Table 1_Long-term exposure to low concentrations of ambient benzene with incident thyroid dysfunction and the mediating role of accelerated biological aging.docx

Background<p>The associations between ambient benzene exposure and thyroid dysfunction (hypothyroidism and hyperthyroidism), as well as the role of biological aging, remain largely unknown.</p>Methods<p>We included a total of 385,130 participants from the UK Biobank, and Cox regressions were used to assess the association between benzene exposure and incident thyroid dysfunction. We employed restricted cubic splines to fit potential nonlinear exposure–response relationships.

Furthermore, interactions and mediation analyses were conducted to examine the mediating role of biological aging.</p>Results<p>Benzene exposure was dose-responsively associated with an increased risk of thyroid dysfunction, each 1 μg/m³ increase in benzene concentration was linked to hazard ratios (HRs) of 1.19 (95% CI: 1.16, 1.21) for hypothyroidism and 1.21 (95% CI: 1.18, 1.25) for hyperthyroidism. Participants with higher benzene exposure and older biological age showed a greater risk for hypothyroidism compared to those with lower exposure and younger biological age, with a relative excess risk (RERI) of 0.40 (95% CI: 0.13, 0.66).