Chemicals Can Influence Menstrual Cycles

Using women's stored blood samples from the 1960s,researchers determined that exposure to polychlorinatedbiphenyls (PCBs) may impact women's menstrual cycles.

PCBs were once used for a range of industrial and householdproducts. They were banned in the United States in the late1970s because of cancer risks. Yet, PCBs remain in the environmentand accumulate in the fatty tissue of animals.

The exposure to the chemicals continues mainly through diet,such as consumption of contaminated fish. The researchers alsosaid that some PCBs are thought to act as endocrine disrupters.Reporting in Epidemiology (March 2005), Glinda S. Cooper,PhD, said that the possible health consequences with humansare not fully understood.

The study involved >2300 women who were all pregnantwhen their blood samples were taken. The researchers foundthat women with higher blood PCB levels had a history of moretime between monthly periods. The difference in cycle lengthbetween women with the highest and lowest PCB levels wasequal to <1 day. The participants who fell into the high-PCBgroup also were more likely to have irregular periods.