Researchers found men exposed to DDT and PCBs in their teens had higher rates of abnormal sperm years later.
Lead author Melissa Perry - professor and chair of the Department of Environmental and Occupational Health at the Milken Institute School of Public Health at George Washington University in Washington, DC - and colleagues publish their findings in the journal Environmental Health Perspectives.
In the US, organochlorine pesticides - such as dichloro-diphenyl-trichloroethane (DDT) and polychlorinated biphenyls (PCBs) - were widely used in agriculture and insect control between the 1950s and 1970s.
By the late 1970s, however, such compounds were banned in the US due to overwhelming evidence of the harm they may pose to the environment and animal and human health; they have been associated with increased risk for cancer, developmental delays and endocrine disruption.
Despite these risks, some tropical countries continue to use organochlorines, and even in countries that have banned their use, the chemicals can persist in soil and water for many years. In the US, individuals may be exposed to organochlorines through high consumption of meat, dairy products and fatty fish.
For their study, Perry and colleagues set out to determine how, for the first time, exposure to organochlorines during adolescence may impact sperm quality.
Higher rates of sperm disomy with higher organochlorine exposure
The team assessed the blood and sperm samples of 90 men aged 22-44 who lived in The Faroe Islands, where exposure to organochlorines is higher than normal due to high consumption of fish, including pilot whale meat and blubber.
For 33 of the men, blood samples were also taken at the age of 14, allowing researchers to measure levels of organochlorines and determine their exposure to the pollutants during adolescence, as well as in adulthood.
The researchers used an imaging technique created in Perry's lab to assess the men's sperm samples for signs of sperm disomy, where the sperm cells possess an abnormal number of chromosomes - a condition that has been associated with infertility.
The team found that the men whose blood samples contained higher levels of DDT and PCBs both in adolescence and adulthood had higher rates of sperm disomy than men whose blood samples contained lower levels of the pesticides.
The researchers say their findings support those of a previous study they conducted, which found American men who were part of a couple being treated for infertility and who had higher organochlorine concentrations in their blood were more likely to have sperm disomy.
Pesticide exposure 'may cause reproductive problems years later'
According to the investigators, their findings should prompt policymakers to enforce harsher regulations for the use of pesticides and other chemicals that may pose harm to public health.
"This study, and others like it, suggest that any decisions about putting biologically active chemicals into the environment must be made very carefully as there can be unanticipated consequences down the road," says Perry.
In addition, the team believes their findings emphasize the need for further investigation into how pesticide exposure may affect a man's sperm quality. Perry adds:
"We need more research to find out how these organochlorine pollutants may be affecting the maturation of the testicles and their function. Exposure to these chemicals in adolescence may lead to reproductive problems years later."
In the meantime, the researchers say there are a number of steps individuals can take to reduce their exposure to potentially harmful pesticides, such as reducing intake of foods that are high in animal fats and carefully selecting fish.
The Washington Toxins Coalition recommend checking with state advisories before consuming sport-caught fish or shellfish, as they can be high in DDT and PCBs. Atlantic salmon, wild striped bass, blue crab and American eel are some of the commercial fish that contain higher pesticide levels.
Earlier this year, Medical News Today reported on a study that identified poor sperm quality among men who consumed fruits and vegetables with high levels of pesticide residues.