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Air pollution from traffic or pesticide exposure can significantly damage sperm quality and cause infertility, according to new research.
The meta-analysis of nearly 27,000 studies found that factors such as air pollution or exposure to pesticides or insecticides increased sperm DNA fragmentation by an average of 9.68%.
The researchers, from Semmelweis University in Budapest, Hungary, have called attention to the importance of prevention as men’s reproductive capacity has drastically declined in recent decades.
In two studies examined the Italian region of Campania, known as the Land of Fires, where environmental pollution is high due to the illegal transport of toxic waste and waste incineration was examined.
Another compared data from steel mill workers, and a separate study also looked at police officers helping traffic at a busy intersection.
Other factors assessed by the studies of men in fertility clinics and having a significant impact were smoking, diabetes, testicular tumors and age.
Increased DNA fragmentation from age 50
The research, published in the journal Reproductive Biology and Endocrinology, found that over the age of 50, the integrity of sperm DNA begins to deteriorate significantly.
Dr Zsolt Kopa, head of the Andrology Center in the Department of Urology at Semmelweis University, said: “The so-called DNA fragmentation analysis is currently the only evidence-based test for determining sperm function.
“Examine their DNA content, i.e. the proportion of intact or fragmented genetic material in the sperm. The more fragmented the DNA, the less the sperm’s ability to fertilize. Also, it can increase the risk of miscarriage.
Dr Anett Szabó, PhD candidate and first author of the Semmelweis publication, said: “Based on previous research, we expected that sperm quality would begin to deteriorate significantly after age 40, but our meta-analysis suggests that this age could be much higher.
“We identified a notable increase in DNA fragmentation since age 50, when it increased by an average of 12.58% compared to younger men.
“But, of course, that doesn’t mean it’s worth waiting to start a family, as other important metrics can also deteriorate with advancing age.”
Alcohol does not affect fragmentation
In the current study, the researchers showed that smoking could increase DNA fragmentation by an average of 9.19% compared to non-smokers.
But, in what may be better news, the study evaluating factors leading to decreased fertility suggested that sperm DNA doesn’t tend to deteriorate until after age 50.
Alcohol consumption and body weight also did not play a clinically significant role in the fragmentation of genetic material.
Impaired glucose tolerance was found to lead to an increase in fragmentation of 13.75%, while tumors can also significantly increase DNA fragmentation (by 11.3%).
Some infections, such as chlamydia and HPV, did not affect sperm quality, but bacterial or other sexually transmitted diseases showed increased DNA fragmentation (8.98% and 5.54%).
Varicoceles – dilated veins in the spermatic cord – increase sperm DNA fragmentation by an average of 13.62%.
Fertility rate declining
According to previous studies, the fertility rate in developed Western countries is declining: one in six couples suffer from infertility problems.
The causes are many and about 50% can be attributed to men.
Although the rate of unexplained infertility has decreased significantly in recent decades, in 30% of cases the cause has not yet been identified.
In a separate study, conducted by researchers at the University of East Anglia in collaboration with the Community Empowerment Lab in Lucknow, India, it was found that poor air quality could be linked to reduced mental capacity in younger children. to two years in India.
They warned that, without action, the negative impact on children’s long-term brain development could have life-long consequences.
Lead researcher Prof John Spencer, from the University of East Anglia (UEA), said: ‘Very small particulate fragments in the air are a major concern as they can travel from the airways to the brain.
“Until now, studies have failed to show a link between poor air quality and cognitive problems in children, when brain growth is at its peak and the brain can be particularly sensitive to toxins. Our study is the first to show this association.”
