Polychlorinated biphenyls food chain

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) ai e toxic compounds of anthropogenous origin, able to accumulate in tissues of alive organisms and to cause different diseases. These compounds ai e the most dangerous for aquatic ecosystems as they easily adsorb in sludge and ai e included in food chains of biota. Humans consume PCBs and OCPs mostly with fish. 

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. 

Heavy metals may also be concentrated in passage up the food chain. Other pollutants, e.g. fungicides, pesticides, biocides, polychlorinated biphenyls or organic mercury compounds, are persistent and can therefore also bioaccumulate. 

Focardi, S., C. Leonzio, and C. Fossi. 1988b. Variations in polychlorinated biphenyl congener composition in eggs of Mediterranean water birds in relation to their position in the food chain. Environ. Pollut. 52 243-255. 

Muir, D.C.G., R.J. Norstrom, and M. Simon. 1988. Qrganochlorine contaminants in Arctic marine food chains accumulation of specific polychlorinated biphenyls and chlordane-related compounds. Environ. Sci. Technol. 22 1071-1079. 

The formation of polar metabolites from nonpolar materials may actually facilitate monitoring programs—in many cases the polar chemicals are highly concentrated in certain body fluids such as bile and urine. On the other hand, materials such as certain cyclodienes and polychlorinated biphenyls, which are very lipid soluble and resistant to metabolism, may accumulate and these chemicals may persist in the environment and may be transferred via the food chain to man. There is also interest in these biotransformation processes in lower organisms since the simplicity of these systems may lead to a better understanding of the phylogenetic development of xenobiotic metabolism. 

PIO Polychlorinated biphenyls (PCBs) are a group of pollutants widely distributed in the environment due to their generous use in the past, their lipophilic character, and their chemical stabilityd Thus, PCBs have a long environmental half-life and tend to accumulate in the food chains the highest concentrations were usually found in human beings and higher animals at the top of the food chaind- ... 

Overview and Importance. The pollutants known as polychlorinated biphenyls (PCBs) are widely distributed in the environment due to their extensive use in the past, lipophilic (fet-loving) character, and general chemical stability. Moreover, PCBs tend to accumulate in the food chain. Thus, several countries have established recommended maximum limits for PCBs in food products. Among these products, milk is especially important because of its extensive and widespread consun tion by humans. 

The polychlorinated biphenyls (PCBs, coplanar biphenyls) have been used in a large variety of applications as dielectric and heat transfer fluids, lubricating oils, plasticizers, wax extenders, and flame retardants. Their industrial use and manufacture in the USA were terminated by 1977. Unfortunately, PCBs persist in the environment. The products used commercially were actually mixtures of PCB isomers and homologs containing 12-68% chlorine. These chemicals are highly stable and highly lipophilic, poorly metabolized, and very resistant to environmental degradation they bioaccumulate in food chains. Food is the major source of PCB residues in humans. 

Polychlorinated biphenyls (PCBs) have been known for sometime as persistent pollutants, which can be readily bioaccumulated through the food chain causing well-documented toxic effects in number of species including humans [191]. Consequently, PCBs are commonly routinely monitored as potential industrial pollutants. Due to their environmental persistence and toxicity, detection limits in the ng ml-1 region are generally required. Consequently, such work has generally required solvent or solid extraction and concentration steps prior to separation by GC in conjunction with electron capture detection, or mass... 

Where analytical methods are available it is largely because of a crossfertilisation of effort from well-established areas of food contaminants work. For example, the steady development since the 1960s of methods of analysis for chlorinated pesticides led to the analysis of food for polychlorinated biphenyls (PCBs) since PCBs were readily detectable by general methods used to analyse food for organochlorine pesticides. The analysis of food for chlorinated dioxins and furans (PCDDs and PCDFs) at the very low levels at which they are found in food is a more recent development, and one that is an important precedent since it arose from interest in environmental contamination rather than because of cross-fertilisation of scientific methodology from an established area of food chemistry. Although dioxins were detectable some years ago at much less sensitivity in some pesticides, it was environmental interest that led to their study at very low levels in the food chain. 

The toxicity, bioaccumulative potential, and ecological impact of organohalogenated substances such as polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), polychlorinated d iben zo -pa ra - diox i n s (PCDDs), or polybrominated diphenylethers (PBDEs) have been extensively reviewed.95 98 All are referred to as persistent organic pollutants (POPs), that is, chemical substances that remain in the environment, bioaccumulate through the food chain, and pose a risk to human health and the environment. The international community is calling for action to reduce and then eliminate the production or formation of these substances and to monitor their emission. In this case, the detectability obtainable by analytical methods should be very low, since the limits established for these residues are in the ng per liter range. 

Bloomington, Indiana Polychlorinated biphenyls (PCB s) Industrial waste contaminating municipal sewage used for garden manure Direct contact and possibly food chain... 

The polychlorinated biphenyls occur widely as environmental pollutants and have been observed in the food chain. GC-MS has been applied in various aspects of their analysis (for leading references see [504, 505,513]). In the general area of food chemistry and contamination control, claims for the presence of carcinogenic nitrosamines in foodstuffs have been evaluated by specific GC-MS techniques [514,515]. However, it has been suggested that there may be a current over obsessive interest in the possible hazards of a few ppb of nitrosoamines in food [516]. 

Bioconcentration in the marine food chain can lead to animals such as seals, beluga whales, seabirds, and polar bears having concentrations of to-xaphene 10 million times higher than levels in the surrounding water. For polychlorinated biphenyls (PCBs), the amplification is 1000 million times. 

Hansen LG. 1987a. Food chain modification of the composition and toxicity of polychlorinated biphenyl (PCB) residues. Rev Environ Toxicol 3 149-212. 

Connolly, J.P. 1991. Application of a food chain model to polychlorinated biphenyl contamination of the lobster and winter flounder food chains in New Bedford Harbor. Environ. Sci. Technol. 25 760-770. 

The polychlorinated biphenyls (PCBs) are synthetic organic chemicals with main sources in the environment being the processes of combustion and incineration (WHO, 1993). The organochlorine pesticides (OCPs), although banned internationally, can still be found in many environmental samples. Both classes of compounds are very persistent, tend to accumulate in the food chain and have negative effect on the human health (Cousins et al., 1998 Wade et al., 2002). For that reason many efforts have been made... 

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