Exposure to benzene, toluene and xylenes (BTX) and biological aging: epidemiological evidence from Chinese industrial workers and mechanistic insights

Benzene, toluene and xylenes (BTX) are common workplace volatile organic compounds, but evidence linking BTX exposure to biological aging is limited. We examined associations between urinary BTX metabolites and biological age acceleration, and explored biological plausibility using computational analyses (network toxicology and molecular docking). We enrolled 301 BTX-exposed workers and 741 unexposed controls (Henan, China, 2022-2023), and selected 301 matched controls using 1:1 propensity score matching. Biological age was estimated with the Klemera-Doubal method (KDM) from clinical biomarkers, and biological age acceleration (KDM-BA.Accel) was defined as biological age minus chronological age. Creatinine-adjusted urinary metabolites of benzene (S-phenylmercapturic acid [SPMA] and trans, trans-muconic acid [TTMA]), toluene (S-benzylmercapturic acid [SBMA]) and xylenes (2-methylhippuric acid [2MHA] and 3-/4-methylhippuric acids [3&4MHA]) were analyzed using generalized linear models, and mixture associations were assessed with Bayesian kernel machine regression (BKMR). In fully adjusted models, higher SPMA (β = 0.15, 95% CI: 0.07 to 0.24) and TTMA (β = 0.08, 95% CI: 0.01 to 0.14) were associated with higher KDM-BA.Accel, and xylene metabolites also showed positive associations. BKMR suggested a positive overall association of the BTX mixture with KDM-BA.Accel, with SPMA and TTMA contributing most prominently. Network toxicology prioritized eight hub genes (TP53, TNF, NFKB1, TGFB1, MAPK3, CTNNB1, FOS and JUN), and enrichment analyses were consistent with oxidative stress response, inflammatory signaling, and cell-cycle regulation pathways. Overall, higher urinary BTX metabolites, particularly benzene biomarkers SPMA and TTMA, was associated with higher biological age acceleration. Future work should include prospective cohorts with repeated biomonitoring and experimental studies to validate the associations and test the implicated mechanisms.