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Polychlorinated Biphenyls (PCBs)Public Health Statement for Polychlorinated Biphenyls, PCBs Toxicology, and PCBs MSDS InformationThis public health statement tells you about polychlorinated biphenyls (PCBs) and the effects of exposure. Learn why PCB is in our blood and what effects of exposure to it are.
The Environmental Protection Agency (EPA) identifies the most serious hazardous waste sites in the nation. These sites make up the National Priorities List (NPL) and are the sites targeted for long-term federal cleanup activities. PCBs have been found in at least 500 of the 1,598 current or former NPL sites. However, the total number of NPL sites evaluated for PCBs is not known. As more sites are evaluated, the sites at which PCBs are found may increase. This information is important because exposure to PCBs may harm you and because these sites may be sources of exposure. When a substance is released from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment. This release does not always lead to exposure. You are exposed to a substance only when you come in contact with it. You may be exposed by breathing, eating, or drinking the substance, or by skin contact. If you are exposed to PCBs, many factors determine whether you'll be harmed. These factors include the dose (how much), the duration (how long), and how you come in contact with them. You must also consider the other chemicals you're exposed to and your age, sex, diet, family traits, lifestyle, and state of health.
What are polychlorinated biphenyls (PCBs)?PCBs are a group of synthetic organic chemicals that can cause a number of different harmful effects. There are no known natural sources of PCBs in the environment. PCBs are either oily liquids or solids and are colorless to light yellow. Some PCBs are volatile and may exist as a vapor in air. They have no known smell or taste. PCBs enter the environment as mixtures containing a variety of individual chlorinated biphenyl components, known as congeners, as well as impurities. Because the health effects of environmental mixtures of PCBs are difficult to evaluate, most of the information in this toxicological profile is about seven types of PCB mixtures that were commercially produced. These seven kinds of PCB mixtures include 35% of all the PCBs commercially produced and 98% of PCBs sold in the United States since 1970. Some commercial PCB mixtures are known in the United States by their industrial trade name, Aroclor. For example, the name Aroclor 1254 means that the mixture contains approximately 54% chlorine by weight, as indicated by the second two digits in the name. Because they don't burn easily and are good insulating materials, PCBs were used widely as coolants and lubricants in transformers, capacitors, and other electrical equipment. The manufacture of PCBs stopped in the United States in August 1977 because there was evidence that PCBs build up in the environment and may cause harmful effects. Consumer products that may contain PCBs include old fluorescent lighting fixtures, electrical devices or appliances containing PCB capacitors made before PCB use was stopped, old microscope oil, and old hydraulic oil. You can find further information on the physical properties and uses of PCBs in Chapters 4 and 5 of the toxicological profile.
back to top What happens to polychlorinated biphenyls (PCBs) when they enter the environment?Before 1977, PCBs entered the air, water, and soil during their manufacture and use in the United States. Wastes that contained PCBs were generated at that time, and these wastes were often placed in landfills. PCBs also entered the environment from accidental spills and leaks during the transport of the chemicals, or from leaks or fires in transformers, capacitors, or other products containing PCBs. Today, PCBs can still be released into the environment from poorly maintained hazardous waste sites that contain PCBs; illegal or improper dumping of PCB wastes, such as old transformer fluids; leaks or releases from electrical transformers containing PCBs; and disposal of PCB-containing consumer products into municipal or other landfills not designed to handle hazardous waste. PCBs may be released into the environment by the burning of some wastes in municipal and industrial incinerators. Once in the environment, PCBs do not readily break down and therefore may remain for very long periods of time. They can easily cycle between air, water, and soil. For example, PCBs can enter the air by evaporation from both soil and water. In air, PCBs can be carried long distances and have been found in snow and sea water in areas far away from where they were released into the environment, such as in the arctic. As a consequence, PCBs are found all over the world. In general, the lighter the type of PCBs, the further they may be transported from the source of contamination. PCBs are present as solid particles or as a vapor in the atmosphere. They will eventually return to land and water by settling as dust or in rain and snow. In water, PCBs may be transported by currents, attach to bottom sediment or particles in the water, and evaporate into air. Heavy kinds of PCBs are more likely to settle into sediments while lighter PCBs are more likely to evaporate to air. Sediments that contain PCBs can also release the PCBs into the surrounding water. PCBs stick strongly to soil and will not usually be carried deep into the soil with rainwater. They do not readily break down in soil and may stay in the soil for months or years; generally, the more chlorine atoms that the PCBs contain, the more slowly they break down. Evaporation appears to be an important way by which the lighter PCBs leave soil. As a gas, PCBs can accumulate in the leaves and above-ground parts of plants and food crops. PCBs are taken up into the bodies of small organisms and fish in water. They are also taken up by other animals that eat these aquatic animals as food. PCBs especially accumulate in fish and marine mammals (such as seals and whales) reaching levels that may be many thousands of times higher than in water. PCB levels are highest in animals high up in the food chain. You can find more information about what happens to PCBs in the environment such as via aerobic and anaerobic degradation of polychlorinated biphenyls below. back to topHow might I be exposed to polychlorinated biphenyls (PCBs)?Although PCBs are no longer made in the United States, people can still be exposed to them. Many older transformers and capacitors may still contain PCBs, and this equipment can be used for 30 years or more. Old fluorescent lighting fixtures and old electrical devices and appliances, such as television sets and refrigerators, therefore may contain PCBs if they were made before PCB use was stopped. When these electric devices get hot during operation, small amounts of PCBs may get into the air and raise the level of PCBs in indoor air. Because devices that contain PCBs can leak with age, they could also be a source of skin exposure to PCBs. Small amounts of PCBs can be found in almost all outdoor