PCBs in Sport Fish:
Answers to Questions on Health Effects

Polychlorinated biphenyls (PCBs) are a large group of industrial chemicals with a common structure. They are oily liquids or solids, clear to light brown in color, and have no smell or taste. PCBs do not occur naturally in the environment. Along with methylmercury, they pose the greatest health concern in eating sport-caught fish in several parts of the state, including San Francisco and Santa Monica bays. They are also one of the main chemical contaminants that have been found in fish in other parts of the country.

Excessive exposure to PCBs may cause a wide variety of adverse health effects. Our knowledge of the effects is based on both studies of people exposed in the workplace or who ate contaminated food, and on experimental studies with animals. Of particular concern are the effects on development in infants whose mothers have been exposed before and during pregnancy.

This document will give you information about PCBs and their potential health effects. It will explain the purpose of the health advisories that the Office of Environmental Health Hazard Assessment (OEHHA) has issued in areas where high levels of these chemicals have been found in fish. These health advisories give guidelines for limiting the amount of sport fish you eat and tell how to prepare and cook fish in a way that will remove some of the PCBs.

Summary of main points

• PCBs had many industrial uses before their manufacture ended in 1977.

• PCBs remain in the environment for years and can build up in fish.

• Eating contaminated fish can cause PCBs to build up in your body over time. PCBs become stored in your fat.

• In certain areas in California, PCBs have been measured in sport-caught fish at levels well above 100 ppb. These elevated levels may pose a health concern. OEHHA advises you to limit how much you eat of fish taken in these locations.

• Some of the children whose mothers ate fish from the Great Lakes containing high levels of PCBs had delayed development of mental functions and muscular coordination. The levels of PCBs in the fish eaten by these mothers were 5 to 10 times higher than those found in fish in San Francisco Bay or other California waters where PCBs have been found at elevated levels.

• PCBs can be transferred to nursing infants through breast milk. However, breast feeding is very beneficial to your baby. Do not stop breast feeding without first speaking to your doctor.

• PCBs may cause cancer in humans because they have been found to cause cancer in laboratory animal studies.

• Workers have experienced skin and eye irritation from contact with PCBs in the workplace. Many serious health effects have also been seen in studies with animals. These effects include liver, stomach and thyroid gland injuries; anemia; chloracne; and effects on reproduction.

• At the PCB levels found in fish in California, a single large meal, or a few such meals, of fish should not make you ill. Frequent eating of PCB-contaminated fish over a period of years may lead to the build up of PCBs in your body. Although this might not lead to a distinct illness, prevention is the best remedy. The fish consumption guidelines that we provide in the advisories will protect health by preventing PCBs from building up to unsafe levels in your body.

• You can lower the amount of PCBs in fish by following preparation and cooking methods that get rid of fat.

How were PCBs used and how did they get into fish?
The PCB group consists of 209 individual compounds, called congeners because they are structurally related. Commercial mixtures containing 40 to 70 PCB congeners were marketed under the trade name Aroclor, such as Aroclor 1260. Because they do not burn easily and are good insulators, PCBs were used extensively in transformers, capacitors, and other electrical equipment.

PCBs have entered the environment partly because of accidental leaks and fires in electrical equipment, past disposal in dumps, accidents in transport, and leakage from hazardous waste sites. Their widespread distribution in the environment was also caused by their use as plasticizers, in inks and dyes, as ingredients in pesticides, in adhesives, in protective wood coatings, and in carbonless-copy paper.

Manufacture of PCBs stopped in the United States in 1977 because of evidence that PCBs build up in the environment and cause harmful effects. In the environment they persist for a long time. Usually they stick to soil or sediments and may remain there for years, but they also are found in the air, water and food. PCBs enter the bodies of fish from water, sediment, and from eating prey that have PCBs in their bodies. PCBs build up in fish and can reach levels hundreds of thousands of times higher than the levels in water.

How might I be exposed to PCBs?
Eating contaminated fish is a major way of being exposed. Exposure to PCBs can also come from breathing workplace air (indoor air around older electrical parts or outdoor air at waste sites) or from skin contact with contaminated soil.

What levels of PCBs have been found in fish in California?
In 1994, the San Francisco Water Quality Control Board conducted a pilot study on chemical contaminants in fish in San Francisco Bay and found significant levels of PCBs in fish throughout the bay. The levels of PCBs ranged from a low of 21 parts per billion (ppb) in brown smoothhound sharks to a high of 638 ppb in white croaker. The highest levels of PCBs were found in fish taken at sites near industrial parts of San Francisco and Oakland, but elevated levels were also found in the north and south parts of the bay.

These levels are about the same, or less than, levels of PCBs found in fish from Santa Monica Bay. In both of these bays, white croaker, a very fatty fish, had the highest amounts of PCBs. These levels are greater than PCB levels in fish from San Diego and Monterey Bays. They are also higher than PCB levels found in most lakes and rivers in California except for some freshwater sites that are mainly in Los Angeles and Orange counties.

Levels of PCBs in San Francisco and Santa Monica bays are about five to ten times below the levels found in sport fish in the Great Lakes region. That region has some of the most extensive PCB contamination in the country.

OEHHA has issued advisories where sport-caught fish have been found to contain PCBs above 100 ppb. The advisories provide guidance on how much fish you can safely eat. The consumption limits are often specific to the species and fishing locations. The advisories are available from OEHHA and are printed in the California Sport Fishing Regulations booklet.

Are the levels of PCBs going down?
Data from the California State Mussel Watch program indicate that the levels of PCBs, DDT, and chlordane in San Francisco Bay have been steadily declining in the past 15 years since measurements have been taken. The PCB levels in the bay are four to seven times lower than when they were first measured. Although they are going down, PCBs last for a long time and are still at levels of concern in some areas.

What happens to the PCBs when you eat contaminated fish?
If you swallow food, water, or soil contaminated with PCBs, most of the PCBs will pass from the stomach into the bloodstream within minutes, and be distributed throughout your body. Most of the PCBs become stored in fatty tissue. Human milk may contain more PCBs than blood due to the high fat content of milk. Newborns can be exposed to PCBs through their mothers’ milk, and fetuses may be exposed to PCBs from their mothers’ blood through the placenta.

The most highly chlorinated PCB congeners are the most fat soluble and stay in the body the longest. Other congeners are eliminated more rapidly from the body. The PCB mixtures found in fish and in human tissues may differ significantly from the commercial PCB mixtures, but commercial mixtures are what have been used in studies with laboratory animals to determine toxicity. Therefore, some scientists prefer to evaluate health effects based on human studies. These studies usually compare populations who have been exposed to PCBs, such as in the workplace or from eating highly contaminated fish, with populations that have not been exposed. Human studies, however, also have limitations, as noted in examples below.

Next page

You will need the free program Adobe Acrobat Reader to view or print PDF files

For help with this web site please contact the Web Mistress