Bioaccumulation, chlorinated

Food Chain Bioaccumulation. Chlorine dioxide and chlorite (ions and salts) are strong oxidizers and will not bioaccumulate. 

The contamination of sediments may pose an unacceptable risk to aquatic organisms, which tend to bioaccumulate chlorinated and brominated POPs, and to wildlife and humans through the ingestion of contaminated fish and shellfish. During the last foiu decades a large amount of environmental data... 

Borga, K., Hop, H., and Skaare, J.U. et al. (2007). Selective bioaccumulation of chlorinated pesticides and metabohtes in Arctic seabirds. Environmental Pollution 145, 545-553. 

There is a vast range of aqueous organic pollutants with a wide toxicity profile. Some, e.g. polychlorinated biphenyls, certain herbicides, fungicides and pesticides, and organo-mercury compounds, are persistent and may bioaccumulate in the food chain. Trace contaminants such as sodium chloride, iron and phenols (especially if chlorinated) may also impart a taste to water. Typical consent levels for industrial discharges are provided in Table 13.10. 

Saisho K, Hasegawa Y, Saeki M, et al. 1994. Bioaccumulation of volatile chlorinated hydrocarbons in blue... 

The KoW data in Figure 1.7.12 show that the chlorophenols and alkylphenols differ in properties, there being more uncertainty about the KoW of the longer-chain phenols. The chlorophenols tend to partition more into octanol at the same molar volume and are thus expected to be more bioaccumulative. The slope of the chlorophenol line is about 0.78 log units per chlorine or a factor of 6.0. The alkylphenol slope is lower and about 0.36 log units per CH2, i.e., a factor of 2.3. 

Owens, J.W., S.M. Swanson, and D.A. Birkholz. 1994. Bioaccumulation of 2,3,7,8-tetrachlorodibenzo-/>-dioxin, 2,3,7,8-tetrachlorodibenzofuran and extractable organic chlorine at a bleached-kraft mill site in a northern Canadian river system. Environ. Toxicol. Chem. 13 343-354. 

Gobas, F.A.P.C., D.C. Bedard, J.J.H. Cibrowski, and G.D. Haffner. 1989. Bioaccumulation of chlorinated hydrocarbons by the mayfly (Hexagenia limbata) in Lake St. Clair. Jour. Great Lakes Res. 15 581-588. 

The number of chlorine atoms in each molecule can vary from one to eight. Among the possible 210 compounds, 17 congeners have chlorine atoms at least in the positions 2, 3, 7 and 8 of the parent molecule and these are the most toxic, bioaccumulative and persistent ones compared to congeners lacking this configuration. All the 2,3,7,8-substituted PCDDs and PCDFs plus coplanar PCBs (with no chlorine substitution at the ortho positions) show the same type of biological and toxic response. 

The presence of chlorine and chlorinated compounds is also the source of dioxins and furans during paper making, and these compounds have been detected in sediments in the vicinity of a pulp and paper mill [53] and in effluents, along with polychlorinated dibenzothiophenes [54]. A recent study found high concentrations of PCDD and PCDF along with PCP in nestling tissue (Tachycineta bicolor) collected downstream of paper pulp mills, suggesting that the primary source of contaminants was the use of PCP for timber preservation [55]. In addition, it has been shown that dioxins bioaccumulate in fish downstream of pulp and paper mills [56]. The levels of chlorinated compounds of different families are shown in Fig. 3. 

The water insoluble, highly chemically and thermally stable PCBs used as insulating fluids for transformers and capacitors, in paints, copy paper, etc., are extremely toxic, persistent in the environment and bioaccumulating. PCBs are currently destroyed by incineration of concentrates at high temperatures or chemically with sodium metals or organosodium. Both processes are costly. The cathodic reduction/elimination of the chlorine from polychlorinated biphenyl... 

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. 

Thus it can be seen that the mean concentration of DAS1 plus DSBP (pg kgy 1) in sediments is some 16000 times greater than it is in the overlying water layer. In the case of BLS this factor exceeds 250000. Similar large factors have been observed in the case of chlorinated insecticides in river waters i.e. bioaccumulation factors of the order of 104. 