and indoor air, soil, sediments, surface water, and animals. However, PCB levels have generally decreased since PCB production stopped in 1977. People are exposed to PCBs primarily from contaminated food and breathing contaminated air. The major dietary sources of PCBs are fish (especially sportfish that were caught in contaminated lakes or rivers), meat, and dairy products. Between 1978 and 1991, the estimated daily intake of PCBs in adults from dietary sources declined from about 1.9 nanograms (a nanogram is a billionth part of a gram) to less than 0.7 nanograms. PCB levels in sportfish are still high enough so that eating PCB-contaminated fish may be an important source of exposure for some people. Recent studies on fish indicate maximum concentrations of PCBs are a few parts of PCBs in a million parts (ppm) of fish, with higher levels found in bottom-feeders such as carp. Meat and dairy products are other important sources of PCBs in food, with PCB levels in meat and dairy products usually ranging from less than 1 part in a billion parts (ppb) of food to a few ppb. Concentrations of PCBs in subsurface soil at a Superfund site have been as high as 750 ppm. People who live near hazardous waste sites may be exposed to PCBs by consuming PCB-contaminated sportfish and game animals, by breathing PCBs in air, or by drinking PCB-contaminated well water. Adults and children may come into contact with PCBs when swimming in contaminated water and by accidentally swallowing water during swimming. However, both of these exposures are far less serious than exposures from ingesting PCB-contaminated food (particularly sportfish and wildlife) or from breathing PCB-contaminated air. Workplace exposure to PCBs can occur during repair and maintenance of PCB transformers; accidents, fires, or spills involving PCB transformers and older computers and instruments; and disposal of PCB materials. In addition to older electrical instruments and fluorescent lights that contain PCB-filled capacitors, caulking materials, elastic sealants, and heat insulation have also been known to contain PCBs. Contact with PCBs at hazardous waste sites can happen when workers breathe air and touch soil containing PCBs. Exposure in the contaminated workplace occurs mostly by breathing air containing PCBs and by touching substances that contain PCBs. You can find more information about exposure to PCBs in Chapter 6 of the toxicological profile. back to topHow can polychlorinated biphenyls (PCBs) enter and leave my body?If you breathe air that contains PCBs, they can enter your body through your lungs and pass into the bloodstream. We do not know how fast or how much of the PCBs that are breathed will pass into the blood. A common way for PCBs to enter your body is by eating meat or fish products or other foods that contain PCBs. Exposure from drinking water is less than from food. It is also possible that PCBs can enter your body by breathing indoor air or by skin contact in buildings that have the kinds of old electrical devices that contain and can leak PCBs. For people living near waste sites or processing or storage facilities, and for people who work with or around PCBs, the most likely ways that PCBs will enter their bodies are from skin contact with contaminated soil and from breathing PCB vapors. Once PCBs are in your body, some may be changed by your body into other related chemicals called metabolites. Some metabolites of PCBs may have the potential to be as harmful as some unchanged PCBs. Some of the metabolites may leave your body in the feces in a few days, but others may remain in your body fat for months. Unchanged PCBs may also remain in your body and be stored for years mainly in the fat and liver, but smaller amounts can be found in other organs as well. PCBs collect in milk fat and can enter the bodies of infants through breast-feeding. For more information on how PCBs can enter and leave your body, see Chapter 3 of the toxicological profile. back to topHow can polychlorinated biphenyls (PCBs) affect my health?Many studies have looked at how PCBs can affect human health. Some of these studies investigated people exposed in the workplace, and others have examined members of the general population. Skin conditions, such as acne and rashes, may occur in people exposed to high levels of PCBs. These effects on the skin are well documented, but are not likely to result from exposures in the general population. Most of the human studies have many shortcomings, which make it difficult for scientists to establish a clear association between PCB exposure levels and health effects. Some studies in workers suggest that exposure to PCBs may also cause irritation of the nose and lungs, gastrointestinal discomfort, changes in the blood and liver, and depression and fatigue. Workplace concentrations of PCBs, such as those in areas where PCB transformers are repaired and maintained, are higher than levels in other places, such as air in buildings that have electrical devices containing PCBs or in outdoor air, including air at hazardous waste sites. Most of the studies of health effects of PCBs in the general population examined children of mothers who were exposed to PCBs. The possible health effects of PCBs in children are discussed in Section 1.6. To protect the public from the harmful effects of toxic chemicals and to find ways to treat people who have been harmed, scientists use many tests. One way to see if a chemical will hurt people is to learn how the chemical is absorbed, used, and released by the body; for some chemicals, animal testing may be necessary. Animal testing may also be used to identify health effects such as cancer or birth defects. Without laboratory animals, scientists would lose a basic method to get information needed to make wise decisions to protect public health. Scientists have the responsibility to treat research animals with care and compassion. Laws today protect the welfare of research animals, and scientists must comply with strict animal care guidelines. Rats that ate food containing large amounts of PCBs for short periods of time had mild liver damage, and some died. Rats, mice, or monkeys that ate smaller amounts of PCBs in food over several weeks or months developed various kinds of health effects, including anemia, acne-like skin conditions, and liver, stomach, and thyroid gland injuries. Other effects caused by PCBs in animals include reductions in the immune system function, behavioral alterations, and impaired reproduction. Some PCBs can mimic or block the action of hormones from the thyroid and other endocrine glands. Because hormones influence the normal functioning of many organs, some of the effects of PCBs may result from endocrine changes. PCBs are not known to cause birth defects. Only a small amount of information exists on health effects in animals exposed to PCBs by skin contact or breathing. This information indicates that liver, kidney, and skin damage occurred in rabbits following repeated skin exposures, and that a single exposure to a large amount of PCBs on the skin caused death in rabbits and mice. Breathing