Benzene exposure and health risk assessment among workers in informal footwear workshops: A cross-sectional study in Medan, Indonesia.

Benzene is widely used in small-scale industries, particularly in informal footwear manufacturing, due to its adhesive properties. However, its volatility and carcinogenicity pose serious health risks to workers in poorly regulated environments. This study hypothesized that informal footwear workers in Medan are exposed to benzene concentrations exceeding international safety standards, resulting in measurable biological effects and increased health risks. Environmental monitoring was conducted in seven workshops, revealing ambient benzene levels ranging from 0.101 to 0.5147 mg/m³ . Five locations exceeded the NIOSH Recommended Exposure Limit (0.32 mg/m³), and all surpassed the WHO air quality guideline (0.005 mg/m³). Biomarker analysis showed elevated trans,trans-muconic acid (tt-MA) and malondialdehyde (MDA) levels, particularly in workshops with poor ventilation and high worker density. A moderate correlation between tt-MA and MDA (r = 0.462, p = 0.003) confirmed the link between benzene exposure and oxidative stress. Clinical symptoms such as headache and appetite loss were significantly associated with MDA and tt-MA levels, respectively, suggesting early biological effects. Carcinogenic risk assessment indicated that four locations exceeded acceptable lifetime cancer risk thresholds, with Location VI presenting a 65-fold exceedance. These findings underscore the urgent need for low-cost interventions, such as improved ventilation and safer chemical substitutes, to reduce exposure in informal industrial settings. Longitudinal studies are recommended to clarify causal pathways and inform occupational health policy.