How Pollution Can Affect Fertility In Men

Air pollution - particularly levels of fine particulate matter - may affect sperm quality and lead to infertility in men, a study has warned. Environmental exposure to chemicals is thought to be a potential factor in worsening sperm quality, but the jury is still out on whether air pollution might also have a role. To explore this possibility further, researchers from Chinese University of Hong Kong looked at the impact on health of short and long term exposure to fine particulate matter (PM2.5) among nearly 6,500 15 to 49 year old men in Taiwan.

Dr Pushpa Chandra explains this. She says, "Whatever we breathe, we take a lot of toxins in our body through that. So lack of oxygen and more of toxins in the blood stream makes it impure. Due to this we may end up with a lot of diseases in the long run."

The men were all taking part in a standard medical examination programme between 2001 and 2014, during which their sperm quality was assessed. PM2.5 levels were estimated for each man's home address for a period of three months, as that is how long it takes for sperm to be generated, and for an average of two years, using a new mathematical approach combined with NASA satellite data. A strong association between PM2.5 exposure and abnormal sperm shape was found.

Every five microgramme per cubic metres increase in fine particulate matter across the two year average was associated with a significant drop in normal sperm shape/size of 1.29 per cent.

It was associated with a 26 per cent heightened risk of being in the bottom 10 per cent of normal sperm size and shape, after taking account of potentially influential factors, such as smoking and drinking, age or overweight.

"Females may end up with a lot of diseases. In terms of fertility, air pollution degrades the quality of ovum. However, in men, due to habits like drinking and smoking sperm count decreases. Exposure to pollution decreases their sperm motility. The proportion of defective sperms may increase much higher than average. So the chances of developing infertility is high," Dr Chandra added. 

However, it was also associated with a significant increase in sperm numbers, possibly as a compensatory mechanism to combat the detrimental effects on shape and size, researchers said.

Similar findings were evident after three months of exposure to PM2.5.

This is an observational study so no firm conclusions can be drawn about cause and effect, and the researchers were not privy to information on any previous fertility problems. Exactly how air pollution could impair sperm development is not clear. How many of the components of fine particulate matter, such as heavy metals and polycyclic aromatic hydrocarbons, have been linked to sperm damage in experimental studies, researchers said.

Free radical damage, brought on by exposure to air pollutants, might have a possible role, as this can damage DNA and alter cellular processes in the body, they said.

"Although the effect estimates are small and the significance might be negligible in a clinical setting, this is an important public health challenge," said Xiang Qian Lao of the Chinese University of Hong Kong.

"Given the ubiquity of exposure to air pollution, a small effect size of PM2.5 on sperm normal morphology may result in a significant number of couples with infertility," Lao said.

For preventive measure, Dr Chandra says, "There is not much that you can do to protect yourself in this polluted environment. For men who work in factories and in industrial areas and construction sites fort that matter, protecting oneself against pollution is not easy."

"People must avoid going out too often like for a walk. But for people who are working, it is very difficult to stay safe. The masks available can also not provide you with much protection, we cannot be sure how effective they are. When pollution levels are too high, not much can be done but avoiding going out too often." 

(Dr Pushpa Chandra is a Gynaecologist)