PCBs over several months also caused liver and kidney damage in rats and other animals, but the levels necessary to produce these effects were very high. For more information on how PCBs can affect your health, see Chapters 2 and 3 of the toxicological profile. Studies of workers provide evidence that PCBs were associated with certain types of cancer in humans, such as cancer of the liver and biliary tract. Rats that ate commercial PCB mixtures throughout their lives developed liver cancer. Based on the evidence for cancer in animals, the Department of Health and Human Services (DHHS) has stated that PCBs may reasonably be anticipated to be carcinogens. Both EPA and the International Agency for Research on Cancer (IARC) have determined that PCBs are probably carcinogenic to humans. back to topHow can polychlorinated biphenyls (PCBs) affect children?This section discusses potential health effects from exposures during the period from conception to maturity at 18 years of age in humans. Children are exposed to PCBs in the same way as are adults: by eating contaminated food, breathing indoor air in buildings that have electrical devices containing PCBs, and drinking contaminated water. Because of their smaller weight, children’s intake of PCBs per kilogram of body weight may be greater than that of adults. In addition, a child’s diet often differs from that of adults. A Food and Drug Administration (FDA) study in 1991 estimated dietary intakes of PCBs for infants (6 months) and toddlers (2 years) of less than 0.001 and 0.002 µg/kg/day. Children who live near hazardous waste sites may accidentally eat some PCBs through hand-to-mouth behavior, such as by putting dirty hands or other soil/dirt covered objects in their mouths, or eating without washing their hands. Some children also eat dirt on purpose; this behavior is called pica. Children could also be exposed by playing with old appliances or electrical devices that contain PCBs. It is possible that children could be exposed to PCBs following transport of the chemical on clothing from the parent’s workplace to the home. House dust in homes of workers exposed to PCBs contained higher than average levels of PCBs. PCBs have also been found on the clothing of firefighters following transformer fires. The most likely way infants will be exposed is from breast milk that contains PCBs. Fetuses in the womb are also exposed from the exposed mother. In one study of women exposed to relatively high concentrations of PCBs in the workplace during pregnancy, their babies weighed slightly less at birth than babies born to women exposed to lower concentrations of PCBs. Studies of women who consumed high amounts of fish contaminated with PCBs and other chemicals also had babies that weighed less than babies from women who did not eat fish. Similar observations have been made in some studies of women with no known high exposure to PCBs, but not all studies have confirmed these findings. Babies born to women who ate fish contaminated with PCBs before and during pregnancy showed abnormal responses to tests of infant behavior. Some of these behaviors, such as problems with motor skills and a decrease in short-term memory, persisted for several years. However, in these studies, the women may have been exposed to other chemicals. Other studies suggest that the immune system may be affected in children born to and nursed by mothers exposed to increased levels of PCBs. There are no reports of structural birth defects in humans caused by exposure to PCBs or of health effects of PCBs in older children. It is not known whether PCB exposure can cause in skin acne and rashes in children as occurs in some adults, although it is likely that the same effects would occur at very high PCB exposure levels. Animal studies have shown harmful effects in the behavior of very young animals when their mothers were exposed to PCBs and they were exposed in the womb or by nursing. In addition, some animal studies suggest that exposure to PCBs causes an increased incidence of prenatal death and changes in the immune system, thyroid, and reproductive organs. Studies in monkeys showed that young animals developed skin effects from nursing after their mothers were exposed to PCBs. Some studies indicate that very high doses of PCBs may cause structural birth defects in animals. Children can be exposed to PCBs both prenatally and from breast milk. PCBs are stored in the mother’s body and can be released during pregnancy, cross the placenta, and enter fetal tissues. Because PCBs dissolve readily in fat, they can accumulate in breast milk fat and be transferred to babies and young children. PCBs have been measured in umbilical cord blood and in breast milk. Some studies have estimated that an infant who is breast fed for 6 months may accumulate in this period 6–12% of the total PCBs that will accumulate during its lifetime. However, in most cases, the benefits of breast-feeding outweigh any risks from exposure to PCBs in mother’s milk. You should consult your health care provider if you have any concerns about PCBs and breast feeding. Because the brain, nervous system, immune system, thyroid, and reproductive organs are still developing in the fetus and child, the effects of PCBs on these target systems may be more profound after exposure during the prenatal and neonatal periods, making fetuses and children more susceptible to PCBs than adults. More information regarding children’s health and PCBs can be found in Chapter 3 (Section 3.7) of the toxicological profile. back to topHow can families reduce their risk of expsoure to Polychlorinated biphenyls (PCBs)?If your doctor finds that you have been exposed to significant amounts of polychlorinated biphenyls, ask whether your children might also be exposed. Your doctor might need to ask your state health department to investigate. You and your children may be exposed to PCBs by eating fish or wildlife caught from contaminated locations. Certain states, Native American tribes, and U.S. territories have issued fish and wildlife advisories to warn people about PCB-contaminated fish and fish-eating wildlife. These advisories will tell you what types and sizes of fish and game animals are of concern. An advisory may completely ban eating fish or game or tell you to limit your meals of a certain fish or game type. For example, an advisory may tell you not to eat a certain type of fish or game more than once a month. The advisory may tell you only to eat certain parts of the fish or game and how to prepare or cook the fish or game to decrease your exposure to PCBs. The fish or wildlife advisory may have special restrictions to protect pregnant women, nursing mothers, and young children. To reduce your children’s exposure to PCBs, obey these advisories. Additional information on fish and wildlife advisories for PCBs, including states that have advisories, is provided in Chapter 6 (Section 6.7) and Chapter 8 of the toxicological profile. You can consult your local and state health departments or state natural resources department on how to obtain PCB advisories, as well as other important