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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. [4]
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 ...
The human diet accounts for over 95% of the total uptake of TEQ. [12] Risks in humans are typically calculated from known ingestion of contaminants or from blood or adipose tissue samples. However, human intake data is limited, and calculations from blood and tissue are not well supported.
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]
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 ...
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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In 1994, the US EPA reported that dioxins are a probable carcinogen, but noted that non-cancer effects (reproduction and sexual development, immune system) may pose a greater threat to human health. TCDD , the most toxic of the dibenzodioxins, is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC).