Occupationally related exposures and reduced semen quality: a case-control study.

OBJECTIVE To determine whether there is an association between abnormal semen parameters and occupational exposures to organic solvents, metals, and pesticides. DESIGN Case-control study using three case groups based on different cutoff values for semen parameters and one standard reference group. SETTING University Hospital Utrecht and University Hospital Rotterdam, the Netherlands. PATIENT(S) Male partners of couples having their first consultation at the two infertility clinics (n = 899). INTERVENTION(S) Men provided at least one semen sample. Occupational exposure was assessed with use of job-specific questionnaires, a job exposure matrix, and measurements of metals and metabolites of solvents in urine. MAIN OUTCOME MEASURE(S) Standard clinical semen analyses were used to define case groups and controls. RESULT(S) An association between aromatic solvents and reduced semen quality was demonstrated, irrespective of the exposure assessment method used. The associations were stronger if the case definition was based on stricter cutoff values for semen parameters. Risk estimates were higher if the analysis was restricted to primary infertile men. Exposure to other pollutants at the workplace was not associated with impaired semen quality. CONCLUSION(S) The findings indicated an association between aromatic solvent exposure and impaired semen parameters.