Polychlorinated dibenzofUrans human levels

Schecter, A., Furst, P., Furst, C., Meemken, H.A., Groebel, W., Constable, D., 1989a. Levels of polychlorinated dibenzofurans, dibenzodioxins, PCBs, DDT and DDE, hexachloro-benzene, dieldrin, hexachlorocyclohexanes and oxychlordane in human breast milk from the United States, Thailand, Vietnam, and Germany. Chemosphere 18, 445-454. 

Schecter A, Ryan JJ, Constable JD. 1987b. Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran levels in human breast milk from Vietnam compared with cow s milk and human breast milk from the North American continent. Chemosphere 16 2003-2016. 

Another major exposure route for humans is via contaminated food. For example, North America s Great Lakes, which are the largest body of freshwater in the world, are polluted with about 362 contaminants that were found in quantifiable amounts in the water, sediment, and biota (IJC 1983 USEPA 1994). The critical pollutants were identified as PCBs, DDT, dieldrin, toxaphene, mirex, methyl mercury, benzofa) pyrene, hexachlorobenzene, polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and alkylated lead. Some of these pollutants biomagnify in the aquatic food chain and can be detected in increased levels in cooked Great Lakes fish. Consequently, the blood serum levels of these chemicals are significantly increased in consumers of contaminated Great Lakes sport fish compared to people who do not eat such fish (Flumphrey 1983 Fiore et al. 1989 Sonzogni et al. 1991). 

Human poisonings from consumption of PCB mixtures include the well-known Yusho rice oil poisoning in Japan (1968), where PCB fluids became mixed inadvertently with rice oil used for cooking. The actual level of contamination of the rice oil was low, about 0.2%. About 2000 people were poisoned in 1978 in a similar incident in Yu-Cheng, Taiwan. The principal symptoms in both cases were related to headache. Adipose tissue from Yusho patients was found to contain up to 75 ppm of PCBs. Cancer development was not statistically connected with people poisoning by PCBs. Later investigations have shown that the toxicity of these PCB-contaminated rice oils was probably not primarily due to the PCBs themselves, but to the traces of polychlorinated dibenzofurans (PCDFs), which they contained. We will consider the formation of furans and dioxins in the following section. 

The severe health effects observed in the Japanese Yusho incident of 1968 were attributed to the ingestion of polychlorinated biphenyls (PCBs). At that time, the forefront of analytical chemistry was represented by the determination of trace components at the parts per million (ppm) concentration level. It was not until about ten years later that analytical methodology was able to detect polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzodioxins (PCDDs) at concentrations of 10 parts per billion (ppb) or less in the presence of PCBs. The significance of the determinations lies in the assessment of risk to human populations exposed to undegraded PCBs and to mixtures of chemically similar compounds of concern derived from uncontrolled reactions such as might occur when a PCB filled transformer undergoes eventful failure. 

Chao HR, Wang SL, Lee CC, Yu HY, Lu YK, Pake O (2004) Level of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls (PCDD/Fs, PCBs) in human milk and the input to infant body burden. Food Chem Toxicol 42(8) 1299-1308. doi 10.1016/j. fct.2004.03.008... 

Nakamura, H., Matsuda, M., Quynh, H.T., Cau, H.D., Chi, H.T.K., Wakimoto, T., 1994. Levels of polychlorinated dibenzo-p-dioxins, dibenzofurans, PCBs, DDTs and HCHs in human adipose tissue and breast milk from the south of Vietnam. Organohalo. Compd. 21, 71-76. 

Noren K. 1988. Changes in the levels of organochlorine pesticides, polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans in human milk from Stockholm, Sweden 1972-1985. Chemosphere 17 39-50. 

Patterson Jr. DG, Todd GD, Turner WE, et al. 1994. Levels of non-ortho-substituted (coplanar), mono-and di-ortho-substituted polychlorinated biphenyls, dibenzo-p-dioxins, and dibenzofurans in human serum and adipose tissue. Environ Health Perspect 102(supp 1) 195-204. 

Schecter A, Furst P, Ryan JJ, et al. 1989e. Polychlorinated dioxins and dibenzofurans levels from human milk from several locations in the United States, Germany, and Vietnam. Chemosphere 19 979-984. 

Schecter A, Ryan JJ. 1988. Polychlorinated dibenzo-p-dioxin and dibenzofuran levels in human adipose tissues from workers 32 years after occupational exposure to 2,3,7,8-TCDD. Chemosphere 17 915-920. 

Polychlorinated diphenyl ethers (PCDE) are common impurities in chlorophenol formulations, which were earlier used as fungicides, slimicides, and as wood preservatives. PCDEs are structurally and by physical properties similar to polychlorinated biphenyls (PCB). They have low water solubility and are lipophilic. PCDEs are quite resistant to degradation and are persistent in the environment. In the aquatic environment, PCDEs bioaccumulate. These compounds are found in sediment, mussel, fish, bird, and seal. PCDEs show biomagnification potential, since levels of PCDEs increase in species at higher trophic levels. PCDEs are also detected in human tissue. Despite the persistence and bio accumulation, the significance of PCDEs as environmental contaminants is uncertain. The acute toxicity and Ah-receptor-me-diated (aryl hydrocarbon) activity of PCDEs is low compared to those of polychlorinated di-benzo-p-dioxins (PCDD) and dibenzofurans (PCDF). Due to structural similarity to thyroid hormone, PCDEs could bind to thyroid hormone receptor and alter thyroid function. Furthermore, PCDEs might be metabolized to toxic metabolites. In the environment, it is possible that photolysis converts PCDEs to toxic PCDDs and PCDFs. 

Polychlorinated dioxins and dibenzofurans have been identified in technical products and pesticides, most of which are not very widely used today. Other sources are incinerators of various types like MSW incinera-" tors, but also hazardous waste incinerators and industrial incinerators. PCDDs and PCDFs have also been identified in exhausts from cars running on leaded gasoline with halogenated additives. Background levels of PCDDs and PCDFs have been identified in fish and other aquatic organisms from the Great Lakes and the Baltic Sea, and also in human adipose tissue samples from USA, Canada, Sweden, Japan and Vietnam as well as in samples of breast milk from Sweden,... 

Dioxins are a family of the most toxic chlorinated organic compounds known to science, numbering around 75 dioxins and 135 related furans. These can cause cancer and are ECD for humans, even at very low exposure levels, since minute amounts, can bio-accumulate due to their ease of solubility in body fat (dioxins are hydrophobic, water-hating and lipophilic, fat-loving ). Number and position of chlorine atoms in the molecule has a considerable effect on toxicity, and 17 dioxins are classed as highly toxic. These include polychlorinated dioxins (PCDD) and dibenzofurans (PCDF) which are by-products of the chlorine bleaching of paper, the burning of chlorinated hydrocarbons (such as pentachlorophenol, PCB, and PVC) and the incineration of municipal/medical... 

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