Evidence of an age-related threshold effect of polychlorinated biphenyls (PCBs) on neuropsychological functioning in a Native American population
Author:
Richard F. Haase, Robert J. McCaffrey, Azara L. Santiago-Rivera, Gayle S. Morse, and Alice Tarbell
Date Published:
2008
Description:
Polychlorinated biphenyls (PCBs) have been suspected for some time of having adverse effects on
neuropsychological functioning in humans. While there is evidence of slowing of cognitive function in
children associated with exposure to PCBs, the evidence of comparable effects on adults is far less well
understood. We report here on the neuropsychological evaluation of 277 Native American adults,
ranging in age from 18 to 79, who were exposed to PCBs by way of environmental contamination in the
St. Lawrence region of upstate New York. PCB body burden was estimated by 101 PCB congeners and
neuropsychological functioning was assessed by a battery of 18 tests. Spline regression models were
fitted to the latent variables of memory, motor function, and higher-order executive functioning. After
adjusting for age, gender, and education the analyses revealed a threshold effect of PCBs at
approximately 2 ppb. An age-by-PCB interaction effect was also observed for several variables which
suggests that the threshold effect was largely confined to the age range of 40–79 and was not observable
in the 18–40-year-old group. Implications of these results are discussed in comparison to previously
published similar work with adults and in terms of its potential clinical meaningfulness.
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