Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 100–63–0
NIOSH REL: 0.14 ppm (0.6 mg/m3) 2-hr CEILING [skin]; NIOSH considers phenylhydrazine to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].
Current OSHA PEL: 5 ppm (22 mg/m3) TWA [skin]
1989 OSHA PEL: 5 ppm (20 mg/m3) TWA, 10 ppm (45 mg/m3) STEL [skin]
1993-1994 ACGIH TLV: 0.1 ppm (0.44 mg/m3) TWA [skin], A2
Description of substance: Colorless to pale-yellow liquid or solid (below 67°F) with a faint, aromatic odor.
LEL:. . Unknown
Original (SCP) IDLH*: 295 ppm [*Note: "Effective" IDLH = 250 ppm -- see discussion below.]
Basis for original (SCP) IDLH: No data on acute or chronic inhalation toxicity are available on which to base the IDLH. Systemic effects described by Patty  were caused by chronic exposures from oral dosing. NIOSH  cited a rat oral LD50 of 188 mg/kg [Ekshtat 1965] which provides a calculated estimate of 1,300 mg/m3 (295 ppm) for the IDLH. Because of the assigned protection factor afforded by each device, however, 50 ´ the OSHA PEL of 5 ppm (i.e., 250 ppm) is the concentration above which only the "most protective" respirators are permitted.
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal dose data:
|Species||Reference||Route||LD50 (mg/kg)||LDLo (mg/kg)||Adjusted LD||Derived value|
|Ekshtat 1965 |
|293 ppm |
|29 ppm |
Human data: None relevant for use in determining the revised IDLH.
|Revised IDLH: 15 ppm |
Basis for revised IDLH: No inhalation toxicity data are available on which to base an IDLH for phenylhydrazine. Therefore, the revised IDLH for phenylhydrazine is 15 ppm based on acute oral toxicity data in animals [Ekshtat 1965]. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for phenyl hydrazine at concentrations above 0.14 ppm.]
1. Ekshtat BY . Maximum permissible concentrations of hydrazine hydrate and phenylhydrazine in water bodies. Gig Sanit 30(8):191-197 (translated).
2. NIOSH . MV89250. Hydrazine, phenyl-. In: Registry of toxic effects of chemical substances, 1976 ed. Cincinnati, OH: U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 76-191, p. 598.
3. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., pp. 2227-2228.
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