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PCBs may play a role in the development of cancers of the immune system because some tests of laboratory animals subjected to very high doses of PCBs have shown effects on the animals' immune system, and some studies of human populations have reported an association between environmental levels of PCBs and immune response.
Humans and wildlife are rarely exposed to solitary contaminants, but rather to complex mixtures of potentially harmful compounds. Dioxins and DLCs are no exception. [ 3 ] This is important to consider when assessing toxicity because the effects of chemicals in a mixture are often different from when acting alone.
PCBs are human carcinogens, and can also have a negative effect on the human immune, reproductive, and endocrine systems. [4] PCBs in the Kalamazoo River adhere to the fatty tissue of fish, and over time a process of bioaccumulation takes place, meaning that the PCBs appear in increasing concentrations in organisms higher up on the food chain ...
Exposure to the coplanar stereoisomer 3,3',4,4',5,5'-hexabromobiphenyl (but not the non-coplanar stereoisomer) in genetically susceptible mice is known to cause immunotoxicity and disorders related to the central nervous system, and even at doses as low as 2.5 mg/kg, excess neonatal fatalities are observed (LD 50 is from 5–10 mg/kg). [1]
The PCB oil leaked to rice bran oil consumed by thousands of people in Japan (Yusho disease 1968) and Taiwan (Yu-cheng disease 1979). The toxic effects have been attributed to dioxin-like PCBs and PCDFs. Their daily intake was up to 100,000 times higher than average intake presently. [1]
Similar symptoms and effects of the PCBs and PCDFs were shown, especially in children. [6] There have been studies undertaken on animals to understand the mechanisms of PCBs and PCDFs and their effects. [1] Scientists discovered that low levels of PCBs could kill fish and other wildlife and as such their use in manufacturing was reduced. [7]
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Bioremediation of PCBs is the use of microorganisms to degrade PCBs from contaminated sites, relying on multiple microorganisms' co-metabolism. Anaerobic microorganisms dechlorinate PCBs first, and other microorganisms that are capable of doing BH pathway can break down the dechlorinated PCBs to usable intermediates like acyl-CoA or carbon ...