Occupationally related magnetic field exposure and male subfertility.

Objective: To determine whether there is an association between occupationally related magnetic field exposure, as estimated in milligauss (mG), and male subfertility.

Design: Nested case-control study using three defined case groups and one standard control group.

Setting: Yale New Haven Hospital Infertility Clinic, New Haven, Connecticut. PATIENTS, INTERVENTIONS: Male partners of couples seeking diagnosis and care at the infertility clinic. Men included in the analysis had complete first semen analysis and interview information. Subjects for this investigation consisted of case groups for motility (n = 177), morphology (n = 135), and concentration (n = 172); controls included men normal on all three parameters (n = 304).

Main Outcome Measures: Laboratory confirmation in semen analysis of poor morphology, inadequate motility, and low concentration. Comparisons of occupational magnetic field exposure categories are made between case groups and controls.

Results: The odds of high job exposure category to magnetic fields (> 3 mG [> 0.3 muT]) for morphology cases were odds ratio (OR) = 0.6, for motility cases OR = 1.1, and concentration cases OR = 1.0 as compared with controls. No significant association was demonstrated for medium exposure (> 2 to 3 mG) among all case groups. Multivariate adjustment for selected risk factors did not substantially change estimates of risk.

Conclusions: A lack of association between occupationally related categories of magnetic field exposure and male subfertility, as evaluated by morphology, motility, and concentration, has been demonstrated. These findings do not substantiate theories of deleterious effects to male reproductive health from magnetic fields.