The findings, published in the February issue of the journal Toxicological Sciences, come from a study focusing on the effects of combined exposure of the two commonly found environmental contaminants on motor function driven by the cerebellum.
"Because people are exposed to these toxicants by eating fish taken from ecosystems where these chemicals accumulate, our findings suggest that we should seriously consider the possible impact of their additive toxic effects on human health," said Susan L. Schantz, a professor of veterinary biosciences at the University of Illinois at Urbana-Champaign.
Previous laboratory studies had suggested that the two chemicals act together to impair nervous system function. A study in February's issue of the Journal of Pediatrics found that exposure to methylmercury causes heart damage and impairs brain growth.
The new study -- pursued as part of the doctoral dissertation by Schantz's graduate student Cindy S. Roegge -- shows that motor skills were not significantly affected by methylmercury exposure alone, but when paired with PCBs the combined effect during development dramatically impacted the pups' skills in one of three motor tests.
The research was done for the federally funded FRIENDS Children's Environmental Health Center, a five-institution consortium based at the College of Veterinary Medicine at Illinois. Schantz is director of FRIENDS (Fox River Environment and Diet Study), which is studying the effects of exposure to toxicants in fish being eaten in large quantities by Laotian and Hmong refugees in Green Bay and Appleton, Wis.