Environmental pollution can cause infertility. However, men and women are affected by different factors, Danish scientists report. TASR informs based on reports from the scientific journal BMJ and The Conversation portal. More than half of the planet’s population lives in urban areas, but at the same time approximately every sixth person suffers from infertility. Danish scientists therefore decided to investigate the long-term impact of noise and air pollution on men and women of reproductive age.
Previous research has shown the adverse effect of pollutants not only on the environment, but also on the human body, where they can cause various types of cancer and cardiovascular diseases. After inhalation, they can penetrate into the blood and from there into the whole body, including the reproductive system, where they can damage eggs and sperm.
The effect of noise has not yet been investigated in as much detail as the effect of chemicals. According to some studies, noise can increase the level of stress hormones (such as cortisol) in the blood. Danish researchers studied people of reproductive age who are likely to try to have children, therefore, they may be at risk of infertility. For this, they used data from several national databases of Denmark, where they are stored throughout a person’s life. The results of the study were published in the scientific journal BMJ in September.
According to the database, there are more than two million Danes of reproductive age. The researchers therefore narrowed the selection down to persons aged 30 to 45 who live in a shared household or are married, have fewer than two children and lived in Denmark from January 1, 2000 to December 31, 2017. Persons with infertility diagnosed before the age of 30 and persons living alone or in a registered homosexual partnership were excluded from the study. Persons with incomplete information, such as a missing address, were also excluded from the study. The resulting cohort consisted of 377,850 women and 526,056 men meeting the established criteria.
The authors of the study did not contact the person directly, but over the next five years tracked their whereabouts and whether they had been diagnosed with infertility. At the same time, based on the residence address, they estimated exposure to noise and pollutants – solid particles with a diameter of up to 2.5 micrometers (PM2.5). According to the results of the study, infertility was found in 16,172 men (out of 526,056) and 22,672 women (out of 377,850).
The study further states that men exposed to 1.6 times the level of PM2.5 as recommended by the World Health Organization (WHO) run a 24 percent higher risk of infertility. Women over 35 exposed to traffic noise 10.2 decibels higher than average (55 to 60 decibels) threatens a 14 percent higher risk of infertility.
The risks of infertility were comparable in urban and rural areas, even after taking into account other criteria such as education or income. According to its authors, the study emphasizes the immediate and long-term effects of the environment on people and the different ways in which it can affect women and men.
However, research using databases also has its pitfalls – scientists often had to make assumptions. One is, for example, the assumption that did the subjects really try to conceive a child, although they didn’t have to try. Another is the assumption that they were staying at their permanent address, even though they may have actually lived elsewhere. This is the largest study to date and an important step in the discovery of the potential link between air pollution, traffic noise and infertility. However, for a better understanding of this issue, more detailed studies based on exact, not estimated values, which also take into account other factors, are needed.
