An association between in utero polychlorinated biphenyl (PCB) exposure and impaired childhood intellectual functioning has been reported, but the potential impact of PCB exposure during adulthood on intellectual functioning has received little attention. We assessed the impact of PCBs and other fish-borne contaminants on intellectual functioning in older adults. The subjects were 49- to 86-year-old Michigan residents recruited from an existing cohort. Fish eaters ate > 24 lb of sport-caught Lake Michigan fish per year and non-fish eaters ate < 6 lb of Lake Michigan fish per year. A battery of cognitive tests including tests of memory and learning, executive function, and visual-spatial function was administered to 180 subjects (101 fish eaters and 79 non-fish eaters). Blood samples were analyzed for PCBs and 10 other contaminants. We evaluated cognitive outcomes using multiple regression. PCBs and dichlorodiphenyl dichloroethene (DDE) were markedly elevated in fish eaters. After controlling for potential confounders PCB, but not DDE, exposure was associated with lower scores on several measures of memory and learning. These included the Weschler Memory Scale verbal delayed recall (p = 0.001), the semantic cluster ratio (p = 0.006), and list A, trial 1 (p = 0.037), from the California Verbal Learning Test. In contrast, executive and visual-spatial function were not impaired by exposure to either PCBs or DDE. In conclusion, PCB exposure during adulthood was associated with impairments in memory and learning, whereas executive and visual-spatial function were unaffected. These results are consistent with previous research showing an association between in utero PCB exposure and impairments of memory during infancy and childhood.
Serum samples from 285 4-year-old Michigan children were evaluated for levels of 11 environmental contaminants. Polychlorinated biphenyls (PCBs) were found in half the samples tested; polybrominated biphenyls (PBBs) in 13-21 percent; dicholorodiphenyl trichloroethane (DDT), in more than 70 percent. Nursing (Mothers' milk) was the principal source of these exposures. Congener-
Several recent reports indicate that occupational exposure to electric and magnetic fields may be associated with increased risk of neurodegenerative diseases. To address that hypothesis, we analyzed data from a cohort study of electric utility workers. We examined exposure to magnetic fields, assessed as duration of work in exposed jobs and through an index of cumulative exposure based on magnetic field measurements, in relation to mortality from Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, considering both underlying and all mentioned causes of death. Adjusted mortality rate ratios based on Poisson regression models indicate no association between magnetic fields and Parkinson's disease and little support for an association with Alzheimer's disease mortality. Mortality from amyotrophic lateral sclerosis was positively associated with duration of work in exposed jobs [rate ratio = 2.0, 95% confidence interval (CI)= 0.7-6.0; and rate ratio = 3.1, 95% CI = 1.0-9.8, based on underlying cause for 5 - < 20 years and > or = 20 years vs < 5 years, respectively], as well as with cumulative magnetic field exposure with a > or = 20-year lag (rate ratio = 2.3, 95% CI = 0.8-6.6; and rate ratio = 3.0, 95% CI = 1.0-9.2, for exposure in the middle and upper intervals relative to the lowest interval, respectively).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.