1. National Center for Occupational Safety and Health, National Health Commission of the People’s Republic of China, Beijing 102308, China
2. National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
3. National Research Institute for Family Planning and WHO Collaborating Centre for Research in Human Reproduction, Beijing 100081, China
4. National Health Commission Key Laboratory of Male Reproductive Health, Beijing 100730, China