information, such as types of fish and wildlife and the locations that the advisories apply to. Children should be told that they should not play with old appliances, electrical equipment, or transformers, since they may contain PCBs. Children who live near hazardous waste sites should be discouraged from playing in the dirt near these sites and should not play in areas where there was a transformer fire. In addition, children should be discouraged from eating dirt, and careful handwashing practices should be followed. As mentioned in Section 1.3 of the profile, workplace exposure to PCBs can still occur during repair and maintenance of old PCB transformers; accidents, fires, or spills involving these transformers or other PCB-containing items; and disposal of PCB materials. If you are exposed to PCBs in the workplace, it may be possible to carry them home from work. Your occupational health and safety officer at work can tell you whether the chemicals you work with may contain PCBs and are likely to be carried home on your clothes, body, or tools. If this is the case, you should shower and change clothing before leaving work, and your work clothes should be kept separate from other clothes and laundered separately. back to topIs there a medical test to determine whether I have been exposed to polychlorinated biphenyls (PCBs)?Levels of PCBs in the environment were zero before PCBs were manufactured. Now, all people in industrial countries have some PCBs in their bodies. There are tests to determine whether PCBs are in the blood, body fat, and breast milk. These are not regular or routine clinical tests, such as the one for cholesterol, but could be ordered by a doctor to detect PCBs in people exposed to them in the environment and at work. If your PCB levels are higher than the background levels, this will show that you have been exposed to high levels of PCBs. However, these measurements cannot determine the exact amount or type of PCBs that you have been exposed to, or how long you have been exposed. Although these tests can indicate whether you have been exposed to PCBs to a greater extent than the general population, they do not predict whether you will develop harmful health effects. Blood tests are the easiest, safest, and probably the best method for detecting recent exposures to large amounts of PCBs. Results of such tests should be reviewed and carefully interpreted by physicians with a background in environmental and occupational medicine. Nearly everyone has been exposed to PCBs because they are found throughout the environment, and people are likely to have detectable amounts of PCBs in their blood, fat, and breast milk. Recent studies have shown that PCB levels in tissues from United States population are now declining. Additional information on tests used to determine whether you have been exposed to PCBs can be found in Chapter 3 (Section 3.11) and Chapter 7 (Section 7.1) of the toxicological profile. back to topWhat recommendations has the federal government made to protect human health?The federal government develops regulations and recommendations to protect public health . Regulations can be enforced by law. Federal agencies that develop regulations for toxic substances include the Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA), and the Food and Drug Administration (FDA). Recommendations provide valuable guidelines to protect public health but cannot be enforced by law. Federal organizations that develop recommendations for toxic substances include the Agency for Toxic Substances and Disease Registry (ATSDR) and the National Institute for Occupational Safety and Health (NIOSH). Regulations and recommendations can be expressed in not-to-exceed levels in air, water, soil, or food that are usually based on levels that affect animals; then they are adjusted to help protect people. Sometimes these not-to-exceed levels differ among federal organizations because of different exposure times (an 8-hour workday or a 24-hour day), the use of different animal studies, or other factors. Recommendations and regulations are periodically updated as more information becomes available. For the most current information, check with the federal agency or organization that provides it. Some regulations and recommendations for PCBs include the following: The EPA standard for PCBs in drinking water is 0.5 parts of PCBs per billion parts (ppb) of water. For the protection of human health from the possible effects of drinking the water or eating the fish or shellfish from lakes and streams that are contaminated with PCBs, the EPA regulates that the level of PCBs in these waters be no greater than 0.17 parts of PCBs per trillion parts (ppt) of water. States with fish and wildlife consumption advisories for PCBs are identified in Chapter 6 (Section 6.7) and Chapter 8 of the toxicological profile. The FDA has set residue limits for PCBs in various foods to protect from harmful health effects. FDA required limits include 0.2 parts of PCBs per million parts (ppm) in infant and junior foods, 0.3 ppm in eggs, 1.5 ppm in milk and other dairy products (fat basis), 2 ppm in fish and shellfish (edible portions), and 3 ppm in poultry and red meat (fat basis). OSHA regulates that workers not be exposed by inhalation over a period of 8 hours for 5 days per week to more than 1 milligram per cubic meter of air (mg/m³) for 42% chlorine PCBs, or to 0.5 mg/m³ for 54% chlorine PCBs. NIOSH recommends that workers not breathe air containing 42 or 54% chlorine PCB levels higher than 1 microgram per cubic meter of air (µg/m³) for a 10-hour workday, 40-hour workweek. EPA requires that companies that transport, store, or dispose of PCBs follow the rules and regulations of the federal hazardous waste management program. EPA also limits the amount of PCBs put into publicly owned waste water treatment plants. To minimize exposure of people to PCBs, EPA requires that industry tell the National Response Center each time 1 pound or more of PCBs have been released to the environment. For more information on federal and state regulations and guidelines for PCBs, see Chapter 8 of the toxicological profile. back to topWhat are other names for polychlorinated biphenyls?
What are the common uses of PCBs?
What happens when PCBs enter the environment?PCBs do not readily break down in the environment and therefore may persist for a very long time. They can easily cycle between air, water, and soil.
What are the sources, routes, and types of exposure to PCBs?
What are the effects of exposure to PCBs?
What are the safety guidelines for exposure to PCBs?
What are the minimal risk levels for exposure to PCBs?An MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse non-cancer health effects over a specified duration of exposure. Below is a comparison of pcb exposure routes
What are the most important or common mediating factors?The factors that determine how severe the health effects are exposure to PCBs include:
How is exposure to PCBs managed and treated?No specific treatment for PCB toxicity is currently available. However, decontamination and supportive treatment are advised.
