Couples with high levels of PCBs and similar environmental pollutants take longer to achieve pregnancy in comparison to other couples with lower levels of the pollutants, according to a preliminary study by researchers at the National Institutes of Health and other institutions.
PCBs (polychlorinated biphenyls) are chemicals that have been used as coolants and lubricants in electrical equipment. They are part of a category of chemicals known as persistent organochlorine pollutants and include industrial chemicals and chemical byproducts as well as pesticides. In many cases, the compounds are present in soil, water, and in the food chain. The compounds are resistant to decay, and may persist in the environment for decades. Some, known as persistent lipophilic organochlorine pollutants, accumulate in fatty tissues. Another type, called perfluorochemicals, are used in clothing, furniture, adhesives, food packaging, heat-resistant non-stick cooking surfaces, and the insulation of electrical wire.
Exposure to these pollutants is known to have a number of effects on human health, but their effects on human fertility-- and the likelihood of couples achieving pregnancy-- have not been extensively studied.
"Our findings suggest that persistent organochlorine pollutants may play a role in pregnancy delay," said the study's first author, Germain Buck Louis, Ph.D., director of the Division of Epidemiology, Statistics, and Prevention Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) at NIH.
Dr. Buck Louis added that individuals may limit their exposure by removing and avoiding the fat of meat and fish, and by limiting the consumption of animal products.
The study was published online in Environmental Health Perspectives and is available online at http://ehp.niehs.nih.gov/2012/11/1204996/ In addition to researchers at the NICHD, the study also included investigators from the Texas A&M Health Science Center, College Station, The Ohio State University, Columbus, Emory University, Atlanta, and The EMMES Corp., Rockville, Md.
To conduct the study, the researchers enrolled 501 couples from four counties in Michigan, and 12 counties in Texas, from 2005 to 2009. The couples were part of the Longitudinal Investigation of Fertility and the Environment (LIFE) study, established to examine the relationship between fertility and exposure to environmental chemicals and lifestyle. An earlier analysis from the LIFE study found that high blood levels of lead and cadmium also were linked to pregnancy delay.
The women taking part in the study ranged from 18 to 44 years of age, and the men were over 18. Couples provided blood samples for the analysis of organochlorines (PCBs) and perfluorochemicals (PFCs). Women kept journals to record their monthly menstrual cycles and the results of home pregnancy tests. The couples were followed until pregnancy or for up to one year of trying.