Dioxins biota

Smith, L.S., T.R. Schwartz, K. Felz, and T.J. Kubiak. 1990. Determination and occurrence of AHH-active polychlorinated biphenyls, 2,3,7,8-tetrachloro-/>-dioxin and 2,3,7,8-tetrachlorodibenzofuran in Lake Michigan sediment and biota. The question of their relative toxicological significance. Chemosphere 21 1063-1085. 

The chlorinated chemicals assessed do not have the same risk profile. For the more volatile chemicals the safety margins between the actual exposure and the level at which no effect on the environment would be expected is quite high. For more persistent chemicals there is a need to look to the environmental compartment where they can be accumulated (mainly in sediments and biota). For some of these chemicals the safety margin is quite low and in worst-case situations serious effects may occur. For the very persistent, bioaccumulative and toxic chemicals (like dioxins, PCBs and DDT), acceptable environmental concentrations are so low and difficult to control that the industry is committed to reducing as far as possible releases to the environment through application of Best Available Techniques (BAT), mainly with respect to dioxins. For other chemicals (PCBs, DDT), production has already been halted for some years. 

HOEC (log 10) dioxin-eflTects in biota [pg TEQ/kg lipid weight)... 

Extensive efforts have been made in the environmental monitoring of dioxins from 1989 in biota and sediments and from 1998 in other media until present (Fig. 1.2) (Ministry of the Environment, 2002, Dioxins monitoring in the environment ). It could be seen from these efforts, that emission of dioxins in Japan has been decreasing from 7680-8135 g-TEQ in 1997 to 323-348 g-TEQ in 2005, a 95% reduction from the 1997 level, meeting the reduction target (Ministry of the Environment, 2004, Dioxin emission inventory ). In 2005, 3206 atmospheric samples, 2550 water samples, 1730 sediment samples, 924 ground water samples and 1782 soil samples were analyzed for their dioxin levels. 

Litten, S., McReynolds, D., Swart, J., Estabrooks, F., Hoover, D., Hamilton, C., 2003. Chlorinated dioxin/furans in New York harbour water, wastewater, biota, and sediments. Organohalo. Compd. 62, 169-172. 

Wong, H.L., Giesy, J.P., Siu, W.H.L., Lam, P.K.S., 2005. Estrogenic and dioxin-like activities and cytotoxicity of sediments and biota from Hong Kong mudflats. Arch. Environ. Contam. Toxicol. 48, 575-586. 

Shan, G., W.R. Leeman, S.J. Gee, et al. 2001. Highly sensitive dioxin immunoassay and its application to soil and biota samples. Anal. Chim. Acta 444 169-178. 

Muir, D.C.G., Lawrence, S., Holoka, M., Fairchild, W.L., Segstro, M.D., Webster, G.R.B., Servos, M.R. (1992) Partitioning of polychlorinated dioxins and furans between water, sediments and biota in lake mesocosms. Chemosphere 25, 119-124. 

Dioxins and furans in biota near 46 puop and paper mills using the chlorine bleaching process. Chemosphere 27(l-3) 279-86. 

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) have over the last 15 years been the subject of intense environmental chemistry research. This interest is rooted in the persistence and hydrophobicity of these compounds, which impart to them a strong tendency to bioaccumulate. This, coupled with the fact that a number of PCDD/Fs have been found to be toxic at very low concentrations, has fuelled interest in understanding their behaviour in the environment. One crucial component of the environmental behaviour is the biological uptake and transfer of PCDD/Fs, since this determines the exposure of biota to these compounds. 

Muir DCG, Lawrence S, Holoka M, Fairchild WL, Segstro M, Webster GRB, Servos MR (1991), DIOXIN 9T. Abstract 44. Partitioning of polychlorinated dioxins and furans between water, sediments and biota in lake mesocoms", Research Triangle Park, USA Podoll RT, Jaber HM, MillT (1986), Environ. Sci. Technol. 20 490-492. Tetrachlorodibenzodi-oxin Rates of volatilization and photolysis in the environment"... 

A legacy of the use of an estimated 600 kg of the herbicide Agent Orange during the conflict in Vietnam has been the contamination of soil, rivers, sediment and biota with dioxins [53, 54]. Hot spots of contaminated soils in the Aluoi Valley and other former US bases where the pesticides were stored have recently been identified [53]. These sites have considerably higher dioxin levels compared with regions where dioxins were aerially sprayed. These sites, if not cleaned up, will be a continued source of dioxins to the local environment for the foreseeable future. 

PBDEs are a class of chemicals widely used as flame retardants in a variety of applications. They are ubiquitous in the environment and have been detected in various environmental media including air [76, 77], water [78], biota [1, 79], soil [80], sediments [81, 82], house dust [83,84], cars [85], humans [86] and sewage sludge [87]. PBDEs are similar in molecular structure to several well-known POPs such as PCBs and dioxins/furans. They have very similar physicochemical properties and, like these compounds, PBDEs are of environmental concern because of their high lipophilicity, persistence and resistance to degradation [88-90]. 

The major purpose of biotransformation is to chemically modify (metabolize) poorly excretable lipophilic compounds to more hydrophilic chemicals that are readily excreted in urine and/or bile. Without metabolism, lipophilic xenobiotics accumulate in biota, increasing the potential for toxicity. Examples of such compounds are highly halogenated polychlorinated biphenyls (PCBs) and polychlorinated dibenzofu-rans (TCDD and dioxins) that occur as tissue residues in humans. On the contrary, biotransformation is normally not required for xenobiotics with high water solubility because of rapid excretion in urine. 

Zhao X, Zheng M, Zhang B, et al. Evidence for the transfer of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and poly chlorinated dibenzofurans from soils to biota. Sci Total Environ 2006 368(2-3) 744-52. 

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