Dioxines and furans (PCDDs and PCDFs)
Dioxins/furans are a family of complex chemicals containing chlorine, known as polychlorinated-p-dioxins (PCDDs) and the related furans (PCDFs). There are several hundred dioxins and furans. Some dioxin/furan substances ('congeners') are toxic at very low levels. The most toxic one is 2,3,7,8-tetrachloro-dibenzo-p-dioxin, which is often referred to as 2,3,7,8-TCDD.
PCDDs and PCDFs are crystalline solids, virtually insoluble in water, but readily soluble in organic solvents, fats and oils.
Dioxins/furans have never been intentionally manufactured, other than for research and analytical purposes and have no other uses.
The most significant sources of release to the air include accidental fires and open burning of agricultural wastes, iron and steel works, power stations and vehicles. Incineration of waste used to be the biggest single source of emissions into the atmosphere. Modern incinerators however are equipped with flue-gas cleaning and/or afterburning technology required to achieve an emission limit of 0.1 nanogram I-TEQ (i.e. one thousand millionth of a gram) of dioxin per cubic meter of stack gas.
Impacts on human health and environment
Excessive exposure to dioxins/furans may cause health effects on the heart, immune system, liver, skin, thyroid gland, unborn child, and may cause cancer.
Once released into the atmosphere, dioxins/furans exist both in the gas phase and bound to tiny particles. They eventually deposit onto soil and vegetation. Being highly insoluble in water, dioxins/furans adsorb strongly to soils or sediments, are resistant to leaching out, and degrade very slowly, so persisting for many years. Dioxins/furans deposited onto grass (and to a lesser extent, soil) may be taken up by livestock and enter the human food chain ending up in milk and meat. Dioxins/furans in aquatic sediments can also enter the human food chain via fish. A wide range of toxicological effects has been observed in wildlife experimentally exposed to dioxins/furans. They range from acute to chronic effects and include reduction in reproductive success, growth defects, immune system suppression and cancer.
Some dioxins/furans are able to travel long distances through the atmosphere, and dioxins adsorbed onto particles may be transported large distances by rivers meaning that they may be encountered at locations remote from their emission source. They are characterised by their resistance to decomposition (persistence), their ability to concentrate through the food chain (bioaccumulation) and their toxicity. This has lead to the categorisation of dioxins/furans as 'Persistent Organic Pollutants'(POPs), which are subject to international treaty agreements to reduce exposure.
Emission to air reporting threshold: 0 kg/year
Data source: European Pollutant Emission Register