A review of the significance of animal food products as potential pathways of human exposures to dioxins

Abstract

The polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are groups of compounds with similar chemical and toxicological properties. Carcinogenicity was considered the most serious toxic end point when setting previous regulatory policies, but recent concerns have focused on the possible endocrine-disrupting activities of the dioxins. Toxicity is related to the 2,3,7,8 pattern of chlorine substitution, a pattern that also leads to chemical and metabolic stability. Dioxins are practically insoluble in water and concentrate in lipids of biological systems, leading to low background concentrations in fat of the general human population. Major environmental sources of dioxins are emissions from industrial chlorination processes and combustion of materials containing chlorine. Inhalation and water have been ruled out as significant exposure pathways, which suggests that food is the primary source. Pathways of entry into food chains are atmospheric transport of emissions and their subsequent deposition on plants, soils, and water. The major food sources seem to be fat-containing animal products and some seafoods. This conclusion is based on evaluations of potential environmental pathways involving dioxins and related compounds. Generally, dioxins and other lipophilic compounds are not taken up and translocated by plants, so residues in foods and feeds derived from seeds should be negligible. Animals on high-roughage diets, or those that ingest contaminated soil, are the most likely to accumulate dioxin residues from the environment. The conclusion that animal products are a major source of human exposure requires verification by appropriate food sampling programs and animal metabolism studies. If it is desirable to reduce human exposure to dioxins via the food supply, reduction of sources would be a more effective strategy than changing agricultural practices and food consumption patterns.

Internal exposure to pollutants measured in blood and urine of Flemish adolescents in function of area of residence

“…Interestingly, consumption of locally produced food items was positively correlated with concentrations of PCBs, DDE and HCB, suggesting higher pollutant burdens in such food. It is known that fat intake is to a large extent responsible for contamination with persistent lipophilic pollutants (Fries, 1995) and that vegetable food is an important factor in contamination with heavy metals (Muñ oz et al, 2005). The variation in age between adolescents in this study was too small to have a significant effect of age on the internal exposure levels as seen in some other studies.…”

Organochlorine and heavy metals in newborns: Results from the Flemish Environment and Health Survey (FLEHS 2002–2006)

“…low density of population (b250 inhabitants/km 2 ) less than 5% of the area occupied by industry, no registered pollution sources, no major highways. The main route of intake of these OCs is supposed to be consumption of animal/fish products (Fries, 1995;Liem et al, 2000;Parzefall, 2002). However, intake of animal fat-containing food items showed little variation across the participating mothers (P 25 -P 75 =22 to 42 gram animal+fish fat per day) and did therefore not explain the higher cord blood levels of OCs in participants from the rural area.…”

The relation between the estimated dietary intake of PCDD/Fs and levels in blood in a Flemish population (50–65 years)

“…It is widely accepted that the diet is responsible for more than 90% of the exposure to dioxin-like contaminants in the general population (Fries 1995;Liem et al, 2000;Päpke, 1998;Parzefall 2002). Therefore, a dietary intake assessment is often performed as an exposure and risk estimate for the general population regarding this type of contaminants (Bilau et al, 2008;Bocio and Domingo, 2005;Charnley and Doull, 2005;Darnerud et al, 2006;Fattore et al, 2006;Kiviranta et al, 2004;Sasamoto et al, 2006;Taioli et al, 2005;Vrijens et al, 2002).…”

“…Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) (further referred to as: dioxins) are a group of lipophilic contaminants, generated unintentionally as by-products from human activities, such as various industrial chemical reactions and combustion processes, including waste incineration. They recycle between air, water, soil, sediments and waste (Fries, 1995). Dioxins in air bind to small size particles and are deposited on fields and plants and are resistant to environmental and biological degradation.…”

“…It is known that dietary intake is the most important source of human exposure: at least 90% of total exposure to dioxin-like contaminants can be attributed to dietary intake of food items of animal origin (Fries, 1995;Liem et al, 2000;Parzefall, 2002). Within the context of this biomonitoring program, a dietary intake assessment of animal fat has been evaluated, which allowed us to estimate the intake of dioxin-like contaminants through food (Bilau et al, 2008).…”