Air pollution can affect sperm quality, especially sperm flow – the ability of sperm to swim where it should – according to a new study analyzing the sperm of more than 30,000 men in China.
The study, published today in JAMA Networks magazine, also suggested that the smaller the size of the pollutants, the greater the link and the worse the quality of the sperm.
“Our findings suggest that particles of small particle size may be significantly stronger than larger particles in creating sperm malformations,” wrote the authors of the paper. Researchers believe that these findings highlight another reason for the need to reduce exposure to air pollution among men of childbearing age.
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Researchers have long been trying to determine whether there is a link between air pollution and sperm quality, but it is still unclear whether the former has negative effects on men’s health because the results from the studies are often inconsistent and complex to put it in the right place. There seems to be a reason to believe that pollution can have a detrimental effect on reproductive health in the general population, as evidenced by this review of international literature published in December 2021.
Researchers at Tongji University Medical School in Shanghai looked at data records from 33,876 men from 340 Chinese cities, with an average 34 years of age, with varying degrees of air pollution among themselves, and their wives getting assisted. reproductive technology for their sperm between January 2013 and December 2019.
They then looked at patterns between sperm quality about whether participants were exposed to particles smaller than 2.5 micrometres, between 2.5 and 10 micrometres, and 10 micrometres, at various critical times 90 days before the visit. to them. at the hospital to ejaculate. To determine sperm quality, researchers focused on factors such as sperm count, concentration, and sperm flow.
Although researchers have not been able to find a significant link between air pollution and sperm quality depending on sperm count or concentration – they have found that when a participant is exposed to small particles, there is a decrease in both continuous and complete sperm flow. . Progressive sperm motility is the ability of sperm to swim forward, while full sperm movement refers to the ability of sperm to swim normally.
In particular, when exposed to particles smaller than 2.5 micrometres in diameter. there was a moderate decrease in sperm flow by 3.6%, while when particles of 10 micrometres were exposed, there was 2.44% less sperm movement. This means that particles of different particles may have different effects on sperm quality, perhaps because the smaller the particle, the more likely it is to penetrate deep into the human lungs.
The data show that the effects of pollution are most pronounced when exposure occurs during the first 90 days of sperm production – the so-called spermatogenesis – than the other two stages. This, in turn, could mean that particle matter affects sperm at the genetic level, according to researchers, but this is just speculation, and there is more research to be done in this area.
“The possibility of a link between air pollution and sperm quality has been raised in many studies over the years, although not everyone agrees with this conclusion,” said Allan Pacey, a professor of andrology at the University of Sheffield, who said. was not involved in the study. “This paper adds to the evidence that the link is real, and is amazing because we use sperm quality data on more than 30,000 men.”
“But the rate of decline in sperm flow seems very low,” Pacey said, emphasizing that intercourse is not the cause. He noted that the paper failed to provide any information about morphology, morphology and sperm size, making it difficult to determine if contaminants could be the cause of sperm degeneration and that is why their flow was reduced, even if there were other reasons. .
According to Pacey, it is important to take these findings with a little salt. Although the data suggest that contamination may have a negative impact on sperm flow, there is still insufficient information to determine whether this could have a significant clinical impact, and result in a general decline in men’s ability in highly contaminated areas. that they may be fathers. Further research in the field could help answer that question with greater certainty in the future.