Chemical Technical Summary for Public Health
and Public Safety Professionals
Agency for Toxic Substances and Disease Registry
December 6, 2004
Results of a case-control study in Sweden on subjects between the ages of 30-75 with testicular cancer were evaluated for possible risk involving occupational exposures. Those who were exposed to insect repellents containing DEET for intervals <115 days and >115 days made up two exposure groups. These groups were evaluated by multivariate analysis of exposure. A conditional odds ratio (OR) and 95% confidence interval (CI) were used. An increased risk for testicular cancer was found for those who were exposed to insect repellents, with an OR of 2.3 (95 CI 1.2-4-4) for those exposed for =115 days (n=24 cases). The OR for those exposed <115 days (n=15 cases) was 1.2 (95% CI 0.6-2.5) (Hardell et al. 1998). These data do not necessarily suggest that long-term use of DEET could cause testicular cancer. DEET was not the only chemical substance that the volunteers were exposed to, and the authors of the study note that their findings should be "...interpreted with caution and might be chance findings. Some numbers were based on low numbers of exposed subjects" (Hardell et al.1998).