High levels of air pollution are to blame for a distinct drop in semen quality in Shanghai, according to the doctor who runs the city's main sperm bank.
Sperm donated to the bank at the Ruijin Hospital declined in quality over the last decade, the Shanghai Morning Post reports. Currently, only one-third of the semen is thought to meet the quality standards set by the World Health Organization, with many men suffering low sperm counts or aspermia (the complete lack of sperm).
Zheng Li, who runs the sperm bank, told the newspaper that male infertility was 'increasing year on year' and attributed this decline to worsening environmental factors.
'When the environment is bad, sperm becomes "ugly" and even stops swimming', he said. 'If we don't protect the environment now, mankind will face a worsening infertility predicament'.
According to The Telegraph, the report in the Shanghai Morning Post concluded by 'urging its readers to lead greener lives in order to protect future generations'.
Dr Li previously co-ordinated a study into the effect of the environment on male infertility. Published in 2012, the study reportedly concluded that worsening environmental conditions had mirrored the reduction in sperm quality. His new comments are not supported by any additional study data.
Anecdotally, at least, infertility is on the rise in China. The Telegraph draws on reports from Chinese state news agency Xinhua claiming that China's infertility rate has risen to around 12.5 percent from just three percent two decades earlier, with doctors blaming air pollution, stress, and poor living conditions.
Yet many scientists are sceptical about a link between declining fertility and environmental factors and say that many of the relevant studies are flawed.
The Chinese Academy of Sciences plans to conduct a five-year national study to examine whether environmental pollution may impact women trying to give birth, due to begin in 2014.