Polychlorinated biphenyls (PCBs) are a group of manufactured organic chemicals that contain 209 individual chlorinated chemicals (known as congeners). Concentrated PCBs are either oily liquids or solids and are colorless to light yellow in color. They have no known smell or taste. There are no known natural sources of PCBs. Some commercial PCB mixtures are known in the United States by their industrial trade name, Aroclor.
PCBs don't burn easily and are good insulating material. They have been used widely as coolants and lubricants in transformers, capacitors, and other electrical equipment. The manufacture of PCBs stopped in the United States in 1977 because of evidence that they build up in the environment and cause harmful health effects. Products containing PCBs are old fluorescent lighting fixtures, electrical appliances containing PCB capacitors, old microscope oil, and hydraulic fluids.
During the time that PCBs were manufactured, there were often no effective controls on disposal. Because they do not break down easily, PCBs are now found widely distributed in our environment. Generally their concentrations in the environment are quite low. However, the chemical properties of PCBs cause them to be concentrated up the food chain.
Fact Sheets relevant to PCBs
How might I be exposed to PCBs?
Because PCBs are no longer manufactured or widely used today, there are relatively few ways that people can be exposed to concentrated PCBs. The most common exposure routes include:
- Food: PCBs in food are probably the single most significant source of exposure for people. PCBs can be highly concentrated in the fish of waters contaminated with even low levels of PCBs. Predator fish at the top of the food chain, as well as bottom feeding fish, tend to contain the highest PCB levels in those waters.
- Surface Soils: At some contamination sites in Wisconsin, PCBs have been found in surface soils at levels that must be cleaned up to prevent a health hazard. The health hazard is related to the potential for people to swallow small amounts of the soil and for the soils to runoff to lakes and rivers and concentrate in fish and other wildlife.
- Drinking Water and Groundwater: PCBs are not very water-soluble so it is quite rare for them to be found in groundwater. Some submersible pumps found in private wells have been recalled because PCB containing oils had been used in their manufacture. When these pumps fail these oils can leak out into the drinking water.
- Indoor Air: Older fluorescent lights found in schools, offices, and homes may still contain transformers or ballasts that contain PCBs. If the ballasts fail, PCBs can leak out and contaminate exposed surfaces and the air.
- In the Workplace: Industrial accidents have been responsible for most cases of acute PCB poisoning in humans. Firefighters and cleanup crews responding to electrical system fires and hazardous waste accidents also may be exposed to PCBs.
How can PCBs affect my and my children's health?
The health effects of PCBs have been very widely studied. PCB related health effects have been studied in people, laboratory animals, and wildlife in contaminated areas. These studies indicate that people who are regularly exposed to PCBs are at greater risk for a variety of health problems. Some of the most important findings are summarized below. Much of this information was taken from a joint assessment of PCB health effects conducted by the Agency for Toxic Substances and Disease Registry (ATSDR) and the U.S. Environmental Protection Agency (EPA). The full report can be found at: http://www.atsdr.cdc.gov/toxprofiles/tp17.pdf
Neurological Development of Children
Investigators report developmental disorders and cognitive deficits in children of mothers who had eaten moderate to high amounts of contaminated fish during the six years preceding the pregnancy and who continued to do so during the pregnancy. Developmental effects include:
- lower birth weight (160–190 grams)
- smaller head circumference (smaller by 0.6 centimeters)
- on average, babies are born earlier
These developmental effects were still evident 5 to 7 months after the infants' births. Neurobehavioral deficits observed include:
- depressed responsiveness
- impaired visual recognition
- poor short-term memory at 7 months of age
At 4 years of age, these children still had the following:
- deficits in weight gain
- depressed responsiveness
- reduced performance on the visual recognition-memory test (i.e., one of the best validated tests for the assessment of human cognitive function).
At eleven years of age, these children were:
three times more likely to have low verbal IQ scores
twice as likely to lag behind at least two years in reading comprehension
have difficulty paying attention
Impairment was also associated with higher concentrations of lead and mercury levels in the children.
Harmful to the Reproductive System
Animal studies show that PCB exposure reduced the birth weight, conception rates and live birth rates of monkeys. Other studies found PCB exposure reduced sperm counts in rats. Children born to women who worked with PCBs in factories showed decreased birth weight and a significant decrease in gestational age with increasing exposure to PCBs.