How does the body eliminate PCBs?
Is there a test to see if my child or I have been exposed to PCBs?There are tests to determine whether PCBs are in the blood, body fat, and breast milk. These are not regular or routine clinical tests, such as the one for cholesterol, but could be ordered by a doctor to detect PCBs in people exposed to them in the environment and at work.
Current research needs
Where can I get more information?ATSDR. Toxicological Profile for Polychlorinated Biphenyls. Atlanta: Agency for Toxic Substances and Disease Registry, 2000 November. Available at: www.atsdr.cdc.gov/toxprofiles/tp17.html. ATSDR, Substance Specific Priority Data Needs, Atlanta: Agency for Toxic Substances and Disease Registry, 2006 March. Available at: www.atsdr.cdc.gov/pdns/index.html. EPA. Polychlorinated Biphenyls Home Page. Washington, DC: Environmental Protection Agency. 2006 February 15. Available at: www.epa.gov/opptintr/pcb/. EPA. Technical factsheet on polychlorinated biphenyls. Washington, DC: Environmental Protection Agency. 2006 February 21. Available at: www.epa.gov/safewater/dwh/t-soc/pcbs.html. CDC. Third national report on human exposure to environmental chemicals. Atlanta: Centers for Disease Control and Prevention. 2005 July 21. Available at: www.cdc.gov/exposurereport/. back to topReferencesAgency for Toxic Substances and Disease Registry (ATSDR). 2000. Toxicological profile for polychlorinated biphenyls (PCBs). Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. back to top
Complete PCB Toxicological Information
POLYCHLORINATED BIPHENYLS Human Health Effects:
Evidence for Carcinogenicity:
Classification of carcinogenicity: 1) evidence in humans: limited; 2) evidence in animals: sufficient. Overall summary evaluation of carcinogenic risk to humans is Group 2A: The agent is probably carcinogenic to humans. /Polychlorinated biphenyls; from table/
CLASSIFICATION: B2; probable human carcinogen. BASIS FOR CLASSIFICATION: A 1996 study found liver tumors in female rats exposed to Aroclors 1260, 1254, 1242 and 1016 and in male rats exposed to 1260. These mixtures contain overlapping groups of congeners that, together, span the range of congeners most often found in environmental mixtures. Earlier studies found high, statistically significant incidences of liver tumors in rats ingesting Aroclor 1260 or Clophen A 60 (Kimbrough et. al., 1975; Norback and Weltman, 1985; Schaeffer et. al., 1984). Mechanistic studies are beginning to identify several congeners that have dioxin-like activity and may promote tumors by different modes of action. PCBs are absorbed through ingestion, inhalation, and dermal exposure, after which they are transported similarly through the circulation. This provides a reasonable basis for expecting similar internal effects from different routes of environmental exposure. Information on relative absorption rates suggests that differences in toxicity across exposure routes are small. The human studies are being updated; currently available evidence is inadequate, but suggestive. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Sufficient.
Human Toxicity Excerpts:
IN SURVEY OF 3 GROUPS OF WORKERS EXPOSED TO POLYCHLORINATED BIPHENYLS (PCBS) SERUM PCB CONCN WERE QUANTITATED AS LOWER PCB & HIGHER PCB. SERUM LOWER PCB & HIGHER PCB CONCN WERE MANY TIMES GREATER AMONG WORKERS EMPLOYED IN POWER CAPACITOR MANUFACTURING THAN AMONG GENERAL POPULATION. POSITIVE CORRELATIONS OF SYMPTOMS SUGGESTIVE OF MUCOUS MEMBRANE & SKIN IRRITATION, MALAISE & ALTERED SENSATION WERE NOTED WITH INCR CONCN OF SERUM PCB. NO CLINICAL ABNORMALITIES ATTRIBUTABLE TO EXPOSURE TO PCB WERE OBSERVED. SERUM CONCN WERE POSITIVELY CORRELATED WITH INCR OF GLUTAMIC-OXALACETIC TRANSAMINASE, SERUM GAMMA-GLUTAMYL TRANSPEPTIDASE & PLASMA TRIGLYCERIDE, & INVERSELY CORRELATED WITH PLASMA HIGH DENSITY LIPOPROTEIN-CHOLESTEROL.
Deaths that occurred up to 5 1/2 yr after first exposure to PCB's ... were reported. Nine (41%) of 22 deaths were due to malignant neoplasms. Three of the tumors occurred in the stomach, one in the liver, two in the lung and one in the breast, and two were malignant lymphomas.
A significant correlation was found between plasma levels of polychlorinated biphenyls(PCBs) in mothers occupationally exposed to these cmpd and the PCB milk levels. It has been observed that if these mothers nursed their babies for more than three months, the PCB levels in the infants exceeded that of their mothers. These cmpd were subsequently retained in the children for many years. ...
