Chapter 6: PCBs
PCBs, an abbreviation for polychlorinated biphenyls, represent a family of 209 colorless and odorless chemicals that were widely used in electrical equipment such as transformers, and capacitors. It is estimated that more than 3.4 billion pounds of PCBs were produced between 1929, when they were first introduced, and 1977, when production was prohibited in the United States, because of evidence they build up in the environment and cause harmful health effects. Although PCBs have not been used for decades in the U.S. (they were banned in the European Union in 1985 and in Russia in 1993), they still enter our bodies and the bodies of our children. The characteristics that made PCBs attractive for industrial application—stable molecular structures and flame resistance—make them difficult to get rid of. PCBs persist and circulate in the environment for decades after their release. PCBs accumulate in adipose tissue and organs in animals and people and biomagnify as they move up the food chain.
Of the billions of pounds of PCBs produced in the U.S. before 1977, about 30% entered the environment through direct discharges into the air, land, and water. The remaining half results primarily from improper disposal of products containing PCBs, which continues to this day. There are numerous electrical transformers and other closed system devices still in use which contain PCBs. Products made before 1977 that may contain PCBs include fluorescent lighting fixtures and electrical devices containing PCB capacitors, and old microscope and hydraulic oils. Most PCBs enter the environment and accumulate in rivers, lakes, and ultimately the ocean.
PCBs biomagnify by entering the food chain in small organisms and increasing in concentration as larger fish and mammals eat the smaller organisms. Large, fatty fish like lake trout, carp, and bass have been found to contain very high concentrations of PCBs. Some fish contain such high levels that they are considered unsafe for human consumption. In Oregon, there are five fish and/or shellfish advisories due to PCBs, including the Bonneville Dam, Lower Columbia, Columbia Slough, Portland Harbor, and Willamette.99 The Oregon Department of Human Services advises that fish and shellfish in these waterways be either avoided or prepared in a way that minimize PCB exposure, such as grilling or other cooking methods that remove fat before consumption.
PCBs can be absorbed through the skin, lungs or your digestive tract. For most of us, food is the most significant source of exposure. Foods most likely to contain PCBs include milk, eggs, chicken, turkey, beef, and fish. PCBs are stored and accumulate in the body's fatty tissue. While PCB levels in most of our food have declined since 1977, three decades later we continue to ingest PCBs when we eat fish, meat, and dairy products.100 Exposure to PCBs can also occur through occupational accidents and handling contaminated soil.
PCBs in Oregonians
We tested for the level of total PCBs in the blood serum of our participants. PCBs were detected in the blood of all ten participants (Figure 8). The total PCB concentration ranged from 0.4 – 5.5 mg/L (or ppb), with a median concentration of 0.8 ppb which is similar to the total median PCB concentration detected in the Washington Pollution in People report (0.95 ppb)101 and somewhat below the national median range of 0.9 – 1.5 ppb.102
The highest PCB concentration, at 5.5 ppb, was detected in Danya Rumore. This level is more than three times the national median of PCB exposure. Danya did not report consuming high levels of PCB-containing fish, suggesting that her PCB exposure is from either other dietary sources such as fatty meat and dairy products or from contact with electrical equipment or with certain building insulation and caulking materials.
Figure 8. Total PCBs were measured in participant blood serum.
Health Effects of PCBs
The most commonly observed health effects in people exposed to large amounts of PCBs are skin conditions such as acne and rashes. Studies in exposed workers have shown changes in blood and urine that may indicate liver damage.103
Research studies in both animals and exposed workers have demonstrated that PCB exposure can increase the risk of a variety of cancers such as malignant melanoma, non-Hodgkin's lymphoma, and brain, liver, biliary tract, intestinal, and lung cancers.104 The National Toxicology Program considers several PCB mixtures to be "reasonably anticipated" human carcinogens,105 and the EPA considers PCBs to be probable human carcinogens.106 Additional negative health impacts associated with PCB exposure include respiratory effects, gastrointestinal damage (nausea, vomiting, abdominal pain), eye irritation, increased susceptibility to infection, and hypothyroidism.107
Women who consume PCBs in their diet readily pass them to their children in breast milk; infants may get 6 to 12% of their lifetime exposure to PCBs from breastfeeding alone.108 PCB exposure in the womb or during lactation is associated with decreased IQ and impaired psychomotor development and decreased immune function.109 However, the benefits from breast feeding outweigh any risks from exposure to PCBs in a mother’s milk (see Sidebar: “Breast Feeding Is Best”).
