Diet danger: contaminated fish

Eating contaminated sport fish from Lake Ontario is associated with shortened menstrual cycles, epidemiologists from UB have found. They also reported that the fish consumption was associated with a small, but statistically insignificant, delay in the time it took women to become pregnant.

The results are from two separate studies that are among the first to assess the dietary effect of low-level environmental exposure to organochlorines, heavy metals and pesticides, all recognized reproductive toxicants, on the reproductive process in humans.

Women enrolled in New York State Angler Cohort provided data for the studies. The cohort, composed of 10,518 male anglers, 918 female anglers and 6,651 spouses or partners of male anglers, was formed in 1991 to provide a representative sample of fishing-license holders between 18 and 40 from the 16 counties near Lake Ontario.

Eating Great Lakes sport fish delivers a mixture of toxic chemicals, including PCBs at a level estimated to be 4,300 times greater than through exposure in the air or via drinking water. Many of these chemicals accumulate in the body. Lake Ontario fish are reported to have more than twice the amount of dioxin, mirex and PCBs than fish from the other Great Lakes, a finding that has resulted in the New York State Department of Health recommending that women of childbearing age eat no Lake Ontario fish.

For the two studies, researchers from UB's Department of Social and Preventive Medicine assessed both time-to-pregnancy, a measure that can reveal conception delays, and length and regularity of menstrual cycle, aspects that affect a woman's fecundity. The time-to-pregnancy study, headed by Germaine Buck, associate professor of social and preventive medicine, involved 874 women who were trying to become pregnant between 1991 and 1993. Information on duration and frequency of sport-fish consumption was collected when participants enrolled in the cohort in 1991.

Consumption data showed that 42 percent of the women of child-bearing age ate Lake Ontario fish, and 10 percent reported eating fish for at least seven years, dating back to a time when lake contamination was higher than in recent years. Researchers found a small conception delay for women who ate fish, but the effect was not statistically significant.

The study on the association of fish consumption and length of menstrual cycle, headed by Pauline Mendola, involved data from 2,223 women from the same cohort who reported menstrual-cycle length when they were re-interviewed in 1993. Results showed that eating sport fish from Lake Ontario more than once a month was associated with a menstrual cycle 1.1 days shorter than the cycles of women who did not eat sport fish. Among women who experience regular menstrual cycles, the reduction was half a day.

Mendola said that while these small decreases in menstrual-cycle length are not currently a major public-health concern, the findings may indicate that these environmental contaminants have an effect on hormone production, notably estrogen production, which could have larger implications.