/RESPONSES TO PCBS/: ACNE; HYPERPIGMENTATION OF SKIN; HYPERACTIVE MEIBOMIAN GLANDS; CONJUNCTIVITIS; EDEMA OF EYELIDS; SUBCUTANEOUS EDEMA; KERATIN CYSTS IN HAIR FOLLICLES; HYPERPLASIA OF HAIR FOLLICLE EPITHELIUM; HEPATIC HYPERTROPHY; DECR NUMBER OF RED BLOOD CELLS; DECR HEMOGLOBIN; SERUM HYPERLIPIDEMIA; LEUCOCYTOSIS. Disease/Syndrome Chloracne Category Skin Disease Acute/Chronic Chronic Biomedical References Search PubMed Comments Chloracne appears as comedones and straw-colored cysts on the face. Cysts may also occur in the axillae and groin. The condition usually appears within 2 months of exposure and resolves within 4-6 months after cessation of exposure. Chloracne is associated with dry skin, conjunctivitis, scarring, peripheral neuropathy, and liver abnormalities. Chemicals that can cause chloracne include: dioxin, pentachlorophenol, PCBs, PBBs, furans, polyhalogenated naphthalenes (polychloronaphthalenes), DDT (crude trichlorobenzene), Propanil, Methazole (both tetrachloroazoxybenzenes), 1,2,3,4-Tetrachlorobenzene, and Dichlobenil. [Rosenstock, p. 714-5] Acneform lesions may appear as early as 1 to 3 weeks after dioxin exposure. Most cases of chloracne resolve within 1 to 3 years. There is no acceptable dose-response model for chloracne in exposed human populations. Chloracne may develop weeks or months after exposure and may be dependent upon individual predisposition. [ATSDR Case Studies: PCB Toxicity] Latency/Incubation Weeks to months Diagnostic Clinical ICD-9 Code 706.1 Reference Link CCOHS - Occupational Acne Image Chloracne. DermNet NZ Related Information in Haz-Map Symptoms/Findings Symptoms/Findings associated with this disease: acne pustule Job Tasks High risk job tasks associated with this disease: Remove or replace PCB contaminated fluid in transformers Work in confined space Work with toxic chemicals that could be spilled or released Agents Hazardous agents that cause this disease: Dermatotoxins that cause chloracne
A leaking heat exchanger in a chemical plant discharged polychlorinated biphenyl (PCB) vapors. No employees worked routinely at the point of leakage, but breathing zone levels in work areas were found to be 0.1 mg/cu m. The period of exposure was 19 months. Seven of 14 exposed workers developed mild to moderate chloracne after exposure durations of 5-14 months. Liver function tests showed normal serum bilirubin, 24 and 48 hr cephalin flocculations, thymol turbidities, and serum alkaline phosphatase activities in six of the seven workers, but borderline increases in cephalin flocculation and thymol turbidity in the seventh. After 13 months, the thymol turbidity but not the cephalin flocculation had improved.
An analysis of the health effects of polychlorinated biphenyls (PCB) on eight laboratory workers involved in testing dielectric fluids was made. ... The workers, all males 25 to 49 yr of age, had been employed 2.5 to 18 yrs. Breathing zone, point source, and general work area samples were collected on three separate occasions. The ranges were: breathing zone, 0.014 to 0.073 mg/cu m; point source (near an oven), 0.042 to 0.264 mg/cu m; and room area, 0.013 to 0.15 mg/cu m. Blood concns were 36 to 286 ppb which is substantially above the range in several studies of general populations. Workers complained of dry, sore throat (6/8), skin rash (3/8), gastrointestinal disturbances (3/8), and eye irritation and headache (2/8). Examination disclosed one patient with skin rash, two with nasal irritation, one showing rales, and four with high blood pressure, but no abnormalities in liver function.
Irregular menstrual cycles, early abortions and the birth of small, hyperpigmented and hyperkeratotic infants have been observed.
Spirometric findings in a retrospective cohort of 136 capacitor workers with occupational exposure to polychlorinated biphenyls (PCBs) during active use (1976) and after the PCB ban (1979 and 1983) are reported. Quantitative exposure levels are not known. Subjects were categorized as having high, medium, or low exposure depending primarily on the extent of dermal contact. Mean 1979 serum PCB levels were elevated 35 to 40 times the normal level. Duration of employment ranged from 1-35 yr. Obstructive impairment was consistently found in 15% of the workers in 1976 and 1979. A history of respiratory illness and reduced FEV 1/FVC was correlated in a dose-response fashion with PCB exposure category and serum PCB levels in females in 1976 but the association disappeared in 1979. It is not clear whether the association held when controlled for smoking. There was no association between PCB exposure and abnormal pulmonary function tests in males.
PCBS ARE LIVER TOXINS & CAUSE CHLORACNE & POSSIBLY PERIPHERAL NEUROPATHY IN MAN.
The first documentation of human effects as a result of ingestion of PCBs was derived from the Japanese poisoning incident that occurred in 1968. The victims suffered an acute toxicosis from consuming rice oil contaminated with an industrial oil, Kanechlor-400, consisting of a mixture of polychlorinated biphenyls (PCB), polychlorinated dibenzofurans (PCDF), and polychlorinated quinones (PCQ). The average total amount of PCBs consumed was estimated to be approximately 2 g, with approximately 0.5 g being the least total amount consumed by an affected group of some 325 people at the time. ... The most notable symptoms of Yusho among 189 patients included dark brown pigmentation of nails and skin, follicular accentuation, acneform eruptions, increased eye discharge, increased sweating at the palms and feeling of weakness. ...
A mass outbreak of a peculiar skin disease /including pigmentation and acne from eruptions/ was recorded in Taichung and Changwa in Central Taiwan. The cause of the disease was later identified to be the ingestion of rice bran oil contaminated with polychlorinated biphenyls (PCBs), and there were > 1900 victims. Blood PCB levels of 66 affected persons ranged from 11-720 ppb (mean 49 ppb) at approx 9-12 months after consumption of the PCB-contaminated oil.
