This became clear after Grandjean and colleagues investigated the response to vaccination in two companions from the Faroe Islands, known for its high level of PCB. This was measured by examining the blood sample from the mother while she was expecting.
Among the 119 children who got the diphtheria and tetanus vaccines and examined at 18 months, revealed the greater the PCB exposure level, the antibody body protection lowered to the extent of exposure. The researchers also observed that nearly 21 percent of the seven year olds had antibody levels that were insufficient to accord complete protection. Additional research is required to establish this finding.