Pesticide Use and Menstrual Cycle Characteristics Among Premenopausal Women in the Agricultural Health Study

Abstract

Some pesticides are known, or suspected, to have hormonal or ovotoxic effects that could compromise reproductive function. Certain pesticides reportedly alter the estrous cycle in animals. If exposure to pesticides does have adverse effects, changes in the menstrual cycle might influence fecundability and the risk of hormone-related disorders. The Agricultural Health Study is a prospective cohort investigation of commercial and private pesticide applicators and the spouses of private applicators, mainly farmers. Associations between pesticide use and menstrual function were sought in 3103 women who lived on farms in Iowa and North Carolina. The women, 21 to 40 years of age, were premenopausal, were not pregnant or breast feeding, and were not taking oral contraceptives. Self-administered questionnaires dealing with pesticide use and reproductive health were completed at the time of enrollment in the years 1993-1997. The lifetime use of any pesticide and the use of hormonally active pesticides were of particular interest. Apparent associations between pesticide use and features of the menstrual cycle (cycle length, missed periods, intermenstrual bleeding) were controlled for age, body mass index, and current smoking status. Approximately 57% of women reported having mixed or applied pesticide. A majority had done so for 1 to 9 days per year. One third of women had applied hormonally active or ovotoxic agents. Mixing or applying any type of pesticide at any time was associated with increased cycle length and also with fewer reports of missed periods. Days of pesticide use tended to correlate with an increased chance of having long cycles and missed periods. Working in the fields correlated with missed periods in women who had never mixed or applied pesticides. The use of carbamate pesticides was associated with an increased chance of long cycles and with a lesser risk of irregular cycles. Herbicide use correlated with a lower likelihood of short cycles and irregular periods, and with a higher chance of missed periods. The use of fumigants was associated with an increased likelihood of short cycles and with missed periods. Whatever associations were found persisted after controlling for work-related physical activity. These findings, along with reported toxicologic studies, suggest that using certain hormonally active pesticides may alter menstrual cycles.