Polychlorinated biphenyl blood residues were measured in 29 infertile males and in 14 matched control subjects at a hospital in Jerusalem, Israel. The patients' ages ranged from 25 to 45 years. The patients exhibited one or more impaired semen characteristics such as decreased spermatozoa count, lower sperm motility, or a greater proportion of morphologically abnormal spermatozoa. The control group, matched by age and smoking habits, consisted of randomly selected patients with minor illnesses. Each of them had at least one child not older than two years of age. None of the subjects had a history of occupational exposure to organochlorine compounds. The polychlorinated biphenyl levels were measured by GC-ECD. The mean concentration of total polychlorinated biphenyls in the infertile patients was 11.21 + or - 13.48 ng/g blood serum (range 0 to 64.2 ng/g). The control subjects had a mean concentration of 7.94 + or - 14.69 ng/g (range 0 to 47.3 ng/g).
A retrospective cohort mortality study of workers exposed to polychlorinated biphenyl (PCBs) in two plants manufacturing electrical capacitors was reported in 1981. The study was conducted primarily to examine the risk of cancer mortality associated with exposure to PCBs: due to the availability of animal data, liver cancer was the disease of most interest. Because of the small number of deaths and a relatively short observation period the study was inconclusive. Therefore, the study was updated by adding 7 yr of observation increasing the number of deaths in the study cohort from 163 to 295. Mortality from all causes was found to be lower than expected (295 observed versus 318 expected deaths) as well as mortality from all cancers (62 observed versus 80 expected deaths). A statistically significant excess in deaths was observed in the category that includes cancer of the liver (primary and unspecified), gall bladder, and biliary tract (5 observed versus 1.9 expected; p< 0.05). Most of this excess was observed in women employed in one plant.
The possibility of polychlorinated biphenyl-induced porphyria after transplacental exposure was investigated using children born to mothers exposed to contaminated rice oil in central Taiwan in 1979. The exposure was to a mixture of thermally degraded polychlorinated biphenyls, polychlorinated quaterphenyls, & polychlorinated dibenzofurans, which had become mixed with the oil during processing. Women who became pregnant had children with high perinatal mortality and a dysmorphic syndrome. Seventy four controls and 12 siblings of the exposed children were included in the study. Four of the transplacentally exposed children, 2 controls and 1 sib had a type B hepatic porphyria; total porphyrin excretion was elevated in the exposed children as a group (95 ug/l, exposed; 81 ug/l, control); and 8 of the 75 exposed children and 2 controls had total urinary porphyrin concentrations of >200 ug/l. The children did not appear to have symptoms directly attributable to porphyria, but a mild disturbance in porphyrin metabolism appeared to be related to their intrauterine exposure.
People occupationally exposed to PCB's have relatively high PCB residue levels.
Digestive symptoms such as abdominal pain, anorexia, nausea, vomiting, jaundice, with rare cases of coma and death, may occur. At autopsy, acute yellow atrophy of the liver was found in lethal cases. ... Neurological symptoms such as headache, dizziness, depression, nervousness ... and other symptoms such as fatigue, loss of weight, loss of libido and muscle and joint pains were found in various percentages of exposed people. ... By the study of PCB-associated diseases in the general population, pathological pregnancies (toxemia of pregnancy, abortions, stillbirths, underweight births, etc) were frequently associated with increased PCB serum levels. ...
Mother's milk contaminated with PCB's appears to be a source of exposure for infants. Developmental abnormalities have been observed in PCB-intoxicated infants. Premature eruption of teeth was observed ... and larger frontal and occipital fontanelles, exophthalmos and the maintenance of an abnormally wide sagittal suture were observed. ...
Skin and mucous membrane changes; swelling of the eyelids, burning of the eye, and excessive eye discharge, burning sensation and edema of face and hands, simple erythematous eruptions with pruritus, acute eczematous contact dermatitis, chloracne, hyperpigmentation of skin and mucous membranes, discoloration of finger nails and thickening of the skin were reported.
Dental records were studied and dental exams given to children living in Taiwan transplacentally exposed to polychlorinated biphenyls (PCB) (Yu-Cheng babies) as confirmed by epidemiological studies in the early 1980s. Nine school aged Yu-Cheng males and 9 females were compared to an unexposed reference group of 26 males and 18 females on the prevalence of missing permanent teeth germ while taking congenital factors into account. Among 9 transplacental Yu-Cheng girls, 4 were missing permanent teeth germ due to congenital factors. Among the 18 girls in the reference group, none were missing permanent teeth germ due to congenital factors. Among 9 transplacental Yu-Cheng boys, 1 was missing permanent teeth germ due to congenital factors. Among the 26 boys in the reference group, 1 was missing permanent teeth germ due to congenital factors.
A job exposure matrix was developed linking the work tasks in the Swedish National Census of population 1960 to exposure to 50 single agents or groups of substances, including polychlorinated biphenyls. All 1,905,660 men (ages 20-64 yr) in 1960, reporting themselves as gainfully employed in the Census, were observed for the occurrence of urothelial cancer during the 1961-1979 period by linkage to the National Swedish Cancer Registry. Only subjects in 1 work task, electricians in electric power stations, were assigned exposure to polychlorinated biphenyls with a moderate predictive value. The relative risk (with 95% confidence interval) for this group was 1.3 (1.0-1.8) for urinary bladder cancer.
In Taiwan in 1979, rice oil contaminated with polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans was ingested by approx 2000 people. Blood samples were taken from 36 women who were potentially exposed, and 24 non-exposed women (controls). The frequency of sister chromatid exchanges in lymphocytes from their heparinized whole blood was assessed after culturing cells in the presence or absence of 40 uM alpha-naphthoflavone for 72 hr. There was no significant difference in baseline sister chromatid exchanges for PCB exposed compared to the control group (7.29 vs 7.61). In contrast, addition of alpha-naphthoflavone resulted in a dramatic induction of sister chromatid exchange frequencies in PCB exposed lymphocytes (p < 0.01). PCB exposed frequencies increased to 10.75, while those of the unexposed group only increased to 8.85.
