Evidence for neuropsychological effects of PCBs in environmental studies: Getting better all the time

This invited response to the paper by D.V. Cicchetti, A.S. Kaufman, and S.S. Sparrow (CKS), and the responses by the investigative teams of the studies criticized by them, addresses specific errors of logic and interpretation by CKS, and integrates comments made by the study investigators. CKS provide a flawed analysis of the literature on the neuropsychological effects of PCBs identified in epidemiological studies. Arguments regarding the inadequacy of study design and data analysis are for the most part factually in error, unimportant, superceded by later testing or analysis within a study, or if true, would bias results toward the null rather than finding spurious effects. They also fail to differentiate between small effects in an individual and the societal consequences of such effects, and fail to recognize the overall consistency of effects among studies. In fact, the literature is remarkably consistent in documenting adverse consequences of developmental exposure to PCBs in humans. In addition, contrary to assertions by CKS, developmental studies in monkeys documented cognitive effects at body burdens observed in human studies. (C) 2004 Wiley Periodicals, Inc.