May Cause Cancer
EPA uses a "weight-of-evidence" approach in evaluating potential cancer-causing (carcinogen) environmental contaminants. EPA evaluates results of individual studies to be viewed in the context of all of the other available studies. Studies show that PCBs cause cancer in animals. The data strongly suggest that PCBs are probable human carcinogens.
Harmful to the Immune System
Studies in animals and humans suggest that long term exposure to PCBs can suppress the immune system.
There has been significant discussion and research on the effects of environmental contaminants on the endocrine system ("endocrine disruption"). PCBs have been demonstrated to exert effects on thyroid hormone levels in animals and humans. Thyroid hormone levels are critical for normal growth and development. Alterations in thyroid hormone levels may have significant implications for health.
How can I limit PCB exposure to myself and child?
Because PCBs are found throughout the environment, they may be nearly impossible to avoid all together. However, steps can be taken to reduce unnecessary exposure:
- Pregnant mothers, women who plan to become pregnant, children and nursing mothers should limit their consumption of sport-caught fish from waters contaminated with PCBs. Follow the Wisconsin fish consumption advisory found at the Department of Natural Resources (DNR) website.
- If you live near a hazardous waste facility, make sure children do not play directly in the soil. Practice good hygiene habits. Wash children's hands and faces after playing and before eating. Do not let them eat the dirt.
- If any member of the household works with old electrical equipment including transformers, be sure that the equipment is properly maintained and the area is well ventilated.
What health concerns exist for pregnant women or women planning to become pregnant?
Research shows that the unborn child is vulnerable to brain damage during pregnancy. Chemicals such as PCBs, tobacco smoke and alcohol can weaken or damage the brain development process. The effects of exposure to these chemicals can become evident years later as learning disabilities, attention deficit disorders, mental retardation or personality and behavior difficulties.
PCBs are stored in the body for long periods of time. Maternal exposure occurring prior to pregnancy can contribute to the overall body burden and result in exposure to the developing fetus.
I’ve eaten fish containing PCBs, should I breastfeed my baby?
In addition to the nutrient value of breast milk, nursing gives infants other benefits, such as factors that boost immunity and emotional closeness to the mother. In general, these benefits outweigh the risk that contaminants in your milk will harm your baby. Follow your state and federal guidelines on what type and amount of fish is safe to eat if you are nursing. If you are concerned that you may have a high body burden of PCBs, try not to lose weight during the time that you are nursing. PCBs may be released into the milk as fat is broken down.
Can a medical test show PCB exposure?
Talk to your health care provider if you have concerns about PCB exposure. In general, testing to estimate your body burden of chemical contaminants (such as PCBs) is very expensive, and few clinical laboratories are capable of accurately performing such analysis. Moreover, no treatments are available for reducing high body burdens of chemicals, such as PCBs. Most importantly, you should follow the guidelines for minimizing exposure. However, the following tests can detect PCB presence in the body:
- Blood tests can detect recent exposures to large amounts of PCBs
- Other tests can detect PCBs in body fat and breast milk
What would the blood test tell me?
- Almost all of us will have some PCBs in our bodies. Blood tests can show if you have been exposed to higher-than-normal amounts of PCBs.
- It cannot determine the exact amount or type of PCBs you have been exposed to or how long you’ve been exposed.
- It cannot predict whether you will experience harmful health effects.
Can I swim in water with PCBs in it?
Having a PCB related fish consumption advisory on a body of water is not necessarily an indication that it is not safe to wade or swim in those waters. If you have a question about a particular body of water, contact your local health department.
Which fish are safe to eat?
In general, eat smaller, younger fish. Small organisms absorb contaminants in the water, and are in turn eaten by small fish. Big fish eat the small fish, and in this way, the contaminants accumulate up the food chain. The top level predators such as walleye and bass contain the highest amounts of contaminants. Since PCBs are stored in fat, smaller, leaner, shorter-lived species such as bluegills, crappie and yellow perch contain very low or undetectable levels of PCBs.
Great Lakes fish and fish from the Mississippi River are more likely to contain PCBs than fish from Wisconsin inland lakes and rivers.
Where can I go for more information?
EPA Websites on Exposure to PCBs
- Wisconsin Department of Health Services, Environmental Health Resources
- ATSDR compilation of PCB health studies
- Neurobehavioral Health Effects of Exposure to PCBs (PDF, 59 KB)
- PCB Exposure in Children
- Environmental effects on neurodevelopment of children
Fish Consumption Advisories for Wisconsin
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