Agent ... Polychlorinated biphenyls. Suspected human sites ... liver. /from table/
Mixtures of PCBs (e.g., Aroclors) have been commonly used to evaluate the immunotoxicity of PCBs and have been reported to suppress immune responses and decrease host resistance.
Adverse health effects in humans have occurred from exposure to all of them. /Dioxin, polychlorinated biphenyls, and dibenzofurans/
Children in the top 5 percent for PCB exposure showed delayed maturation of motor abilities.
There is one report of an increase in melanoma in PCB-exposed workers.
... Association between the maternal PCB level and the number and type of infections that occurred in the infants first 4 months of life.
Visual recognition memory was reduced at 7-month follow-up of the offspring of mothers exposed to PCBs in contaminated fish.
Yusho in 1968 ... and Yu-Cheng in 1979 ... affected more than 2000 people who ingested cooking rice oil contaminated with PCBs and related compounds. The disease was especially severe in children and with exposure in utero. The clinical syndrome included abnormal liver function tests, hepatomegaly ..., and electron microscopic alterations in the endoplasmic reticulum and mitochondria.
Selected adverse human health effects reportedly due to chemical toxicants. Chemical- polychlorinated biphenyls (PCBs) ... Organ- skin ... Effect- folliculitis and acneform dermatosis /from table/
Drugs considered to be proven human teratogens ... Polychlorinated biphenyls (PCBs) /from table/
Toxic effects of PCBs include chloracne, ocular irritation, arthritis, gastrointestinal symptoms, and hepatotoxicity.
Polychlorinated biphenyls (PCB; Arochlor, Inerteen, Kanechlor, Pyranol) have accidentally become widely distributed in food, especially in Japan where contaminated cooking oil consumed by 1000 people in 1968 caused a condition known as Yushu, and later in Taiwan where a similar epidemic occurred. The clinical characteristics were chloracne, brown pigmentation of skin, nails, and palpebral and bulbar conjunctiva, swelling and pigmentation of the eyelids, and eye discharge, particularly from hypersecretion from the Meibomian glands. Babies born to mothers with this type of poisoning likewise showed palpebral and conjunctival pigmentation, cheesy secretion in the conjunctival sac, and also exophthalmus.
An enlarged liver and increased absolute and relative liver weights are commonly reported as gross effects of PCB administration.
Acute and long-term exposures to PCBs have been reported to cause neurological and unspecific psychological or psychosomatic effects, such as headache, dizziness, nausea, depression, sleep and memory disturbances, nervousness, fatigue, and impotence.
Biopsy skin samples showed hyperkeratosis, dilation of the follicles, and an accumulation of melanin in the basal cells of the epidermis; melanin granules have also been observed in biopsy samples of the conjunctiva. Oedema of the arms and legs was also seen in some patients.
Skin exposure is important in the case of long-term exposure, even though the ambient concentrations may be low. ... Skin may be responsible for up to 20% of the total body uptake of PCBs is workers exposed ... .
Skin, Eye and Respiratory Irritations:
Irritating to skin and eyes.
Drug Warnings:
Food and Environmental Agents: Reported Sign or Symptom in Infant or Effect on Lactation: Polychlorinated biphenyls and polybrominated biphenyls: Lack of endurance, hypotonia, sullen, expressionless faces. /From Table 7/
Medical Surveillance:
Medical records should be kept for the entire length of employment of each worker and for the following 30 yr.
PRECAUTIONS FOR "CARCINOGENS": Whenever medical surveillance is indicated, in particular when exposure to a carcinogen has occurred, ad hoc decisions should be taken concerning ... /cytogenetic and/or other/ tests that might become useful or mandatory. /Chemical Carcinogens/
The assessment of PCB exposure can be accomplished through measurement of specific PCB's. However, due to the interference of whole blood components, serum or plasma is the preferred specimen for analysis. Blood Reference Ranges: Normal - less than 5 mg/l; Exposed - not established; Toxic - not established. Serum or Plasma Reference Ranges: Normal - less than 10 mg/l; Exposed - not established; Toxic - not established. Urine Reference Ranges: Normal - not established; Exposed - not established; Toxic - not established.
The assessment of PCB exposure can be accomplished through measurement of PCB's in adipose tissue, due to accumulation in this lipophilic tissue. This measurement may be useful for assessing the total body burden of PCB's. The normal background level of PCB's in adipose tissue is approx 1 to 2 ppm (1 to 2 mg/l).
There are three general categories of liver function tests: biochemical tests (serum enzyme activity, serum alkaline phosphatase, lactate dehydrogenase and bilirubin), tests of synthetic function (serum albumin, prothrombin time, alpha fetoprotein and serum ferritin), and clearance tests (bromsulphalein, indocyanine green, antipyrine test, aminopyrine breath test, caffeine breath test, D-Glucaric acid, 6-beta-hydroxycortisol and bile acids).
Evaluation of Peripheral Neuropathy: Nerve conduction study; Electromyography; Quantitative sensory testing; Thermography.
Evaluation of Central Nervous System Effects: Evaluation of CNS effects can be performed through neuropsychological assessment, which consists of a clinical interview and administration of standardized personality and neuropsychological tests. The areas that the neuropsychology test batteries focus on include the domains of memory and attention; visuoperceptual, visual scanning, visuospatial, and visual memory; and motor speed and reaction time. There is limited data on which components of the test batteries are best indicators of early CNS effects. Evaluation of Cranial Neuropathies: Evaluation of cranial nerve damage, as evidenced by symptoms such as loss of balance, visual function, smell, taste, or sensation on the face, can be accomplished through a phy | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
