pose a health risk (2022). So "nature meat" is not automatically clean either.
Contamination in the past
The Netherlands: Philips-Duphar and the toxic dumps
From 1955 to 1963 Philips-Duphar made raw materials for weed killers in a factory in Amsterdam. In 1963 a reactor vessel exploded there. A cloud of dioxin was released. The factory hall was so contaminated that it was demolished, encased in concrete and dumped at sea. The factory's waste was dumped on the Diemerzeedijk and in the Volgermeerpolder near Broek in Waterland. In 1980 leaking drums with a lot of dioxin were dug up there. The waste was not removed but covered over. Since 2011 the Volgermeerpolder has been a nature reserve.
The Netherlands: waste incineration
In the 1970s and 1980s dioxin was mainly known as air pollution from waste incinerators. It settles on the meadows and so ends up in cows. In 1989 milk from farms in the Lickebaert area near Maassluis and Vlaardingen contained more dioxin than the standard allowed. The source was the AVR waste incinerator in Rotterdam, at the time the largest known source of dioxin in the Netherlands. Since the end of 2005 a strict European standard has applied to emissions from waste incinerators. The fallout from the past is still in the soil.
Seveso, 1976
The best-known disaster happened in 1976 near the Italian town of Seveso: a cloud of dioxin escaped from a chemical plant. It was one scandal in a whole series.
Belgium, 1999
In 1999 recycled fat containing oil with PCBs was mixed into animal feed. The inspectors knew in April, but measures were only taken at the end of May. Chicken and eggs had to be taken off the shelves. In the Netherlands too, hundreds of products were withdrawn from sale. The Belgian ministers of Agriculture and Health resigned on 1 June 1999. Read more about the history of factory farming.
How can you take in less dioxin?
Dioxin builds up in animal fat. The WHO advises cutting the fat off meat, choosing low-fat dairy and eating a varied diet with vegetables, fruit and grains. The simplest way: replace meat, dairy and eggs with plant foods. Read also what the consequences of eating meat are and what you can do yourself.
Sources: WHO, fact sheet Dioxins (2026); EFSA, opinion on dioxins and dioxin-like PCBs (2026); Schoeters and Hoogenboom, Molecular Nutrition & Food Research (2006); RIKILT/RIVM, dioxins and PCBs in eggs from private chicken keepers (2014); NVWA/BuRO and WUR, meat from cattle on river floodplains (2020-2024); RIVM, dioxins in cow's milk near the AVR incinerator (1989-1990). Updated on 14 October 2026.
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