dioxin chemistry and biology

Dioxins are polychlorinated dibenzodioxins, formed from two benzene rings joined by 2 oxygen bridges, forming an aromatic ether. These are environmental pollutants and are teratogens, mutagens and possibly carcinogens. They are fat soluble and accumulate in mammalian tissues , giving them a prolonged biological life.
Chlorine atoms are attached at 8 different sites at positions 1-4 and 6-9. There are more than 75 cogeners of dioxin, where dioxin have chlorine at 2,3,7 and 8 positions there is enhanced toxicity.
Dioxins originate from the incineration of chlorine containing substances such as polyvinyl chloride, in the bleaching of paper and from natural events e.g. volcanoes and forest fires. Open burning of wood, waste, and diesel emissions are important sources of dioxin. Dioxins are to be found in cigarette smoke.
Dioxins enter the human body by eating food especially fish, meat and dairy products. The fat solubility of dioxin holds dioxin in the food chain. Dioxins are an occupational risk during herbicide use. Dioxin may be transposed to children through breast milk. This persists for 6-8 years. The lipid accumulation of dioxins is a major factor in the accumulative toxicity of these substances with a half life of 8 years.
Toxicity includes
Increase tumour incidence
Developmental abnormalities
Thyroid disorders
Immune problems
Altering the male to female ratio in babies in an at risk population.
Skin lesions

Martin Eastwood
Back to top