Risk Assessment for Phosphorus Tribromide
Abstract
Phosphorus tribromide (PBr3) has effective fire fighting properties which make it a possible replacement tor Halon 1301. Results of genotoxicity testing using bacterial Salmonella strains indicted PBr3 is not a mutagen for either frame shift or base-pair substitution tester strains in both buffered and unbuffered solutions. Acute aquatic toxicity testing determined a 96-hour LC50 value for fathead minnows at 71 mg/L (25 mg/L NOEC) and a 48-hour EC50 value for Daphnia magna at 22.6 mg/L (6.25 mg/L NOEC). Application of 10 ul neat PBr3 to intact skin of an anesthetized NZW rabbit caused edema and necrosis of the treated skin within 10 minutes of dosing. Toxicity was not observed in rats exposed for 4 hr to 0.4 mg/L in an inhalation exposure. Male rats (5/group) were exposed to PBr3 vapor, 4 hr/d for 5d, at 0, 0.06, 0.16 and 0.51 mg/L PBr3; 0.06 mg/L was the NOAEL. Rats (10/sex/group) were exposed to PBr3 vapor, 4 hr/d, 5 d/wk, for 4 wk at 0, 0.03, 0.01 and 0.3 mg/L; the NOAEL was 0.1 mg/L. Phosphorus tribromide reacts with moisture in the air to produce phosphonic acid and hydrogen bromide gas (HBr). A 10 cc cartridge of PBr3, tested as fire suppressant, would react to form an estimate 25 g of HBr. If uniformly distributed in a room 10x10x5 m in size, the maximum HBr concentration would be 0.05 mg/L (50 mg/in3); if in a 61.5x46.2x14.8 m hanger, it would be 5.9x10-4 mg/L (0.59 mg/ni3). Since the exposure limit for HBr is 10 mg/m3, the maximal hanger concentration would be below the action level, indicating that an acceptable exposure level during usage on aircraft is possible based on the physical characteristics of PBr3 and the small amount necessary for fire suppression. Dermal and eye contact with PBr3 should be avoided due to its corrosive behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1998
- Accession Number
- ADA384692
Entities
People
- D. E. Dodd
- D. R. Mattle
- P. D. Haaland
- R. E. Wolfe
- T. R. Sterner