Men and woman who accumulated large amounts of polychlorinated biphenyls (PCBs), primarily through eating Great Lakes fish, exhibit subtle memory problems, according to a new study.
PCBs are oily fluids that have been used principally as insulation in electrical transformers. Because these toxic dioxinlike compounds break down slowly, they persist in the environment for decades and are now slated for a global phaseout (SN: 6/2/01, p. 343: Nations sign on to persistent-pollutants ban).
Studies have shown that children exposed to fairly small amounts of PCBs in the womb can develop learning problems and IQ deficits that persist at least into their preteen years (SN: 9/14/96, p. 165). However, far larger exposures after birth–from breast milk–had no discernable effect, notes Joseph L. Jacobson of Wayne State University in Detroit, a coauthor of those studies.
"So, if a baby isn't vulnerable after birth, we wouldn't have expected t