Effects of Organochlorine Compounds on Menstrual Cycles

Gayle C. Windham, Ph.D.
Environmental Health Investigations Branch, Department of Health Services, Oakland, California
R01ES08324

Background: Over the past 20-30 years, environmental health scientists have expressed increasing concern about synthetic chemicals that appear to disrupt hormones in humans and animals. These compounds, known as endocrine disrupters, can cause cancer, birth defects and immune problems and even very small concentrations can interfere with reproduction. In humans, as in animals, hormones are involved in many tasks including energy metabolism, reproduction, growth and development, and virtually every biological process. If synthetic chemicals can disrupt or alter these processes the consequences can be dramatic, hard to diagnose, and possibly irreversible.

Many chemicals with a variety of uses have been proposed to have endocrine disruption potential. The pesticide DDT was one of the first chemicals to be shown to have adverse endocrine effects. In wild birds, especially those high on the food chain, DDT was shown to be the cause of weakened egg shells which caused large drops in the numbers of some species of raptors including the American Bald Eagle. DDT interferes with the deposition of calcium as the developing egg passes through the bird’s uterus. For this and other reasons, it was banned for use in the U.S. in 1972.

Previous research has shown that women exposed to endocrine disruptors at various life stages may have increased risk of disorders and conditions related to hormonal problems such as menstrual cycle irregularities, infertility, endometriosis, autoimmune disorders and cancers of the reproductive system. To add to the body of human data, this group of NIEHS-supported researchers conducted an epidemiologic investigation on a unique population of 50 immigrant women from Southeast Asia expected to have a high exposures to chlorinated pesticides.

Advance: Serum samples from all the women had detectable levels of DDT and its metabolite DDE with mean levels higher than typical of U.S. women. The menstrual cycle length was approximately four days shorter for women with the highest levels compared to the lowest. With each doubling of the serum DDE level, cycle length decreased by a little more than one day. Also, as DDE level increased progesterone metabolite levels decreased. There was no association between PCB levels and changes in cycle length or hormone levels.

Implications: The study results indicate an effect of DDT exposure on ovarian function and menstrual cycle length. These effects could cause problems with fertility, pregnancy, or adverse reproductive conditions. The findings need to be duplicated because of the small size of the study population, but they do suggest that DDT exposure may be an important factor in determining the cause of reproductive problems. These human health effects also have implications for the continued use of DDT or similar compounds in other parts of the world.

Citation: Windham GC, Lee D, Mitchell P, Anderson M, Petreas M, Lasley B. Exposure to organochlorine compounds and effects on ovarian function. Epidemiology. 2005 Mar;16(2):182-90.