Research involving animals and humans suggest that exposure to PCBs in utero is of particular concern.110 Studies of children in the U.S., Germany, and the Netherlands have shown that those children with greater prenatal exposures (measured by levels in umbilical cord blood or the mother’s blood) performed worse on tests of brain development than children with lower exposures, linking prenatal PCB exposure to brain development deficits.111 Research on children in the Faroe Islands shows an association between increased prenatal and postnatal PCB exposure and decreased antibody production in vaccinated children.112
In animal studies, PCBs cause a wide variety of effects including liver and thyroid tumors; kidney, gastrointestinal, immune, urinary tract, and reproductive toxicity; altered lipid and carbohydrate metabolism; reduced fertility; and birth defects.113 Specific birth defects include reproductive tract and skeletal abnormalities. PCBs have been shown to be endocrine disruptors in animals because they alter thyroid and adrenal hormone levels and function. PCBs have been associated with significant neurotoxicity, including decreased exploratory behavior, learning, spatial and non-spatial discrimination, auditory deficits and altered levels of brain neurotransmitters (dopamine and serotonin).114
Policy Changes Needed
The continuing story of PCBs is both hopeful and disheartening. Based on scientific evidence linking PCB exposure to negative health outcomes, this chemical was banned in the U.S. 30 years ago—demonstrating that action can be taken given the right set of circumstances. Unfortunately, although the levels of PCBs have declined in most human populations, we still face levels that could be causing harm—long after regulatory action was taken.
The most recent EPA Toxic Release Inventory (TRI) for Oregon shows that PCBs are only released from hazardous waste landfills and other contained sites. There are no reported point source releases of PCBs to the air or water. Based on this, PCB contamination cannot be reduced through the use of OREGON DEQ air or water discharge permits. OREGON DEQ and EPA are addressing PCB releases from known contamination sites such as the Portland Harbor Superfund site through their cleanup program.
In addition to these cleanup efforts, there are further actions that can be taken to reduce our exposure to this toxic threat.
- Establish and implement erosion control programs to minimize the release of PCBs into waterways. Since PCBs are ubiquitous in the soil, erosion control practices—in both urban and rural areas—can help to minimize releases of PCBs into our waterways.
- Establish programs to collect and safely dispose of remaining PCB-containing products. Oregon needs to establish a program to identify and properly dispose of old PCB fixtures before they end up in landfills and incinerators.
Reducing Your Exposure to PCBs
The greatest source of exposure to PCBs for most Oregonians is food. While you cannot completely eliminate PCBs from your diet, you can minimize your exposure, specifically:
Choose fish wisely. In Oregon, there are five fish advisories due to PCBs (Bonneville Dam, Lower Columbia, Columbia Slough, Portland Harbor, and Willamette).115 Check with state advisories prior to eating sport-caught fish or shellfish, which are known sources of PCB exposure. Commercial fish that are high in PCBs include Atlantic or farmed salmon, bluefish, wild striped bass, white and Atlantic croker, blackback or winter flounder, summer flounder, and blue crab. Resident species in Oregon containing high in PCBs include northern pikeminnow, largescale sucker, smallmouth bass, and mountain whitefish.
Prepare fish to minimize PCB exposure. When preparing fish, remove the skin, trim the fat, and broil, bake, or grill the fish so that the fat drips away.
Make your meat lean and limit your consumption of dairy fat. When it comes to meat, choose lean meat cuts and cut off visible fat before cooking meat. Avoid frying meat in lard, bacon grease, or butter. For dairy products, opt for low-fat options.
Breast Feeding Is Best.
Despite concerns over the presence of environmental contaminants in breast milk, breastfeeding is still by far the best option for the baby’s health and mother-baby bonding, when possible. Infants who do not breastfeed or do so for only a short time have more acute illness such as ear, lung, and urinary infections. Exposure to foods other than human milk in the first few months of life can increase the risk of life-long autoimmune illnesses. Without breastfeeding, infants do not receive optimal nutrition, important hormones, protective immune factors, and promoters of brain development.
Formula feeding does not eliminate children’s exposure to toxic chemicals and may increase exposure due to contaminants and leaching of chemicals from plastic baby bottles. According to the World Health Organization, “the accumulated data overwhelmingly support the positive health value of breastfeeding infants.” For more information, see Why Breast-Feeding is Still Best for Baby, by Physicians for Social Responsibility here.
