Exposure to fine particles in air pollution may be another factor that affects men’s sperm quality and their fertility.
Cities in China and India have recently been struggling with PM 2.5 pollution levels much higher than is considered safe by the World Health Organization (WHO).
Although the clinical effect may be small, the findings could be important from a public health perspective due to worldwide exposure to pollution.
“Particulate matter contains many toxic chemicals such as heavy metals and polycyclic aromatic hydrocarbons, which have demonstrated harmful to semen quality in laboratory and animal studies,” lead author Xiang Qian Lao said.
Semen quality is significantly related to fertility; men with no (or very few) moving sperm cannot fertilize an egg.
“Sperm shape and size is an important parameter for fertility. Lower percentage/number of normal sperm may cause infertility,” said Lao.
Lao’s team analyzed health exam records and health questionnaires for nearly 6,500 Taiwanese men ages 15 to 49 who participated in a medical examination program between 2001 and 2014.
Semen samples were taken and the men’s sperm quality was assessed for the total sperm number, as well as their size, shape and ability to move.
Researchers found that men’s sperm concentration increased slightly while their risk of abnormally shaped sperm rose by 18 percent with short-term exposure and 26 percent with long-term exposure.
Lao said, “Given the ubiquity of exposure to air pollution, a small effect size of PM 2.5 on sperm normal morphology may result in a significant number of couples with infertility.”
“Thus, global strategies are necessary to minimize the impact of air pollution on reproductive health.”
Although exposure to environmental chemicals has long been considered a potential contributor to infertility, little is known about the effect of air pollution, the study team writes.
The study wasn’t a controlled experiment designed to determine whether or how PM 2.5 pollution may affect sperm.
The study was published in the journal BMJ Occupational and Environmental Medicine.