[Diet as a source of human exposure to polychlorinated dibenzo-P-dioxins (PCDD)]

Dioxins are highly toxic by-products of many industrial processes e.g. chemical and municipal waste incineration or production of chlorophenols. These compounds penetrate the environment via air, water and soil and are then incorporated in food chains. The major source of human exposure (90% of total exposition) is consumption of a wide variety of common foods (meat, fish and dairy products) containing small amounts of dioxins. The average daily intake of PCDD via food was estimated in the range of 1-3 pg/kg bw. Common characteristics of all congeners detected in foodstuffs were 2,3,7,8-chlorine substitution. Commercial milk samples could be contaminated by PCDD/DFs present in the pulp used for the production of the milk cartoon. Also higher levels of these xenobiotics were found in samples from cows grazing in the vicinity of incinerators as compared to samples from rural farms. Human exposure to dioxin begins early in life since breast-feeding is the best way to nourish an infant. The nursing baby in developed countries get a particularly high dose of dioxins (about 85 pg TEQ/kg bw/day). Food contamination with dioxins leads to enhanced accumulation of these compounds in human tissues to the extent of exceeding acceptable level.