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International audience; The associations between urinary phenol concentrations and markers of thyroid function and autoimmunity among potentially susceptible subgroups, such as subfertile women, have been understudied, especially when considering chemical mixtures. We evaluated cross-sectional associations of urinary phenol concentrations, individually and as a mixture, with serum markers of thyroid function and autoimmunity. We included 339 women attending a fertility center who provided one spot urine and one blood sample at enrollment (2009–2015). We quantified four phenols in urine using isotope dilution high-performance liquid chromatography–tandem mass spectrometry, and biomarkers of thyroid function (thyroid-stimulating hormone (TSH), free and total thyroxine (fT4, TT4), and triiodothyronine (fT3, TT3)), and autoimmunity (thyroid peroxidase (TPO) and thyroglobulin (Tg) antibodies (Ab)) in serum using electrochemoluminescence assays. We fit linear and additive models to investigate the association between urinary phenols—both individually and as a mixture—and serum thyroid function and autoimmunity, adjusted for confounders. As a sensitivity analysis, we also applied Bayesian Kernel Machine Regression (BKMR) to investigate non-linear and non-additive interactions. Urinary bisphenol A was associated with thyroid function, in particular, fT3 (mean difference for a 1 log unit increase in concentration: −0.088; 95% CI [−0.151, −0.025]) and TT3 (−0.066; 95% CI [−0.112, −0.020]). Urinary methylparaben and triclosan were also associated with several thyroid hormones. The overall mixture was negatively associated with serum fT3 concentrations (mean difference comparing all four mixture components at their 75th vs. 25th percentiles: −0.19, 95% CI [−0.35, −0.03]). We found no evidence of non-linearity or interactions. These results add to the current literature on phenol exposures and thyroid function in women, suggesting that some phenols may alter the thyroid system. © 2023 by the authors.

International audience; RESEARCH QUESTION: Do heavy metals affect the risk of diminished ovarian reserve (DOR) in women of reproductive age? DESIGN: A total of 139 cases and 153 controls were included between 2016 and 2020. The participants were aged between 18 and 40 years and attended consultations for couple infertility in one of four fertility centres in western France. Cases of DOR were defined as women with an antral follicle count less than 7, anti-Müllerian hormone levels 1.1 ng/ml or less, or both. Controls were frequency matched on age groups and centres, and were women with normal ovarian reserve evaluations, no malformations and menstrual cycles between 26 and 35 days. Heavy metals (lead, mercury, cadmium and chromium) were measured in whole blood at inclusion. Single-exposure associations were examined with multivariable logistic regressions adjusted on potential confounders. Mixture effects were investigated with quantile g-computation and Bayesian kernel machine regression (BKMR). RESULTS: Chromium as a continuous exposure was significantly associated with DOR in unadjusted models (OR 2.07, 95% CI 1.04 to 4.13) but the association was no longer significant when confounders were controlled for (adjusted OR 2.75, 95% CI 0.88 to 8.60). Similarly, a statistically significant association was observed for the unadjusted second tercile of cadmium exposure (OR 1.87, 95% CI 1.06 to 3.30); however, this association was no longer statistically significant after adjustment. None of the other associations tested were statistically significant. Quantile g-computation and BKMR both yielded no significant change of risk of DOR for the mixture of metals, with no evidence of interaction. CONCLUSIONS: Weak signals that some heavy metals could be associated with DOR were detected. These findings should be replicated in other studies.