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. (Source: WHO)