Men in risk of inhaling more polluted air have less sperm, improperly built and with genetic disorders; they also produce less testosterone - showed research of Polish scientists from the Institute of Occupational Medicine in Łódź.
Scientists are not sure exact which mechanism is responsible. "We suspect that air pollution causes an increase in the amount of free radicals in the body, induces so-called oxidative stress, which may reduce the function of the testicles and damage mature sperm, including its genetic material" - explained in an interview with PAP study co-author Dr. Joanna Jurewicz from the Institute of Occupational Medicine in Łódź.
In addition, certain types of air pollution, especially particulate matter, carry particles of hormonally active compounds such as polycyclic aromatic hydrocarbons (PAHs). These compounds interfere with the body\'s secretion of hormones, including testosterone, which regulates spermatogenesis.
In the study, in which specialists from the hospital "Gameta" in Rzgów and the National Research Institute Balice near Kraków also took part, the researchers analysed data of 327 young men (mean age 32 years) who came to a fertility clinic to diagnose the cause of problems with conceiving offspring. Semen, saliva, urine and blood samples were collected.
From the database of the European Environment Agency (EEA) researchers obtained data on air quality and concentrations of various pollutants in places of residence of these men. Researchers focused on the level of particulate matter (particles having a diameter of 10 microns - PM10, and lower diameters), sulphur dioxide, carbon monoxide and nitrogen oxides during the 90 days prior to sampling (spermatogenesis, production of new sperm, takes an average of 74 days). The survey results were published in the journal "Annals of Human Biology" in July 2015.
The analysis included: history of various diseases which may affect the quality of sperm, like mumps, cryptorchidism, testicles trauma or surgery, smoking cigarettes (based on the presence of nicotine metabolite in saliva), other elements of lifestyle and factors affecting men in the workplace.
It turned out that men who were exposed to a higher level all the analysed pollutants in the place of residence had a higher percentage of sperm with abnormal changes. In turn, higher concentrations of particulate matter, carbon monoxide and nitrogen oxides was associated with lower testosterone levels. There were no links between the level of pollution and mobility and numbers of sperm.
In the second paper, the results of which were published in July 2014 in the "Environmental and Molecular Mutagenesis", the same team of researchers demonstrated a link between higher levels of airborne particulate matter with a diameter of 2.5 micrometers (PM2.5), and a higher incidence of sperm with incorrectly duplicated genetic material. It involved the presence of two (so called disomy), instead of one copy of the Y sex chromosome or chromosome 21. In non-smokers but exposed to more air pollution researchers found five times higher incidence of Y chromosome disomy
Leader of the team of scientists Prof. Wojciech Hanke from the Institute of Occupational Medicine in Łódź reminded in an interview with PAP that if a sperm with wrong number of chromosomes fertilizes an egg cell, child may suffer from developmental disorders (for example, the presence of three chromosomes 21 leads to Down\'s syndrome). The specialist noted, however, that the sperm with the wrong number of chromosomes (called aneuploidy) fortunately rarely win in the race to fertilization. In addition, most of the embryos with these disorders do not survive.
"It should be emphasized that in our study we have not tested whether changes in the sperm or testosterone levels translated into lower male fertility. To do this, a different study should be planned" - said Prof. Hanke. He noted that all men had correct, according to the WHO standards, concentration of sperm - from 15 to 300 million per 1 ml of ejaculate.
The problem, however, is that the average concentration of sperm in the semen of men continues to decrease. Because of this, in 2010 WHO dropped lower standard to 15 million per ml, while a decade before it was 20 million per ml. In this situation, any additional disorders of the male reproductive cells are gaining in importance.
"Observing a link in itself does not mean that air pollution in the place of residence of men may lead to changes in the sperm morphology or in the concentration of testosterone. However, the existence of this correlation confirms the need to take action to improve the quality of the air we breathe" - summed up Prof. Hanke.
There is more and more talk recently about high levels of air pollution in many Polish regions and its negative impact on human health, but it is rarely stressed that air quality is also affected by individual decisions taken by each of us, for example on smoking indoors. To raise awareness in this area, the Ministry of Environment has launched a social campaign "We create the atmosphere" which educates about air pollution in the country, its sources and health effects, and how we can contribute to improving air quality in Poland.
PAP - Science and Scholarship in Poland
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