Impact of occupational phthalate exposure on testosterone levels, and male sexual health questionnaire scores. a dose-response analysis

Tiberiu M. Nita; David Vernez; Sonja Wrobel; Fanny Zufferey; Holger Koch; Pascal Wild; Nancy B. Hopf

doi:10.1530/endoabs.109.P339

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Endocrine Abstracts (2025) 109 P339 | DOI: 10.1530/endoabs.109.P339

SFEBES2025 Poster Presentations Late Breaking (68 abstracts)

Impact of occupational phthalate exposure on testosterone levels, and male sexual health questionnaire scores. a dose-response analysis

Tiberiu M. Nita ^1,2 , David Vernez ^1,2 , Sonja Wrobel ³ , Fanny Zufferey ⁴ , Holger Koch ³ , Pascal Wild ¹ & Nancy B. Hopf ^1,2

Author affiliations

¹Center for Primary Care and Public Health, Unisanté, Lausanne, Switzerland. ²University of Lausanne, Faculty of Biology and Medicine, Lausanne, Switzerland. ³Institute for Prevention and Occupational Medicine of the German Social Accident Insurance (IPA), Institute of the Ruhr-University Bochum, Bochum, Germany. ⁴Service of Clinical Chemistry & Toxicology, Central Institute of Hospitals, Hospital of Valais, Sion, Switzerland.

Background: Phthalates are extensively used in industrial printing. Di-n-butyl phthalate (DnBP) is classified as an endocrine disruptor, negatively impacting testosterone levels in human males. This might contribute to an altered male sexual response, particularly in aging men. The Male Sexual Health Questionnaire (MSHQ) is a validated tool assessing male sexual function across various domains including scores for erectile function (MSHQ-E), sexual activity (MSHQ-S), and a total score (MSHQ-T).

Aim: Evaluate possible dose-response relationships between occupational phthalate exposures and testosterone levels, and MSHQ scores, using age-adjusted statistical models.

Methods: Sixty male printing workers donated urine samples post-shift over five consecutive days and blood samples in the morning on the first and last day of the workweek. Thirty-six urinary phthalate metabolites and serum total testosterone were quantified by liquid chromatography with mass-spectrometry detection and free testosterone by immunoassay. Calculated free testosterone (cFT) and bioavailable testosterone were derived. Dose-response relationships were modeled using multiple linear regressions, while Spearman correlations were used to assess testosterone-MSHQ scores.

Results: Negative associations were observed between cFT and DnBP metabolites; MnBP (β= -0.002, P=0.022), 3-OH-MnBP (β= -0.015, P=0.022), and ∑DnBP (β= -0.002, P=0.019). 3-OH-MnBP was inversely associated with MSHQ-S (β= -1.146, P=0.017). cFT was correlated negatively with MSHQ-E (β=-0.321, P=0.015), MSHQ-S (β=-0.298, P=0.026), and MSHQ-T (β= -0.388, P=0.003). Metabolites of newer-generation phthalates such as DiPeP (MiPeP, 4-OH-MiPeP, ∑DiPeP), DnoP (MnoP, 7-cx-MnHepP), DnHepP (6-OH-MnHepP, 6-cx-MnHepP), and DnPeP (MnPeP, 4-OH-MnPeP) were inversely associated with MSHQ-T.

Conclusion: Occupational exposure to DnBP negatively impacted both hormonal domain and sexual activity, even though recorded concentrations among workers were slightly above those of the general population. The MSHQ total score appears to be a sensitive marker of phthalate exposure. Comprehensive testosterone profiling, combined with clinical scores could be essential for clarifying the impact of endocrine disruptors on reproductive health.