International Programme on Chemical Safety

Dioxins and dioxin-like substances


Dioxins and dioxin-like substances, including PCBs, are persistent organic pollutants (POPs) covered by the Stockholm Convention. They can travel long distances from the source of emission, and bioaccumulate in food chains.

Human exposure to dioxins and dioxin-like substances has been associated with a range of toxic effects, including immunotoxicity, developmental and neurodevelopmental effects, and changes in thyroid and steroid hormones and reproductive function. Developmental effects are the most sensitive toxic endpoint making children, particularly breast-fed infants, the population most at risk.

These substances are byproducts of combustion and various industrial processes, such as chlorine bleaching of paper pulp and smelting. While manufacture of PCBs should have been discontinued, release into the environment still occurs from disposal of large scale electrical equipment and waste. Human exposure to dioxin and dioxin-like substances occurs mainly through consumption of contaminated food.

Actions to reduce emissions of these substances are required by the Stockholm Convention. Interventions to reduce human exposure include:

  • identifying and safely disposing of material containing or likely to generate dioxin and dioxin-like substances such as electrical equipment;
  • ensuring appropriate combustion practices to prevent emissions;
  • implementing FAO/WHO strategies to reduce contamination in food and feed; and
  • monitoring of food items and human milk.

Short information documents for decision makers

Tools for action

Norms and guidance values

Fact sheets

Educational material