Polychlorinated Biphenyls (PCBs)
PCBs are Harmful to Human Health and the Environment
What happens to polychlorinated biphenyls (PCBs) when they enter the environment?
PCBs do not readily break down and thus may remain in the environment for very long periods of time. PCBs can travel long distances in the air and be deposited in areas far away from where they were released. In water, a small amount of PCBs may remain dissolved, but most stick to organic particles and bottom sediments. PCBs also bind strongly to soil. PCBs are taken up by small organisms and fish in water. They are also taken up by other animals that eat these aquatic animals as food. PCBs accumulate in fish and marine mammals, reaching levels that may be many thousands of times higher than in water. PCBs can build up in animals over time and along the food chain. PCBs are found in the fatty tissues of animals living in water or on land, particularly those at the top of the food chain. Thus humans can also accumulate PCBs from the food they eat.
How are humans exposed to PCBs and who is at risk?
Human can be exposed to PCBs by inhaling PCBs polluted air, or direct dermal contact. Diet remains the main source of exposure to PCBs in the general population. Exposure occurs primarily by ingesting high-fat foods contaminated with PCBs; foods such as dairy products, eggs, animal fats and some fish and wildlife are the largest ingested contaminants. Beside ingesting contaminated food and water, many occupations are at risk for exposure. Workers that repair and maintain transformers are exposed to PCBs; this can be from accidents, fires, spills involving PCB transformers and older electrical equipment, and through the disposal of PCB materials. Exposure at work can also occur if you work at a hazardous waste sites where PCBs have been deposited and remain in the soil; or workers in electric cable repair, electroplating, emergency response, firefighting, heat exchanging equipment repair, metal finishing, paving, roofing, pipefitting, plumbing, timber product manufacturing, and waste oil processing. Children can be exposed to contaminated dirt in the playground, school building with old electrical appliance or caulk.
How does PCBs effect human health ?
PCBs are listed as "reasonably anticipated to be human carcinogens" in the Thirteenth Report on Carcinogens published by the National Toxicology Program because they have been linked to increased rates of liver and skin cancers.
Long-term exposure to PCBs may have serious effects on the liver, immune system, endocrine system, reproductive system, and thyroid hormone levels, which in turn may affect normal growth and development. Exposure may damage the nervous system, causing headaches, numbness, weakness, and tingling in the arms and legs; it may also cause learning deficits and changes in activity.
If you are pregnant, exposure to PCBs can cause miscarriage or decreased birth weight in babies. Babies born to and nursed by women exposed to PCBs can have abnormal responses in tests of infant behavior, such as trouble with motor skills and short-term memory loss; immune system problems; and developmental abnormalities.
Short-term exposure to PCBs can irritate and burn the eyes, lungs, nose, and throat. It can cause coughing, difficulty breathing, nausea, vomiting, weight loss, depression, fatigue, sweating at the palms, jaundice, headache, dizziness, nervousness, muscle and joint pain, discoloration of fingernails, arthritis, and stomach pain. In women, short-term exposure can cause irregular menstrual cycles.
Skin contact with PCBs may cause an acne-like skin rash, which can last for years.
Nursing infants, fetuses, and people with liver disorders and skin diseases are most susceptible to the human health effects of PCBs. Drinking alcohol can increase the liver damage caused by PCBs.
Are there test to measure PCB toxicity?
Tests exist to measure levels of PCBs in your blood, body fat, and breast milk, but these are not routinely conducted. Most people normally have low levels of PCBs in their body because nearly everyone has been environmentally exposed to PCBs. The tests can show if your PCB levels are elevated, which would indicate past exposure to above-normal levels of PCBs, but cannot determine when or how long you were exposed or whether you will develop health effects.