Lake Ontario fish linked with high levels of PCBs in breast milk

Women who eat fish from Lake Ontario have significantly higher levels of PCBs and pesticides in their breast milk than women who do not eat Lake Ontario fish, according to a University at Buffalo study.

Findings in the study also showed that concentrations of these toxins in breast milk declined as the number of children and the time spent breast-feeding increased. This implies that breast-feeding is a significant way of eliminating PCBs in women.

“This work supports previous studies that also indicate that lactation is a primary means of removal of these persistent contaminants in the female,” said Paul J. Kostyniak, the primary author on the study.

“Most of a woman’s excretion occurs via the milk during breast-feeding, so generally, the more children and the more breast-feeding, the lower the levels will be.

“The data on individual PCB subtypes also allow researchers to quantify exposures to specific subtypes, all of which have different rates of elimination from the body, different degrees of toxicity and, in many cases, different toxicological effects.”

The study was conducted among members of the New York State Angler Cohort. This group is composed of licensed anglers and their spouses or partners from 16 counties surrounding Lake Ontario: a total of 10,517 men and 7,477 women who were between the ages of 18 and 40 when the study began.

The study was undertaken in 1991 to determine the health consequences of eating fish from Lake Ontario, known to be the most polluted of the Great Lakes.

Many contaminants found in Great Lakes fish have been linked to adverse reproductive and developmental effects in wildlife populations that eat the fish. Dietary intake is the main source of exposure to these compounds for the general population and is a critical determinant of the toxicants in human milk.

This research reports results of the analysis of 100 breast-milk samples from 98 lactating women in the cohort. Fifty of the women were nursing a first-born, while the remaining 48 had two or more children. The women completed a questionnaire that provided data on the date of the milk sample; number of children; history of breast-feeding; height and weight before, during and after the most recent pregnancy, and detailed information on amount and types of fish eaten from Lake Ontario and its tributaries in the 12 months before the most recent pregnancy.

Milk samples were analysed for 77 PCBs; DDE, a metabolite of the pesticide DDT, and the pesticides hexachlorobenzene (HCB) and Mirex. Analysis of milk samples showed that DDE and nine PCBs were found in all 100 samples.

Milk samples from fish-eaters had significantly higher levels of several PCBs than that of non-Ontario fish-eaters. The two most prevalent PCB subtypes, shown to be 30 percent higher, were also the most prevalent contaminants in Lake Ontario fish. DDE level was not related to fish consumption from Lake Ontario, analysis showed.

Kostyniak said this type of data is critical for estimating the doses of individual PCBs to assess exposure risk in newborns. A prospective study of pregnancy rates and of children born to mothers in the New York State Angler Cohort is being conducted by UB researchers in the Department of Social and Preventive Medicine.

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