The former OSHA PEL for vanadium pentoxide dust was a ceiling of 0.5 mg/m3. The Agency proposed a limit of 0.05 mg/m3 as an 8-hour TWA for the respirable dust of vanadium, as vanadium pentoxide, and is establishing this limit today in its final rule. This limit is the same as that recommended by the ACGIH. Vanadium pentoxide is a yellow to rust brown crystalline compound.
Several studies indicate that OSHA's current exposure limit is insufficient to protect exposed workers against vanadium dust's respiratory effects, which include bronchitis, emphysema, tracheitis, pulmonary edema, and bronchial pneumonia. According to Hudson (1964/Ex. 1-880), vanadium is poisonous to all animals by all routes of administration. The LD(50) in rabbits injected intravenously was 1.5 mg/kg, and rats fed 25 ppm demonstrated toxic responses within a short time (Hudson 1964/Ex. 1-880).
Seven cases of upper respiratory tract irritation were reported in boiler cleaners exposed to concentrations ranging from 2 to 85 mg/m3 vanadium pentoxide dust (Sjoberg 1951/Ex. 1-437). Williams (1952/Ex. 1-456) reported eight cases of vanadium poisoning in workers cleaning boilers in an atmosphere ranging from 30 to 104 mg/m3. Gul'ko (1956, as cited by Hudson 1964/Ex. 1-880) observed eye and bronchial irritation in workers exposed to 0.5 to 2.2 mg/m3. A study by Lewis (1959/Ex. 1-345) indicated that workers exposed to levels of 0.2 to 0.5 mg/m3 experienced a higher incidence of respiratory symptoms than did controls. Tebrock and Machle (1968/Ex. 1-446) reported that workers exposed to average concentrations of 1.5 mg/m3 vanadium pentoxide in a mixed dust developed conjunctivitis, tracheobronchitis, and dermatitis. A single average eight-hour exposure to 0.2 mg/m3 respirable vanadium dust caused severe upper respiratory tract irritation in five human volunteers, and two other subjects exposed to a 0.1-mg/m3 concentration also developed delayed cough and an increase in mucous production (Zenz and Berg 1967/Ex. 1-405).
NIOSH (Ex. 8-47, Table N7; Tr. p. 3-99) recommended a ceiling limit of 0.05 mg/m3 for a 15-minute period for this substance. The Workers Institute for Safety and Health (WISH) (Ex. 116, pp. 53) supported NIOSH's recommendation.
In the final rule, OSHA is establishing a limit of 0.05 mg/m 3 as an 8-hour TWA for respirable vanadium dust, measured as vanadium pentoxide. The Agency concludes that this limit will prevent or substantially reduce the risks of eye and bronchial irritation, respiratory symptoms, conjunctivitis, and coughing seen in workers exposed at levels ranging from 0.1 to 2.2 mg/m3. OSHA considers these exposure-related effects material impairments of health.