Exposure to organochlorines during the teen years may lead to defective sperm associated with infertility later in life, a small-scale George Washington University study finds.

In the 1940s, organochlorines were introduced as pesticides in the United States and used extensively through the 1960s; while most of these chemicals are banned now, they have persisted in the environment — and our bodies. To understand their possible medical effects, Dr. Melissa Perry, chair of the department of environmental and occupational health at Milken Institute School of Public Health, led a research team to study blood and sperm samples taken from 90 men living in The Faroe Islands. This island community, located in the North Atlantic, consumes whale meat, blubber, and a generally seafood-rich diet. This atypical eating style leads to higher-than-average exposures to organochlorine pollutants, including PCBs and DDT (polychlorinated biphenyls and dichlorodiphenyltrichloroethane).

For the study, the team measured the amount of organochlorine pesticides in blood samples taken from all the men. Next, the team used a special imaging technology to examine the men’s sperm for an abnormal number of chromosomes, a condition known as disomy. Importantly, the research team also had access to blood samples of 33 participants taken at age 14. Conducting tests and analysis, the researchers derived unsurprising results.

Results of the Analysis

Men with higher levels of DDT and PCBs in their blood samples, both as adults and at age 14, had significantly higher rates of sperm disomy, the researchers discovered. Importantly, an abnormal number of chromosomes is thought to contribute to up to 50 percent of early pregnancy losses.

“The results reported here further demonstrate links between organochlorine exposures and sperm abnormalities and illustrate that the impacts of persistent pollutants on testicular maturation and function need deeper investigation,” concluded the researchers.

The U.S. has banned or severely limited the use of organochlorines; however, not all countries have done the same and at the same time these chemicals linger in the soil and water.

"In the general U.S. population, food, particularly meat, fish, and dairy products, continues to be the primary source of DDT exposure," stated a Centers for Disease Control and Prevention report, which noted that "intakes have decreased over time." DDT can be absorbed after ingestion, inhalation, or skin exposure.

Chlordane and heptachlor were once used to kill termites and other insects on agricultural crops, lawns, buildings, and soil in the U.S. Both of these pesticides are persistent and have been detected in water from agricultural run-off and near production and disposal facilities, according to the CDC. Heptachlor and chlordane accumulate in fatty animal tissues (meat, fish, and dairy products). Both chemicals can also cross the placenta and are excreted into breast milk.

Source: Perry M, Young HA, Grandjean P, et al. Sperm Aneuploidy in Faroese Men with Lifetime Exposure to Dichlorodiphenyldichloroethylene (DDE) and Polychlorinated Biphenyl (PCB) Pollutants. Environmental Health Perspectives. 2015.