OSHA formerly had a limit of 1 mg/m3 for ferrovanadium dust. The ACGIH has a TLV-TWA limit of 1 mg/m3 with a TLV-STEL of 3 mg/m3; the NIOSH-recommended exposure limit for metallic vanadium is 1 mg/m3 as a 10-hour TWA. The proposed PEL was 1 mg/m3, with a STEL of 3 mg/m3. NIOSH (Ex. 8-47, Table N1) concurred with these limits, which are established by the final rule. Ferrovanadium dust exists as dark, odorless, solid particles.
Soviet studies in animals showed ferrovanadium dust to be less toxic than vanadium pentoxide. Roshchin (1952/Ex. 1-1166) reported that no acute intoxication occurred in animals exposed to ferrovanadium dust at concentrations as high as 10,000 mg/m3; however, serious chronic pulmonary changes were observed after short-term exposures (one hour) on alternate days for two months to concentrations in the 1000- to 2000 mg/m3 range. These pulmonary changes consisted of chronic bronchitis and chronic lung inflammation. Only NIOSH commented on this substance.
OSHA is establishing a PEL of 1 mg/m3 TWA and a STEL of 3 mg/m3 for ferrovanadium dust to reduce the significant risk of chronic pulmonary damage shown to be associated with exposures to this substance at the elevated short-term levels formerly permitted by the TWA limit alone. OSHA considers the pulmonary damage caused by exposure to ferrovanadium dust to be material impairments of health. The Agency concludes that the combined TWA limit and STEL will substantially reduce this risk.