Health effects of low-dose formaldehyde exposure: a cross-sectional study in occupational settings

To evaluate the health effects of low-dose formaldehyde exposure in occupational settings, focusing on dermatological and respiratory symptoms and the influence of work tenure.

A cross-sectional study was conducted on 414 workers undergoing annual health check-ups at a medical center in Taiwan with 242 individuals categorized as exposed (high exposure [N = 57], low exposure [N = 185]) and 172 as controls. Formaldehyde exposure was assessed through environmental monitoring, with all exposure levels <10% of the permissible exposure limits. Self-reported clinical symptoms, complete blood count (CBC) parameters, and pulmonary function were assessed. Logistic regression analysis was performed to assess exposure-related health effects, adjusting for potential confounders. Tenure was analyzed as both a continuous and categorical variable to assess its impact on health outcomes.

The exposure group reported significantly higher rates of irritationrelated symptoms (9.5% vs. 0.6%, p = 0.009) and skin symptoms (1.7% vs. 0%, p < 0.001) compared to controls. After adjusting for confounders, allergic rhinitis (OR = 16.78, 95% CI: 4.00-70.55, p < 0.001) and allergic dermatitis (OR = 18.83, 95% CI: 2.52-140.56, p = 0.004) remained significantly associated with formaldehyde exposure. No significant differences were found in CBC parameters or pulmonary function between groups.

Even at low exposure levels, formaldehyde was associated with an increased risk of allergic conditions and irritation-related symptoms. While pulmonary function remained unchanged, the higher prevalence of allergic rhinitis and dermatitis suggests potential immune sensitization. These findings emphasize the importance of workplace exposure monitoring and preventive measures. Future longitudinal studies incorporating biomarkers are needed to clarify causal relationships and refine occupational health policies. Int J Occup Med Environ Health. 2025;38(3):236-248.