SODIUM BISULFITE
OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.
CAS: 7631-90-5; Chemical Formula: NaHSO3
OSHA’s Z tables previously included no exposure limit for sodium bisulfite. The Agency proposed to establish a limit of 5 mg/m3 as an 8-hour TWA, and it is establishing this PEL in the final rule. NIOSH (Ex. 8-47, Table N1) agrees with the selection of this limit, which is the same as that recommended by the ACGIH. Sodium bisulfite is a white crystalline powder and has an odor like that of sulfur dioxide.
The oral LD(50) in rats fed this substance is 2 g/kg (Dow Chemical Company 1977d, as cited in ACGIH 1986/Ex. 1-3, p. 534), and the intraperitoneal LD(50) for rats is 115 mg/kg (Hoppe and Goble 1951/Ex. 1-490). The ACGIH reports that sodium bisulfite is an eye, skin, and mucous membrane irritant; acute exposures have resulted in mild eye and respiratory effects (ACGIH 1986/Ex. 1-3, p. 534).
One rulemaking participant, Mr. Gary Melampy of the Independent Lubricant Manufacturers Association (ILMA), remarked that OSHA’s discussion of the proposed limit for sodium bisulfite in the preamble failed to demonstrate an adequate basis for the limit. OSHA notes that dose-response data to demonstrate a no-effect level are lacking. The 5-mg/m3 limit was proposed because it represents a limit below that established for physical irritant particulates, and this limit reflects the irritant properties of sodium bisulfite. In the professional judgment of the ACGIH (1986/Ex. 1-3, p. 534), “inhalation of or contact with the dust would result in high local concentrations [of sodium bisulfite] in contact with high local concentrations of sensitive tissue.” The ACGIH further states that an occupational limit below that for physical irritant particulates “seems definitely in order.” OSHA concurs with this assessment.
Dr. Grace Ziem, an independent occupational physician (Ex. 46), expressed concern about the adverse effects of sodium bisulfite on sensitized individuals. Although cases of severe, and even lethal, allergic reactions to this material have been documented from the use of sodium bisulfite as a food additive, OSHA does not believe that there is sufficient information to use as a basis for an exposure limit to protect against inhalation-induced allergic reactions.
OSHA finds that exposure to this substance presents a significant risk of irritant effects at high concentrations, and that these effects constitute material impairments of health. Accordingly, to substantially reduce this risk, OSHA is establishing a 5-mg/m3 8-hour TWA for sodium bisulfite.