Human Exposure to Dioxin

The goal of this chapter is to identify the major sources of dioxin and related compounds, to identify the major pathways of human exposure and to estimate the extent of the resulting human exposure. 

Since dioxins and furans have varying levels of toxicity, emissions of mixtures of these compounds are typically expressed in TEQs (Toxic EQuivalents). TEQs relate the toxicity of all dioxin and furan compounds to the known toxicity of 2,3,7,8-TCDD using a weighting scheme adopted by the EPA and most European countries.1,2 Therefore, a quantity of combined PCDDs and PCDFs 

1 US Environmental Protection Agency, Interim Procedures for Estimating Risks Associated with Exposures to Mixtures of Chlorinated Dibenzo-p-dioxins and Dibenzofurans (CDDs and CDFs) and 1989 Update, 22161 PB90-145756, US Department of Commerce, National Technical Information Service, Springfield, VA, 1989. 

2 NATO, Pilot Study on International Information Exchange on Dioxins and Related Compounds Emissions of Dioxins and Related Compounds from Combustion and Incineration Sources, North Atlantic Treaty Organization, Committee on the Challenges of Modem Society, Report 172, August 1988. 

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Improper disposal of e-waste has been regarded as the major source of PCDD/ Fs occurring in China s environment [46]. Consequently, e-waste recycling should be somewhat responsible for human exposure to dioxins in China. A comparison of dioxins in human samples from e-waste recycling and reference sites would either confirm or disapprove the notion. The levels of PCDD/Fs (List 4 of Appendix) in human milk samples from a group of pregnant women... 

Charnley, G., Doull, J., 2005. Human exposure to dioxins from food, 1999-2002. Food Chem. Toxicol. 43, 671-679. 

Hattemer-Frey HA, Travis CC. 1989. Comparison of human exposure to dioxin from municipal waste incineration and background environmental contamination. Chemosphere 18 643-649. 

Travis CC, Hattemer-Frey HA. 1989. Human exposure to dioxin from municipal solid waste incineration. Waste Management 9 151-156. 

Although studies on human exposure to dioxin typically focus on products of animal origin,37 2 the accumulation of PCDD/Fs in vegetation is an important... 

Is Milk Packaging a Major Pathway of Human Exposure to Dioxin ... 

The food chain is the primary pathway of human exposure to dioxin, with meat (38%) and dairy products (28%) dominating. Fish ingestion can be a significant contributor in countries with high fish consumption (26% of total intake in the Netherlands), but is not an important factor in the US. The exact contribution of fruits and vegetables is unclear, but vegetable oil does appear to play a role in human dioxin exposure. Inhalation and consumption of contaminated water and soil are not major sources of human exposure to TCDD. 

There have been a number of cases of known human exposure to dioxin, mostly as a result of industrial accidents. The first reported human exposure to dioxin resulted from an accident at a plant making the herbicide 2,4,5-T in 1949 in Nitro, West Virginia. More than 120 workers were... 

Direct human exposure to dioxin occurred in southern Vietnam and also in Seveso, Italy. It was estimated that southern Vietnam has been contaminated by 160 to 600 kg of dioxin as a result of 80 million liters of defoliant herbicides (Agent Orange, a 50 50 mixture of 2,4,5-T and 2,4-D) being sprayed by the US military over a large area of... 

Tier 5 sampling was generally limited to those areas where the use of 2,4,5-T or Silvex has been documented, since information from the EPA Office of Pesticide Programs indicated that these two compounds have been more heavily used in specific areas and thus have a greater potential for causing significant human exposure to dioxin. The other compounds were of lesser interest due to ... 

A historical review of studies of human exposure to dioxin-contaminated substances is presented, with emphasis on 2,3,7,8-tetrachlorodibenzodioxin (2,3,7,8-TCDD). Exposed populations include production workers, herbicide sprayers, persons exposed to Agent Orange, and residents of Missouri,... 

The wide dispersal of the dioxin-like chemicals throughout the environment is primarily the result of atmospheric transport and deposition. Eventually the dioxin-Uke chemicals become adsorbed to dust particles and surfaces and are deposited in sediments. The two primary pathways for dioxin-like chemicals to enter the food chain are from the air-to-plant-to-animal and from water-and sediment-to-fish. A third route for dioxin-Uke chemicals to enter the food chain is through the accidental contamination incidents resulting from inappropriate handling and processing of feed and food substances. It has been estimated that more than 90% of human exposure to dioxin and dioxin-like chemicals is through the ingestion of contaminated food substances. ... 

Trace dioxins have been detected in soil, sediment, vegetation, fruits, fish and mammalian tissne, and bovine milk. 2,3,7,8-snbstitnted isomers and other polychlorinated dibenzo-p-dioxin and polychlorinated diben-zofurans have been detected in the snrface samples at many PCBs disposal facilities. The major source of human exposure to dioxin is the food chain. Dioxins bioaccumulate in adipose tissue in humans. According to an estimate, the long-term average daily intake of dioxin in humans is 0.05 ng/day (Hattemer-Frey and Travis 1987). 

Human exposure to dioxins stems from the food chain (> 90 %), from the ingestion of milk, dairy products, meat and fish, all containing dioxins. The ADI-value (Acceptable Daily Intake) is in the order of 1 picogram per kilogram of body-weight. 

Over the past 30 years, dioxin TEQ levels and body-burden levels in the general population have been on the decline and continue to decrease (Lorber, 2002). But, more than 90% of human exposure to dioxins and dioxin-like substances is through food, mainly meat and dairy products, fish and shellfish, and hence lead to continuous control (WHO 2014). With increasingly lower dioxin levels in food, feed and tissues, more demanding LOD, selectivity, sensitivity and QC checks are required to trace their presence at these further decreasing levels. 

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