[Analysis of liver and lung function status among workers exposed to isocyanates and other occupational hazards]

Objective: To analyze the current status of pulmonary and liver function in workers exposed to isocyanates and other hazardous factors in Shanghai city, and to evaluate the association between occupational exposure and health status. Methods: In February 2025, based on the occupational health examination data from 2013 to 2021 of an occupational health examination institution in the Shanghai occupational health examination database, workers whose hazardous factor exposure records included isocyanates (isocyanates, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate) were selected as study subjects. The pulmonary and liver function at the last examination were analyzed, with the workers grouped by the toxicity of other co-exposed chemicals. Differences in health examination indices among the pre-employment examinees and the on-the-job workers exposed to different types of toxicants were compared using chi-square test, Wilcoxon signed-rank test, Kruskal-Wallis test and Dunn test. The effects of length of service on the health status of the on-the-job examinees were analyzed using multivariate logistic regression and multiple linear regression models. Results: A total of 37875 workers from 192 enterprises were included, including 24362 pre-employment examinees and 13513 on-the-job examinees; among the on-the-job workers, 1312 were exposed to isocyanates only, 9736 were concurrently exposed to hepatotoxic chemicals, and 9830 were concurrently exposed to respiratory toxicants. Compared with the pre-employment examinees, the on-the-job workers concurrently exposed to hepatotoxic or non-hepatotoxic chemicals had lower levels of alkaline phosphatase (ALP) and albumin (ALB), higher rates of hepatic fatty infiltration, fatty liver and abnormal liver B-ultrasound (P<0.001), and the male workers had higher levels of alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), total bilirubin (TBIL) and direct bilirubin (DBIL) (P<0.001) ; the levels of ALP, total protein (TP) and ALB were lower in the workers concurrently exposed to non-hepatotoxic chemicals than in those concurrently exposed to hepatotoxic chemicals (P<0.001). With the increase of length of service, the workers concurrently exposed to hepatotoxic chemicals showed increased levels of ALT, GGT, TBIL and DBIL, decreased levels of ALP and ALB, and increased risks of fatty liver and abnormal liver B-ultrasound (P<0.05), and the risk of abnormal liver B-ultrasound increased in the workers concurrently exposed to non-hepatotoxic chemicals (P=0.002). Compared with the pre-employment examinees, the on-the-job examinees had higher average levels of forced vital capacity as predicted value percentage (FVC%pred), forced expiratory volume in the first second as predicted value percentage (FEV(1)%pred) and FEV(1)/FVC, as well as a higher detection rate of abnormal chest radiographs (P<0.001). The FEV(1)%pred of the workers exposed to isocyanates only was lower than that of the workers concurrently exposed to other toxicants (P<0.001) ; with the increase of length of service, the FVC%pred and FEV(1)%pred of the workers concurrently exposed to other toxicants showed upward trends, while FEV(1)/FVC showed a downward trend (P<0.001) . Conclusion: Slight liver function impairment exists in the on-the-job workers exposed to isocyanates. With the increase of length of service, workers co-exposed to other hazardous factors may have a slight decline in pulmonary ventilation function, and the workers exposed to hepatotoxic chemicals have an increased risk of liver abnormality.