Children exposed in utero to low levels of polychlorinated biphenyls [PCBs] have suffered long-term brain damage, decreased learning skills, and low I.Q. scores according to a study of 212 eleven year olds whose mothers had elevated concentrations of PCBs as a result of eating Lake Michigan fish contaminated with the chemical. These mothers at birth had PCBs in the blood and breast milk that was slightly higher than in the general population as a result of having consumed approximately 12 pounds of Lake Michigan fish in the preceding six years.
This study raises serious issues for the children of women employed in the electrical industry who were exposed to PCBs in the manufacture of motors, transformers, switches and related electrical equipment. Oil with PCBs for many years was as a coolant and to dampen sparks because the product was long-lasting, had a high tolerance for heat and did not readily breakdown. It has been banned in the U.S. since the mid-1970s, but industrial residues still persist in the environment and are a source of food contamination as they are taken up by plants that are eaten by fish. Once consumed by humans the PCBs are deposited and stored in fat, virtually permanently. Numerous studies have documented increased levels of PCBs in Great Lakes fish.
Risks associated with developmental delays have been well documented in the scientific literature.
In a previous study in North Carolina, Rogan, W. J. et al Polychlorinated Biphenyls [PCBs] and Dichlorodiphenyl Dichloroethene [DDE] in Human Milk: Effects of Maternal Factors and Previous Lactation, American Journal of Public Health 1986, 76:172-7, scientists showed that fetal exposure to PCBs affected neural development in children.
An earlier study by Drs. Jacobson showed the cohort of 313 children had suffered adversely impacted postnatal growth and short-term memory deficits in infancy and at age 4. Jacobson, J.L. and Jacobson S. W. et al Effects in Utero Exposure to Polychlorinated Biphenyls and Related Contaminants on Cognitive Functioning in Young Children, Journal of Pediatrics 1990, 116;38-45.
Similar results have been found in Chinese children exposed to mothers who had eaten rice oil that contained PCBs.
The present Wayne State study followed up the 313 children previously tested by Drs. Jacobson and re-tested 212 at age eleven. Of this group 167 were born to mothers who had consumed fish from Lake Michigan contaminated with PCBs. The children were administered the Wechsler Intelligence Scales for Children I.Q. instrument, the Wide Range Achievement Test – Revised and portions of the Woodcock Reading Mastery Tests -Revised.
“Prenatal exposure to polychlorinated biphenyls was associated with significantly lower full-scale and verbal I.Q. scores. An analysis of covariance indicated that the effect was primarily in the most highly exposed children . . . . . prenatal exposure to polychlorinated biphenyls was associated wit poorer verbal comprehension and freedom from distractibility.” At 786.
These findings corroborate earlier findings by Drs. Jacobson, as well as other researchers, and show that children whose mothers were exposed to PCBs during pregnancy will have decreased “intellectual ability, short-term and long-term memory and focused and sustained attention,” all of which are critically necessary for success in school. Although no children were found to have been mentally retarded, the loss of I.Q. in this group is sufficient to impact learning to read and general school performance.
Most significantly, children who had suffered the highest level of maternal exposure were three times as likely to have I.Q. scores that tested in the low normal range and twice as likely to have difficulty in learning to read.
Drs. Sandra and Joseph Jacobson have concluded that children exposed in utero to PCBs have the same disabilities as children exposed to low levels of lead. The full study is reported in the New England Journal of Medicine: Intellectual Impairment in Children Exposed to Polychlorinated Biphenyls In Utero, New England Journal of Medicine, September 12, 1996, 335:783.
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