8-4 Polychlorinated biphenyls (PCBs) are compounds that were once used as an insulating material in electrical transformers before being banned in the United States during the 1970s because of concerns about their toxicity.

Despite the ban, PCBs can still be detected in most people because they are persistent in the environment and tend to accumulate in fat tissue as animals that absorb PCBs eat other animals that have absorbed PCBs. One of the major current sources of human PCB exposure is eating fatty fish caught from contaminated waters. In the early 1980s, the husband and wife team of Joseph Jacobsen and Sandra Jacobsen†

began a prospective study to examine the relationship between PCB levels in a group of women who ate Lake Michigan fish and the intellectual development of their children. The amount of PCBs (ng/g of fat) detected?