An investigation of the relationship between occupation and male infertility

Aims To test the hypothesis that leather work is associated with male infertility, mediated through the development of oligozoospermia (low sperm concentration). The basis of any association was thought, a priori, to be with exposure to the solvents used in leatherwork.;Methods An unmatched case control study was designed. Interviewer administered questionnaires collected occupational details and other information from 1906 men (88.5% response) who presented with their partners as new referrals for the investigation of infertility in Leicestershire and at Kettering hospital between November 1988 and September 1992. Two sets of comparisons were made. First the Leicestershire infertility presenters were compared as cases to 1013 fathers of control babies from the Leicestershire perinatal mortality survey. Second, a 'within infertility' analysis, restricted to the presenters with infertility, compared the characteristics of those men with oligozoospermia (cases) to those without (controls).;Results The unadjusted odds ratio (OR) for presenting for the investigation of infertility associated with leatherwork was 1.10 (95%CI 0.46, 2.63). The adjusted OR for the development of oligozoospermia associated with leatherwork was 1.20 (95%CI 0.43, 3.35) and there was only a 17% chance that the true relative risk was 2.0 or greater. Adjusted results indicated that leatherwork was associated with only an estimated 6.0% reduction (95%CI -44%, + 55%) in sperm concentration. The adjusted OR for oligozoospermia, low motility and high sperm deformity associated with solvent work were all 1.31 or below and were not statistically significant.;Conclusions There was little evidence to support the hypothesis that leatherwork is a risk factor for oligozoospermia. Overall the findings provide reassurance for the leather industry which uses leather in manufacturing. Further investigation into a possible relationship with high sperm deformity is recommended. The results also suggest that exposure to work with solvents is not a risk factor for oligozoospermia, although less reassurance can be taken from these findings as exposure misclassification is likely to have had an effect.