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What do the results mean?

Health risk depends on many things, including how much fish is eaten, the amount of contamination in the fish, how long someone has been eating contaminated fish and whether there is exposure to contaminants from other sources.

The results show that all of the tested bullhead catfish were contaminated with PCBs and DDE. Most of the fish were also contaminated with DDT. A few fish were also contaminated with other pesticides. The level of PCBs measured in the fish from the Souhegan River may pose a health risk to the people who eat them.

The risks of cancer from eating contaminated fish can not be predicted with certainty; but based on the fish sampling results and the potential for these health effects the public should be advised to limit consumption of fish caught from this area of the Souhegan river.

What are PCBs?

PCBs are a mixture of very similar chemicals4. They were used in electrical equipment such as transformers and capacitors. Manufacture of PCBs stopped in the U.S. in 1977 because of environmental and health concerns. PCBs were used commercially, not as individual chemicals, but as mixtures of several PCBs

Health Effects of PCBs

The widespread occurrence and environmental persistence of PCBs have caused concern over their possible health effects4. Animal studies in which PCBs were fed to animals throughout their lifetime have found that these animals develop liver cancer. Based on these results the EPA has classified PCBs as chemicals that probably can cause cancer in humans.

Other animal studies have found that feeding small amounts of PCBs to animals for several weeks or months caused injuries to the skin and nails, liver, stomach, thyroid, and immune system4. Animals also had anemia, acne, and damaged ability to reproduce. Some of the same effects were also found in the offspring of animals that were fed PCBs. The immune system and skin and nails appear to be the most sensitive to PCBs. It is not known if PCBs can harm the immune system in humans, however, these effects are seen in several different animal species.

Recent studies of children whose mothers ate PCB-contaminated fish suggest that PCBs may have neurobehavioral effects in children4. These findings are not certain because other chemicals in the fish may have caused the effects that were observed.

What are the other chemicals that were found in the fish?

The other chemicals found in the fish are pesticides or their breakdown products. For example, 4,4'-DDD and 4,4'-DDE are breakdown products of the pesticide 4,4'-DDT7. Many of these chemicals are no longer used or have been banned in the U.S.

Even though these pesticides are no longer used, they are still present throughout the environment. They break down slowly and are found in many rivers and lakes. These chemicals can build up over time in the bodies of fish and other animals, and if the levels get high enough, can affect their health. People who eat contaminated fish over months or years can build up amounts of these long-lasting chemicals in their bodies, which can affect their health or if pregnant, the health of their fetuses. The levels of these chemicals measured in the fish are too low to directly cause health problems.

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