Environmental Contaminants Contribute to Male Infertility
Polychlorinated Biphenyls (PCBs) are no longer commercially produced in the United States, but continue to wreak havoc on our health today. New research published in the journal Environmental Health Perspectives has linked PCBs and other environmental chemicals to sperm abnormalities and male infertility.
Previous studies have found that infertility affects 15% of couples, but that about 50% of male infertility is potentially correctable. Infertility is defined as the inability to conceive after one year of unprotected intercourse.
Melissa Perry ScD MHS, professor and chair of the Department of Environmental and Occupational Health at the George Washington School of Public Health and Health Services, led an observational study on environmental exposure to organochlorine chemicals. The research team studied 192 men who were part of couples that were “sub-fertile” – meaning that they had a lower ability to become pregnant than normal, healthy couples.
Blood was sampled for the presence of chemicals such as PCBs and p,p’-DDE, the main metabolite of the insecticide DDT. Semen samples were taken and assessed for sperm disomy, which occurs when sperm cells have an abnormal number of chromosomes.
All men have a certain number of sperm with such abnormalities, but those with higher levels of PCBs and DDE had significantly higher rates.
Polychlorinated Biphenyl was previously used in products and materials such as transformers, capacitors, and other electrical equipment such as voltage regulators and electromagnets. Other products containing PCBs including cable insulation, adhesives and tapes, oil-based paint, caulking, plastics, carbonless copy paper and floor finish. The EPA banned its use in 1979.
Today, PCBs can still be released into the environment from poorly maintained hazardous waste sites that contain PCBs, illegal or improper dumping of PCB wastes, leaks or releases from electrical transformers and disposal of PCB-containing consumer products into landfills not designed to handle hazardous waste.
DDE (1,1-DICHLORO-2,2-BIS(p-CHLOROPHENYL) ETHYLENE) is a breakdown product of DDT which was banned in the United States in 1972, except in the case of a public emergency. The EPA has classified DDE as a Group B2 probable human carcinogen. Previous animal studies have found that DDE has adverse effects on spermatogenesis and decreased testicular weights.
Human exposure to DDE appears to be primarily through food; levels in the air and water samples are low according to a report from the US Department of Health and Human Services.
“This research adds to the already existing body of evidence suggesting that environmental exposure to certain chemicals can affect male fertility and reproduction. We need to further understand the mechanisms through which these chemicals impact sperm,” said Dr. Perry. “While we cannot avoid chemicals that already persist in the environment, it is imperative that decisions about putting biologically active chemicals into the environment need to be made very carefully, because there can be unanticipated consequences down the road.”
McAuliffe ME, Williams PL, Korrick SA, Altshul LM, Perry MJ, 2011 Environmental Exposure to Polychlorinated Biphenyls and p,p’-DDE and Sperm Sex Chromosome Disomy. Environ Health Perspect doi:10.1289/ehp.1104017
PETER N. KOLETTIS, M.D., University of Alabama at Birmingham, Birmingham, Alabama. Evaluation of the Subfertile Man
Am Fam Physician. 2003 May 15;67(10):2165-2172.
Environmental Protection Agency, Polychlorinated Biphenyl
Environmental Protection Agency, DDE (1,1-DICHLORO-2,2-BIS(p-CHLOROPHENYL) ETHYLENE)