Harley, KG, AR Marks, A Bradman, DB Barr and B Eskenazi. 2008.
DDT exposure, work in agriculture and time to pregnancy among farmworkers in California.
Journal of Occupational and Environmental Medicine 50(12):1335-1342.
Synopsis by Kim Harley, Ph.D.
Women with potential exposure to pesticides at work or at home took longer to get pregnant than women without pesticide connections.
Pregnant women living in a migrant, farmworker community in California participated in the study. Although all women were pregnant, women who worked in agriculture, lived within 200 feet of agriculture fields or used pesticides in their home took significantly longer to conceive than those who did not have these pesticide exposures.
The findings agree with past studies and add more evidence to this sometimes confusing mix of research outcomes. Many studies have found a relationship between pesticides and male fertility, including effects on sperm health and longer time to pregnancy. However, few studies have examined how pesticide exposure might affect women's ability to get pregnant.
In this study, researchers looked at two types of pesticides: those like DDT that were banned in the 1970s and those currently used in agriculture today.
DDT was measured in the women's blood, but was not associated with women's ability to conceive. DDT levels were quite high because most of the women were Mexican immigrants and DDT was used in Mexico until the year 2000.
However, women who reported occupational exposure to currently-used pesticides were 30 percent less likely to conceive in any given month than women without occupational exposure. Women who reported that pesticides were used in their homes were also less likely to conceive each month compared to those who did not use pesticides.
The predominantly low-income, Latina women participating in the study were very similar except for their pesticide exposures. Nonetheless, the study controlled for other factors that might contribute to these differences in conception, including maternal age, immigration status and history of gynecologic condition.
The researchers asked 402 women about their and their partner's home and work pesticide exposure. They also reported how long it took them to get pregnant -- as measured by the number of menstrual cycles before conception.
Only maternal pesticide exposure was associated with longer time to pregnancy; paternal occupational exposure was not associated with fertility. The authors point out that they only interviewed women who were already pregnant. If infertile couples were included in the study, an even stronger effect of pesticides might be seen.