Dioxins are complex chemicals containing chlorine. Some are toxic even at very low concentrations. Dioxins belong to the family of Persistent Organic Pollutants. They are characterised by their resistance to decomposition, their ability to concentrate through the food chain and their toxicity. The Seveso accident with the emissions of the dioxin (TDCC) in 1976 was the initiators for the EU Directive on the major-accident hazards – the Seveso Directive – in 1982.
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Common name: Dioxins are the generic term for closely related substances - 75 dibenzopdioxiner (PCDD) and 135 dibenzofuraner (PCDF).
Use
Dioxins have never been intentionally manufactured commercially - only for research purposes. But they are formed by a number of human activities e.g. in many types of uncontrolled combustion processes.
Releases to the environment
The most significant sources of release to the air include incineration of waste, iron and steel works, power stations and motor vehicles. Incineration of waste used to be the biggest single source of emissions into the atmosphere, but reduces due to better cleaning technology.
Impacts on the environment and human health
TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) is the most toxic dioxin. The other PCDDs and PCDFs have the same effect, but are less hazardous with major individual differences. Excessive exposure to dioxins may affect the heart, immune system, liver, skin, thyroid gland and the unborn child, and may cause cancer. Once released into the atmosphere they eventually deposit onto soil and vegetation and degrade very slowly. Over 95% of human exposure to dioxins come through the food chain, mostly through the consumption of meat, fish and dairy products.
International actions
Dioxin is listed in the Seveso directive and in the UNECE Protocol on Persistent Organic Pollutants – the POP Protocol. Furthermore dioxin is on the EU-Commissions EPER list and listed in the PRTR Protocol under the Århus Convention.
CAS NO: Not applicable for a group of substances as dioxins.