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Elevated PCB Levels
Blamed For Mental Decline

NEW YORK (Reuters Health) - For the first time, researchers have found that adults with high blood levels of polychlorinated biphenyls (PCBs) may have more memory and learning problems compared with people with lower blood levels of the chemicals.

Once used in everything from fluorescent lights and appliances to insulation and insecticides, PCBs were banned in 1977 as health hazards and carcinogens. But PCBs tend to linger in the environment, accumulating in the fatty tissue of birds, fish and mammals, and potentially having adverse health consequences in humans.

In a new study, investigators found that people who routinely ate PCB-contaminated sport-caught fish had more problems with learning and memory than people the same age with lower levels of PCBs in their body.

``The main finding was that older people--who ate sport-caught Great Lakes fish and had elevated body burdens of PCBs--did more poorly than non-fish eaters with lower PCB exposure on tests of verbal memory,'' said lead author Dr. Susan L. Schantz, of the University of Illinois at Urbana-Champaign.

``Specifically, they did not remember a short story that had been read aloud to them as well as the less-exposed people when they were asked to recall it 30 minutes later,'' she explained.

``Also, when asked to recall items from a shopping list that was read aloud to them, they tended not to group words by their meanings--a strategy that helps to boost recall,'' Schantz added.

In the study, Schantz and her colleagues evaluated the mental functioning of 101 adults aged 49 to 86 who ate more than 24 pounds of fish from Lake Michigan each year. This group was compared with 78 similarly aged adults who ate 6 pounds or less of fish from Lake Michigan every year.

On average, the men had blood PCB levels of 15.2 parts per billion (ppb) and women had 9.2 ppb. Non-fish eaters had much lower levels of the chemical in their blood, according to the report published in the June issue of Environmental Health Perspectives.

``Previously, researchers felt it was primarily children exposed to PCBs in utero who were at risk for neurological problems. This study suggests that mature adults who have elevated exposure may also be at risk,'' Schantz told Reuters Health.

Although the researchers do not fully understand the mechanisms through which PCBs impair brain function, there are some new studies showing that PCBs disrupt calcium signaling in nerve cells and this may turn out to be related to the learning and memory problems that have been seen in laboratory animals, children and now adults exposed to PCBs, she explained.

PCB levels vary from person to person, and largely depend on an individual's diet, life style and where they live. The average PCB blood level for young adults living in the United States is around 2 ppb. Older people tend to have higher levels of PCBs in their blood as do people who eat fish from contaminated waters such as the Great Lakes or the Baltic Sea for example, Schantz noted.

What's more, Shantz pointed out that the only treatment is prevention.

``Once PCBs are in the body they get stored in body fat and remain for a very long time. That's why older people tend to have higher levels of PCBs--they gradually build up (bio-accumulate) over the life span,'' she said.

``There are no known drugs or procedures to increase excretion (of PCBs). That is why it is so important for people to be aware of the fishing advisories in the Great Lakes and avoid eating fish that are contaminated,'' Schantz concluded.

SOURCE: Environmental Health Perspectives 2001;109:605-611.


Reference Source 89

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