Health Effects of PCBs
Studies show that polychlorinated biphenyls or PCBs are definitely pollutants, and they are definitely toxic. Various lab animals exposed to varying levels of PCBs demonstrated adverse health effects, which were fatal at high doses. There are no conclusive study on humans as of yet, but it would be safe to infer that PCB exposure will also have deleterious, possibly carcinogenic, effects.
PCBs are synthetic organic compounds of chlorine and benzene concocted by German scientists in 1881. It served as a coolant for machines and insulation for electrical components. Swann Chemical Company first produced the PCBs in North America in 1929. Monsanto PCBs came into being when Monsanto Company took over production from Swann in 1935, and began selling PCBs under the brand Aroclor in the US. PCBs are persistent in nature, and released in the environment through use and manufacture.
There are 209 types of PCBs and they have various levels of toxicity, apparently dependent on how many chlorine atoms attach to the two benzene rings (biphenyls) in a PCB molecule. The more chlorine atoms, the less soluble it is in water. There are 7 PCB types that were widely used in North America until 1979, when the US Congress halted the production of PCBs.
The issues with PCBs are due mainly to its similarity in structure and toxic modality to dioxins, which are persistent organic pollutants. They get into everything: the soil, the water, and the air. They are very hard to get rid of, and so the risk of exposure is very high. Dioxins and PCBs are absorbed into the fatty tissue of animals, including humans, and affect vital organs.
PCBs are excellent for industrial applications, because they are very stable and resistant to degradation. However, this also makes them very dangerous to humans and the environment in general. Direct exposure is not necessary: a husband can bring it home on his clothes and affect his wife and children; a previously exposed mother can pass the PCBs in her body on to a breastfeeding infant. While there is no definite proof yet that PCBs are harmful to humans, scientists believe that it is only a matter of time before the first toxic exposure victims step forward.