Young DR, Gossett RW, Baird RB, et al. 1983. Wastewater inputs and marine bioaccumulation of priority pollutants organics off southern California. In Water Chlorination Environ Impact Health Eff 4 871-884. 

Villeneuve, J.Y. Niimi, A.J. Metcalfe, C.D. 2000, Distribution and bioaccumulation of chlorinated diphenyl ethers in a contaminated embayment of Lake Ontario. J. Great Lakes Res. 25 760-771. 

Chlorinated micropoUutants are harmful for man and environment due to their toxicity, persistence, and bioaccumulation. Persistent compounds are very stable and difficult to get metabolized and mineralized by biological and chemical processes in the environment, and as a result, they have become ubiquitous in water, sediments, and the atmosphere bioaccumulation is the result of the lipophilicity of these compounds. Polychlorinated dibenzodioxins and -furans (PCDD/F) are not produced purposely like many of other chlorinated technical products, such as chlorinated biocides DDT, lindane, and toxaphene. The production and use of persistent organic pollutants (POPs), the dirty dozen has now been banned worldwide by the Stockholm protocol. It should be mentioned that about 3000 halogenated products have now been isolated as natural products in plants, microorganisms, and animals," but the total amount of these products is much smaller compared to xenobiotics. 

All PCDD/F isomers are solids with high melting points, but low vapor pressure and low solubihty in water. The high octanol-water coefficients are an indication of the observed bioaccumulative behavior in plants and animals for these compounds. Detailed environmentally important physicochemical properties can be found in the literature. All higher chlorinated compounds are very persistent in the environment with half-lives of 5-10 years photolysis with sunlight is the only degradation process in the environment. 

The so-called persistent organic pollutants (POPs) are the subject of the Rio Declaration (1994) and the Stockholm Convention (2001) these international agreements (yet to be ratified in all signatory countries, including the United States) call for the elimination from production of 12 persistent chemicals, including the chlorinated pesticides and PCBs mentioned above (all of which have already been eliminated from production in the United States). Current regulatory efforts in the European Union and the United States place emphasis on elimination or restriction of all PBTs (persistent, bioaccumulative, and toxic chemicals). 

Californian standards by switching three years ago to melamine combined with chlorinated paraffins. Melamine is not a bioaccumulative or persistent material. They are now researching alternatives to chlorinated paraffins, including the use of novel substances, such as expanded graphite. IKEA is conducting this research in isolation in the USA and points out that the cost of new substitution will be high unless other upholstery designers and retailers follow suit. ... 

Kopperman HL, Keuhl DW, Glass GE. 1978. Chlorinated compounds found in waste treatment effluents and their capacity to bioaccumulate. In Jolley RL, ed. Water chlorination Environmental impact and health effects. Volume 1. Aim Arbor, MI Ann Arbor Science Publishers, Inc., 311-328. 

It turns out that most of these compounds have similar characteristics that contribute to their toxicity to both humans and other species of plants and animals. First, the compounds are environmentally persistent. Many of the early pesticides, and certainly the metals, do not break down in the environment or do so only very slowly. If persistent chemicals are released continually to the environment, the levels tend to rise ever higher. This means they are available to cause harm to other organisms, often not even the target of the pesticide. Second, the early pesticides were broad acting and toxic to many species, not just the target species. These poisons often killed beneficial insects or plants. Third, many of these compounds would bioaccumulate or concentrate in species as they moved up the food chain. The chlorinated pesticides accumulate in the fat of animals. Animals that consumed other animals accumulated more and more of these pesticides. Most species could not metabolize or break down the compounds. Lead accumulates in bone and methyl mercury in muscle. And finally, because of their persistence in the environment and accumulation in various species, the persistent toxicants spread around the world even to places that never used them. Animals at the top of the food chain, such as polar bears and beluga whales, routinely have fat PCB levels greater that 6 ppm. 

Further investigation is needed to determine the fate of contaminants accumulated during phytoremediation. Evidence has shown that poplar trees degrade chlorinated solvents, such as trichloroethylene (TCE), through naturally occurring metabolic processes. The by-products, possibly carbon dioxide and chloride salts, may be stored in the tissues of the trees. It is not yet certain, however, the fate of many chemicals and metals. Contaminants that collect in the leaves may be released when the leaves drop, or may be eaten by animals and consequently bioaccumulated through the food chain. 

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