Analysis of hazard monitoring results of occupational manganese-exposed workers in Guangxi 2019-2022

Objective To understand the exposure levels of manganese and its inorganic compounds among workers in manganese-related enterprises in Guangxi and to provide a basis for the prevention of occupational manganese hazards.

Methods Data on the monitoring results of manganese and its inorganic compounds, occupational health examinations of manganese-exposed workers, and basic information about enterprises reported in Guangxi from 2019 to 2022 were collected from the data bank of the Occupational Disease Hazard Factors Monitoring System of the Chinese Center for Disease Control and Prevention.

Results From 2019 to 2022, occupational hazards of manganese were monitored in 768 enterprises, including 1 252 testing points (worksites or workers). The manganese level at 77 worksites, with an exceedance rate of 6.15%, was higher than the national occupational exposure limit, the highest in 2020. The median concentration-time weighted average of manganese and its inorganic compounds was 0.013 (0.003 to 0.050) mg/m³. The major monitoring work was done in 2022, the year with the largest number of testing enterprises and testing points. And the data showed that non-compliance worksites were mainly in the automobile manufacturing industry (exceedance rate of 9.46%). The non-compliance rates and manganese exposure levels among enterprises with different scales and economic types showed no statistically significant differences (both P > 0.05). However, the differences among enterprises with different industries, working hours, and locations were significant (all P < 0.001), with the highest rate in the automobile industry, enterprises with longer working hours than 8 hours, and in Guigang City. The rate of occupational health examinations from 2019 to 2022 was 65.16%, with an abnormality of 2.78%. The differences in examination rates and abnormal rates over these four years were statistically significant (both P < 0.001), with the lowest examination and abnormal rates in 2022 and the highest in 2020.

Conclusions The airborne manganese exposure levels in most workplaces in Guangxi were lower than national standards, and the rate of occupational health examinations was not high. Special attention should be paid to the automobile manufacturing industry and the enterprises in Guigang City.