The Effects of PCBs

Part of a family of man-made organic chemicals, PCBs (polychlorinated biphenyls) pose a serious threat to human health. Though banned in 1979, according to the Environmental Protection Agency (EPA), PCBs break down very slowly and remain in the environment worldwide. Additional PCBs may also leak from hazardous waste sites or escape due to improper waste handling. Human exposure to PCBs can lead to a variety of conditions affecting most of the major body systems.

Cancer

• Cancer, an abnormal reproduction of cells, tops the EPA's list of possible health effects. The EPA reports that PCBs cause cancer in animals and consider them probable human carcinogens. The National Toxicology Program, the National Institute for Occupational Safety and Health, and the International Agency for Research on Cancer share this position. According to Fox River Watch, the variety of cancers linked to PCB exposure include liver cancer, melanomas (skin cancer), brain cancer and breast cancer. It should be noted that many of the human studies prove inconclusive as a result of small sample size, yet yield similar risk of cancer results as larger studies.

Neurological Effects

• PCBs have links with neurological impairments, such as learning deficits, short-term memory deficits and visual recognition problems. The EPA reports that animal studies using PCBs commonly found in human breast milk produced similar neurological issues as studies with humans.

Immune System Impairment

• The immune system provides the body's main defense against infection, microorganisms and disease. Studies involving rhesus monkeys, which have a similar immune system to human beings, and other animals demonstrated lowered resistance to infection, reduced thymus size and a reduced overall immune response, according to the EPA. The Epstein Barr virus, to which PCBs lower resistance, increases the likelihood of developing non-Hodgkins lymphoma (a type of cancer).

Endocrine Disruption

• The endocrine system plays a major role in hormone production and hormone control in the body. The evidence strongly suggests that PCBs disrupt normal endocrine function, particularly of the thyroid gland, reports the EPA. According to a June 2006 article that appears on the Environmental Health Perspectives website, research conducted at Mount Sinai School of Medicine shows that PCBs directly disrupt endocrine function in mice. Any reduction in normal thyroid function poses a serious problem, as thyroid hormones strongly influence proper growth and development.

Reproductive Effects

• The effects on reproduction following PCB exposure are numerous. The June 2006 article regarding the Mount Sinai research specifically discusses the abnormal development of reproductive organs in mice exposed to PCBs. The documented effects on human beings exposed to PCBs include low birth weight and shorter gestational periods, according to the EPA. Other effects seen in animal studies include lower sperm count, fewer live births and lower conception rates.