Occupational exposure to organic solvents and the risk of developing testicular germ cell tumors (TESTIS study): Effect of combined exposure assessment on risk estimation.

OBJECTIVES: Etiological factors of testicular germ cell tumors (TGCT) remain largely unknown, but a causal role of occupational exposures to solvents has been suggested. Previous studies analyzing these exposures reported discordant results, potentially related to exposure assessment methods. The aim of this study was to investigate the role of occupational exposure to solvents on the risk of developing TGCT among young men. METHODS: This study examined occupational exposures to solvents and TGCT risk based on the lifetime work histories of 454 cases and 670 controls, aged 18-45 years, of the French national TESTIS case-control study. Solvent exposure was estimated using: (i) exposure assignment by job-exposure matrix (JEM) and (ii) JEM combined with self-reported exposure data from specific questionnaires (SQ) and expert assessment (EA). Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression models. RESULTS: Both approaches (JEM and JEM+SQ+EA) showed a consistent association between TGCT and trichloroethylene exposure (exposed versus not exposed; JEM=OR 1.80 [95% confidence interval (CI) 1.12-2.90] and JEM+SQ+EA= OR 2.59 (95% CI 1.42-4.72). Both approaches also observed positive associations with ketone esters and fuels & petroleum-based solvents. CONCLUSION: The results suggest that some organic solvents might be involved in the pathogenesis of TGCT among occupationally exposed men. The combined use of JEM+SQ+EA seemed to limit misclassification by considering individual exposure variability and is, therefore, an appealing approach to assess occupational exposures in epidemiological studies.

Comparison of embryo morphokinetics after in vitro fertilization-intracytoplasmic sperm injection in smoking and nonsmoking women.

OBJECTIVE: To evaluate the impact of female smoking on early embryo development in vitro using a time-lapse system. DESIGN: Retrospective analysis of prospectively collected database. SETTING: Assisted reproductive technology (ART) program. PATIENT(S): A total of 135 infertile couples undergoing IVF-intracytoplasmic sperm injection (ICSI) cycle. INTERVENTION(S): Embryo culture in a time-lapse incubator (Embryoscope, Unisense Fertilitech). MAIN OUTCOME MEASURE(S): Embryo morphokinetic parameters. RESULT(S): Of 135 women, 139 and 729 oocytes were cultured in 23 smokers and 112 nonsmokers, respectively. Basal characteristics and ovarian stimulation parameters were comparable in both groups. Serum antimüllerian hormone level and antral follicle count were significantly lower in smokers than in nonsmokers. Conventional embryologic parameters were comparable in both groups, but time-lapse analysis showed that most cleavage events occurred significantly later in smokers than in nonsmokers, leading to poor cycle outcome in smokers. CONCLUSION(S): Female smoking impairs early embryo development, as reflected by time-lapse analysis. This might contribute to the dramatic decrease in pregnancy rates (PRs) in smokers undergoing IVF. Time lapse is a useful tool for the identification of deleterious components impairing early embryo development.