Occupation and male infertility: glycol ethers and other exposures
- N Cherry1,
- H Moore2,
- R McNamee1,
- A Pacey2,
- G Burgess1,
- J-A Clyma1,
- M Dippnall1,
- H Baillie2,
- A Povey1,
- participating centres of Chaps-UK
- 1 Centre for Occupational and Environmental Health, University of Manchester, UK
- 2 Academic Unit of Reproductive and Developmental Medicine, University of Sheffield, UK
- Nicola Cherry, Community and Occupational Medicine Program, 13-103 Clinical Sciences Building, University of Alberta, Edmonton Alberta, Canada T6G 2G3;
- Accepted 31 January 2008
- Published Online First 16 April 2008
Objectives: To investigate the relation between male infertility and occupational exposures, particularly glycol ethers.
Methods: A case-referent study was designed in which men attending 14 fertility clinics in 11 centres across the UK in 1999–2002 were recruited following 12 months of unprotected intercourse and without a previous semen analysis. Cases were those with low motile sperm concentration (MSC) relative to the time since their last ejaculation (MSC <12×106 for 3 days of abstinence). Referents were other men attending these clinics and meeting the inclusion criteria. A single semen sample was collected at the clinic and analysed at the andrology laboratory serving each hospital. Concentration was determined manually with motility assessed centrally from video recordings. Exposures and confounding factors were assessed from self-completed and nurse–interviewer questionnaires, completed prior to the results of the semen analysis. The occupational histories were assessed for exposures relative to UK norms by a team of occupational hygienists blind to case status.
Results: Of 2118 men in employment at the time of the interview, 874 (41.3%) were cases. Work with organic solvents, particularly glycol ethers, in the 3 months before the first clinic visit was associated with the likelihood of low motile sperm count. Unadjusted odds ratios (OR) for moderate and high glycol ether exposure (compared with none) were 1.70 (95% CI: 1.11 to 2.61) and 2.54 (95% CI: 1.24 to 5.21). Adjustment for potential confounders (surgery to the testes, previous conception, wearing boxer shorts, drinking alcohol, employed in manual work) reduced the risk associated with glycol ether exposure: moderate OR = 1.46 (95% CI: 0.93 to 2.28), high OR = 2.25 (95% CI: 1.08 to 4.69). No other occupational risk factor was identified.
Conclusions: Glycol ether exposure was related to low motile sperm count in men attending fertility clinics. This suggests that, at the time of the study, glycol ethers continued to be a hazard for male fertility.
Funding: The study was funded by the UK Health and Safety Executive, the UK Department of Environment, Transport and the Regions, the UK Department of Health and the European Chemical Industry Council. The views expressed are those of the authors and not necessarily those of the funding bodies.
Competing interests: None.
Ethics approval: Ethical approval was given by the Multi-Centre Ethics Committee for the North West (ref. no. MREC 98/8/73) with subsequent approval given by the Local Research Ethics Committee at each site.
Participating centres of Chaps-UK: Department of Obstetrics and Gynaecology, Queens University, Belfast; Assisted Conception Unit, Birmingham Women’s Hospital; Division of Obstetrics and Gynaecology, St Michael’s Hospital, Bristol; Directorate of Women’s Health, Southmead Hospital, Bristol; Cardiff Assisted Reproduction Unit, University of Wales; MRC Reproductive Biology Unit, Edinburgh; Reproductive Medicine Unit, Liverpool Women’s Hospital; St Bartholomew’s Hospital, London; Department of Obstetrics and Gynaecology, Royal Free and University College, London; Department of Reproductive Medicine, St Mary’s Hospital, Manchester; IVF/Immunology Laboratory, Hope Hospital, Salford; Department of Histopathology, Wythenshawe Hospital, Manchester; International Centre for Life, Newcastle; Department of Obstetrics and Gynaecology, Jessop Hospital for Women, Sheffield; Shropshire and Mid-Wales Fertility Centre, Royal Shrewsbury NHS Trust.