dioxinien

Dioxinien, often referred to in English as dioxins, are a group of chemically related chlorinated organic compounds that share a dibenzo-p-dioxin or dibenzofuran backbone. The term covers polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The core structure consists of two benzene rings joined by two oxygen atoms; chlorine atoms substitute at multiple positions, producing a large number of congeners and isomers.

Most dioxin compounds are highly toxic, with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) used as the reference congener. Dioxin-like compounds act mainly by binding to the aryl hydrocarbon receptor (AhR), altering gene transcription and enzyme activity. This can affect development, immune function, metabolism and increase cancer risk in animal studies.

Dioxins enter the environment as by-products of combustion and certain industrial processes, including waste incineration, metal production, chlorine bleaching and some chemical syntheses. They are very persistent and accumulate in fatty tissues. Human exposure occurs mainly through the diet, especially fatty animal products such as meat, dairy and fish; inhalation and soil ingestion contribute as well.

They are lipophilic and persist in soils and sediments, and they biomagnify in food chains. Regulation: the Stockholm Convention aims to reduce releases and eventual elimination; risk assessment uses toxic equivalency (TEQ) to express combined dioxin-like activity; analysis uses GC-MS or HRGC/HRMS.