Exposure to organochlorine pesticides in adolescence may alter sperm genetic material and increase the risk of infertility.
Organochlorine pesticides, the main representative of which is the insecticide DDT, were widely used in agriculture and the control of malaria-carrying mosquitoes from the 40s to the 70s. However, due to their toxicity, since the late 60s, many countries began banning the use of DDT in agriculture. Finally, in 2004, an international convention banning the use of this drug to control malaria was signed in Stockholm. Over 170 countries around the world have signed it. However, it is still used in some tropical countries, and in those where it has been used in the past, its derivatives are still present in soil and water. Therefore, people in countries that have banned organochlorine pesticides may still be exposed to them when they consume large amounts of meat, dairy, or fatty marine fish.
In general, organochlorine compounds, which also include polychlorinated biphenyls (PCBs), are used, inter alia, in as industrial plasticizers or an additive to insecticides, they mimic the action of the sex hormones and estrogens. Therefore, they can disrupt the hormonal balance in animals and humans and, consequently, contribute to fertility problems.
The latest study by American scientists, led by Dr. Melissa Perry from the University of George Washington (Washington), showed that contact with these substances not only in adulthood, but also in adolescence, may contribute to abnormalities in the genetic material of sperm and, as a result, impair fertility .
The study included a group of 90 men aged 22-44, residents of the Faroe Islands. People living on them eat a lot of seafood, as well as the meat of marine mammals, which exposes them to higher than average levels of organochlorine pesticides in the body.
Semen and blood samples were collected from all participants in the study. In the case of 40 men, the researchers also had samples of umbilical cord blood (collected at birth) and blood collected at 14 years of age. Using fluorescent DNA probes (FISH method), scientists examined abnormalities in the number of X, Y and chromosome 18 in sperm, while blood was tested for PCBs and DDT derivative (DDE).
It turned out that men who had higher concentrations of both compounds in adulthood much more often had an abnormal number of X, Y and 18 chromosomes in sperm (instead of one, they more often had two copies of the chromosome – the so-called disomy). The higher concentration of DDE and PCB in samples taken at the age of 14 was associated with more frequent occurrence of two copies of the X chromosome or the Y chromosome in sperm.
‘We have shown that exposure to these substances in adolescence can cause future fertility problems,’ Dr Perry emphasizes. Her team found similar results in an earlier study conducted among American men with fertility problems.
According to the researchers, this suggests that organochlorine compounds have a negative impact on the maturation and functioning of the testicles. However, more research is needed to understand the mechanism of their impact on the male reproductive system.
“This study, like other studies like it, indicates that decisions about the introduction of any biologically active compound into the environment should be made with great care as their consequences can be unpredictable,” concludes Dr. Perry.