Objectives: To assess the effect of exposure to hydrogen fluoride (HF) on the airway mucosa in an industrial setting.
Methods: A cross-sectional study encompassing 33 industrial workers in a flame soldering plant and 44 assembly workers unexposed to HF was performed by means of a questionnaire on symptoms and diagnosis regarding upper and lower airways as well as through conduct of a clinical examination of the exposed group. Air concentrations of HF that were monitored in winter amounted to 1.0 mg/m(3) and in summer time to 0.15 mg/m(3).
Results: A threefold risk for epistaxis (RR = 3.6, 95% confidence interval 1.1-11.0) was observed in the exposed group. Time from the start of exposure to HF until debut of a nose bleeding period varied from 1 month to 6 years. Mean induction (latency) time was 42 months. Mean duration of symptoms was 26 months, range 3-72 months, indicating that the exposure level in summer time was sufficient to maintain the propensity of almost daily nose bleeding.
Conclusion: HF is an irritating vapor, even at relatively low air concentrations. We recommend an 8 hr TLV lower than 1.0 mg/m(3).