Fish consumption and breast milk PCB concentrations among Mohawk women at Akwesasne

A study was conducted to determine the relation between the consumption of contaminated local fish and concentrations of total polychlorinated biphenyls (PCBs) and 68 PCB congeners in the milk of nursing Mohawk women residing near three hazardous waste sites. From 1986 to 1992, 97 Mohawk women were interviewed and donated at least 50 ml of breast milk. The comparison population consisted of 154 Caucasians. After adjustment for potential confounders, Mohawk mothers who gave birth in 1986-1989 had a geometric mean milk total PCB concentration of 0.602 ppm (fat basis) compared with 0.375 ppm for the control group (p = 0.009). These Mohawk women also had significantly higher geometric mean concentrations of nine congeners. Beginning in 1990, however, there were no significant differences between the Mohawk women and the comparison group. Estimated cumulative lifetime exposure from local fish consumption was significantly related to milk total PCB and to three congeners only among those Mohawks who gave birth from 1986 to 1989. The reduction in breast milk PCB concentrations parallels a corresponding decrease in local fish consumption and may be the result of the advisories that have been issued over the past decade recommending against the consumption of local fish by pregnant and nursing Mohawk women.