Epistaxis in a low level hydrogen fluoride exposed industrial staff

To assess the effect of exposure to hydrogen fluoride (HF) on the airway mucosa in an industrial setting.

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).

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.

HF is an irritating vapor, even at relatively low air concentrations. We recommend an 8 hr TLV lower than 1.0 mg/m(3).