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PCB fish impair memory, learning
Eating Lake Michigan catch poses health risk to adults, pregnancies

By Lee Bowman /
Scripps Howard News Service
October 17, 2001

    Eating large amounts of PCB-laden fish from Lake Michigan impairs the memory and learning of adults, a new study has found.
   Heavy fish eaters -- more than 24 pounds of sport-caught fish a year -- who are older than age 49 are having problems learning and remembering new verbal information, according to the researchers' report in the journal Environmental Health Perspectives.
   "This study suggests, for the first time, that PCB (polychlorinated biphenyls) body burdens in adulthood may be associated with impairments in certain aspects of memory and learning," said Susan Schantz, a researcher at the University of Illinois College of Veterinary Medicine who has been studying Lake Michigan fish-eaters since 1992.
   "The focus has been almost exclusively on increased health risks of exposure to children and pregnant women," Schantz said. "It had been assumed that mature adults are less susceptible than are developing fetuses, but this may not be the case."
   A decade ago, Drs. Joseph and Sandra Jacobsen of Wayne State University reported that exposure to low levels of PCBs disrupted fetal brain development, and caused neurological abnormalities and learning disabilities, including memory problems, in affected children.
   Until they were banned in the late 1970s, PCBs were widely used as electrical insulators and lubricants, and as extenders in paints and varnishes. The chemicals decompose very slowly and are still in use in a variety of older electrical equipment.
   In the Great Lakes, the PCBs make their way up the aquatic food chain and accumulate in increasing levels in the fatty tissue of game fish.
   The new study measured how fish-eaters with different concentrations of the chemical performed on tests of memory and verbal learning.
   They found that those with the highest blood PCB levels had difficulties recalling a story told just 30 minutes earlier. They were also less likely to be able to cluster according to meaning a group of words presented orally, suggesting problems in thinking ability.
   The researchers found that heavy fish eaters had higher levels of DDE (a breakdown product of the banned pesticide DDT), lead and mercury than did less frequent consumers, but the only negative cognitive effects were among people with high blood levels of PCBs.
   Schantz previously had reported that having high blood levels of PCBs had little or no significant effect on fine motor skills. And in the new research, they found no impact on other thinking factors, such as planning ahead, attention span and visual spatial function.

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