Objective  To observe the adverse effect of occupational exposure to hydrogen fluoride on workers' bones.

  Methods  A total of 302 workers occupationally exposed to hydrogen fluoride in a hydrogen fluoride production enterprise and 85 workers in an electronics factory(as control group)were studied. The environmental exposure level and urinary fluoride concentration of the workers were measured, and the bone mineral density, osteoporosis and bone imaging were examined. The relationship between exposure level and bone examination results were analyzed.

  Results  From 2018 to 2020, the average mass concentration of hydrogen fluoride in the air at 30 monitor points of workshops varied from not-detected to 1.867 mg/m³. The calculated workers' external exposure dose of hydrogen fluoride ranged from 0.24 to 133.45 mg. There was no significant difference of urinary fluoride concentration among workers with different genders and ages (P > 0.05). The urine fluoride concentration in the exposure group (1.12 ± 0.95) mg/Lwas higher than that in the control group (0.45 ± 0.14) mg/L(P < 0.01). There was a correlation between urinary fluorine concentration and external exposure dose (R = 0.115, P < 0.05). There were no significant differences of bone loss, osteoporosis and bone imaging abnormality among exposed workers with different external exposure level(P > 0.05). But there was significant difference of the bone loss abnormality among workers with different urinary fluoride concentration (P < 0.05), and the abnormal rate was the highest when urinary fluoride was high as > 1.0-1.5 mg/L. The abnormal rate of bone reduction in exposure group was 38.7%, which was higher than that in control group (4.7%, P < 0.01). There was significant difference of the bone loss abnormality among exposed workers with different age(P < 0.01), and the highest abnormality of bone loss was found in workers younger than 30 years old. There was significant difference of bone loss abnormality among exposed worker with different working time(P < 0.01), and the highest abnormality of bone loss was found in workers with the working time of 1-5 years and/or 5-10 years.

  Conclusion  Occupational exposure to low and medium level of hydrogen fluoride could affect workers' bone mass. The reduction in bone mass was more serious among exposed workers with working time less than 15 years and with higher urinary fluoride levels at 1.0-1.5 mg/L.