Study of the effects of occupation and industry on sperm quality.

Most of the environmental exposures known to affect testicular function and/or male fertility are to pharmacologic agents, alkylating agents and antitestosterone agents. There are however, few firmly-based associations with occupational exposure. The aim of this study was therefore to determine if there is any association between different semen parameters (viz. sperm count and motility) in relation to occupations and industrial groupings. A total of 614 subjects who attended an andrology clinic were studied. The investigation included a detailed occupational history, clinical examination and seminal analysis for volume, sperm count, and sperm motility. Each subject's last occupation and the industry he represented was classified according to the standard classification code of the Singapore Standard Occupational Classification (SSOC) and the Singapore Standard Industrial Classification (SSIC), respectively. The results showed that subjects who worked as "plant and machine operators" had a significantly higher risk of oligozoospermia, with an adjusted (for age, smoking, medical history, and testicular size) odds ratio (OR) of 1.93 (1.12-3.30), as compared with other occupational groups. Exposure to excessive heat was a possible factor for the poorer sperm count. "Senior officials and managers" were less likely to have poor sperm count, adjusted OR = 0.52 (0.32-0.84), compared to individuals from other occupations. As for abnormal sperm motility, workers from the "transport and communication" industry had significantly higher adjusted OR of 1.80 (1.08-3.00) when compared to the other occupational groups. This could not be attributed to excessive noise, heat or solvent exposure at the workplace.