A study published by Milken Institute School of Public Health (Milken Institute SPH) at the George Washington University and co-authors has indicated that organochlorines lead to defective sperm. Exposure to these chemicals in teen years and sperm abnormalities are associated with fertility problems later in life. Organochlorine pesticides such as DDT were used extensively through the 1960s and are now banned in the United States but people in the United States can be exposed to these pollutants, by eating a diet with lots of meat, dairy and fatty fish.
“We need more research to find out how these organochlorine pollutants may be affecting the maturation of the testicles and their function,” said lead author Melissa Perry, ScD, MHS, professor and chair of the Department of Environmental and Occupational Health at Milken Institute SPH. “Exposure to these chemicals in adolescence may lead to reproductive problems years later.”
The study was conducted in the Faroe Islands, with 90 men. The population consumes a sea food diet which is rich in organochlorine pollutants including polychlorinated biphenyls or PCBs and the main metabolite of the insecticide DDT. Men with higher levels of the DDT metabolite and PCBs, both as adults and at age 14, had significantly higher rates of sperm disomy.
DDT and other organochlorines linger in water and soil. Exposure may occur on an accumulated basis through the skin or through drinking and eating food containing these pesticides.
“Most people can reduce their exposure to PCBs and DDT by cutting back on foods that are high in animal fats and choosing fish wisely,” Perry said.
The Velsicol Chemical Corporation manufactured pesticides in a community in central Michigan and the town until 1963. DDT has a cumulative effect and is known for accumulating in food webs and persisting for decades in soil and river sediment and banned in the U.S. in 1972. A number of studies have have linked DDT exposure to effects on fertility, immunity, hormones and brain development. Fetuses and young children are most vulnerable to DDT and the major concern is brain development in the womb.
A battle to clean up the contaminated area has has led to a multi-million dollar clean-up effort by Environmental Protection Agency (EPA) and the Michigan Department of Environmental Quality (DEQ), and MIEPA took control of the Velsicol plant as a Superfund site in 1982. In 2006, DEQ sampled yards in a nine-block area near the plant after complaints from residents.
Upon finding DDT in the soil, orange fences were installed around heavily contaminated areas. Six years later the EPA cleaned up those yards, but further sampling found that nearly the entire neighborhood needed remediation. While four of those yards have DDT in excess of human health limits, one has excess polybrominated biphenyls, or PBBs, a flame retardant chemical Velisocol also manufactured and, in 1973, infamously mixed up with a cattle feed supplement, which led to widespread contamination in Michigan.
Thousands of cattle and other livestock were poisoned, about 500 farms were quarantined and people across Michigan were exposed to the chemical linked to cancer, reproduction problems and endocrine disruption.
“Let’s say your backyard has DDT in it. If wind blows, and kicks up dust, you might [be exposed to] DDT. The sun shines, water evaporates, you might get a little DDT,” explains Dr. David Carpenter. “And who knows what other chemical exposure they’re getting from the site.”
In 2014, EPA contractors excavated contaminated soil from 59 yards in the town of 7,000 people, and this summer they will tear up 47 more yards, 10 city-owned properties, the athletic fields at the local high school, and replace St. Louis’ entire water system by tapping into a nearby community’s pipes.
Researchers have also determined that female mice exposed as a fetus were more likely to have diabetes and obesity later in life and causes epigenetic metabolic changes over multiple generations.
Pál Weihe et al. Sperm Aneuploidy in Faroese Men with Lifetime Exposure to Dichlorodiphenyldichloroethylene (DDE) and Polychlorinated Biphenyl (PCB) Pollutants. Environmental Health Perspectives, November 2015 DOI: 10.1289/ehp.1509779