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6 Hydrazine
Pages 139-166

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From page 139...
... , 24-h, and 90-day exposure guidance levels for hydrazine. The subcommittee's recommendations for hydrazine exposure levels are provided at the conclusion of this chapter along with a discussion of the adequacy of the data for defining those levels and the research needed to fill the remaining data gaps.
From page 140...
... 140 EEGLs and CEGLs for Selected Submarine Contaminants TABLE 6-1 Physical and Chemical Properties of Hydrazinea Synonyms and trade Diamine, diamide, anhydrous hydrazine, names hydrazine base, nitrogen hydride CAS registry number 302-01-2 Molecular formula NH2NH2 Molecular weight 32.05 Boiling point 113.5°C Melting point 2.0°C Flash point 52°C (open cup) Explosive limits 4.7% to 100% Specific gravity 1.0036 at 25°C/4°C Vapor pressure 14.4 mmHg at 25°C Solubility Soluble in water and methyl, ethyl, propyl, and isobutyl alcohols 1 ppm = 1.3 mg/m3; 1 mg/m3 = 0.76 ppm Conversion factors a Data on explosive limits and vapor pressure are from ACGIH (2001)
From page 141...
... (1999) , and the American Conference of Governmental Industrial Hygienists (ACGIH)
From page 142...
... . However, the potential cancer risk from inhalation exposures to hydrazine cannot be determined from the available human studies.
From page 143...
... . Clinical signs and symptoms included vomiting, weakness, dyspnea, confusion, lethargy, ataxia, restlessness, and loss of consciousness.
From page 144...
... to 2.10 (95% CI = 1.36-3.25) depending on exposure duration and lag time for hydrazine exposure.
From page 145...
... and the dermal LD50 values reported in rabbits and guinea pigs (93190 mg/kg) (Rothberg and Cope 1956)
From page 146...
... The protocol used two designs: (1) continuous exposures at 0.2 or 1 ppm for 24 h per day, 7 days per week (33.6 or 168 ppm-h per week)
From page 147...
... Hepatic fatty infiltration was evident in mice at all exposure concentrations, which is consistent with observations of dogs that inhaled hydrazine at 3-6 ppm for 19 days reported in Weatherby and Yard (1955)
From page 148...
... The body weights of female rats were significantly reduced during the exposure period. Proliferative lesions (focal squamous epithelial hyperplasia and squamous cell carcinoma)
From page 149...
... The first appearance of nasal tumors in male and female rats occurred at 20 and 23 months, respectively, following initiation of exposure. Groups of 400 female C57BL/6 mice were exposed to hydrazine at 0.05, 0.25, or 1.0 ppm and maintained for 15 months post-exposure.
From page 150...
... Reproductive Toxicity in Males No relevant studies were identified. Immunotoxicity Allergic contact dermatitis related to hydrazine exposure is common among people who do not take precautions to prevent skin contact (ATSDR 1997; ACGIH 2001)
From page 151...
... 151 Hydrazine at oxidant concentrations that exceed the capacity of antioxidant systems are likely to result in oxidant DNA damage. Highly reactive chemicals also might interact with the DNA in bacterial systems differently than they do with DNA in mammalian systems.
From page 152...
... The numbers of mice with alveolargenic carcinomas increased with exposure concentration (one of eight at 0 ppm; two of six at 1 ppm, intermittent; three of eight at 0.2 ppm, continuous; five of six at 5 ppm, intermittent; and five of nine at 1 ppm, continuous)
From page 153...
... 153 Hydrazine 1993)
From page 154...
... 154 EEGLs and CEGLs for Selected Submarine Contaminants TOXICOKINETIC AND MECHANISTIC CONSIDERATIONS Hydrazine kinetics and metabolism have not been fully characterized. Hydrazine is eliminated in rat urine as acetylhydrazine, diacetylhydrazine, and 1,4,5,6-tetrahydro-6-oxo-3-pyridazine carboxylic acid (Sanins et al.
From page 155...
... There are no genotoxicity data available for humans via any exposure route, and epidemiologic data are considered inadequate for determining the carcinogenic potential of hydrazine in humans. INHALATION EXPOSURE LEVELS FROM THE NRC AND OTHER ORGANIZATIONS A number of organizations have established or proposed exposure limits or guidelines for inhaled hydrazine.
From page 156...
... . A similar inhalation study involving continuous exposure at 1 ppm for 24 h per day, 7 days per week for 6 months or intermittent exposure at 5 ppm for 6 h per day, 5 days per weeks for 6 months in four female rhesus monkeys resulted in minimal ocular irritation during the first few weeks of the study (Haun and Kinkead 1973)
From page 157...
... 0.1 Proposed AEGL-2 (8 h) 1.6 NRC SPEGL NRC 1985 1h 0.12 24 h 0.005 a The comparability of EEGLs and CEGLs with occupational and public health standards or guidance levels is discussed in Chapter 1, section "Comparison to Other Regulatory Standards or Guidance Levels." Abbreviations: ACGIH, American Conference of Governmental Industrial Hygienists; AEGL, acute exposure guideline level; ATSDR, Agency for Toxic Substances and Disease Registry; h, hour; MRL, minimal risk level; NAC, National Advisory Committee; NASA, National Aeronautics and Space Administration; NIOSH, National Institute for Occupational Safety and Health; NRC, National Research Council; OSHA, Occupational Health and Safety Administration; PEL, permissible exposure limit; ppm, parts per million; REL, recommended exposure limit; SMAC, spacecraft maximum allowable concentration; SPEGL, short-term public emergency guidance level; TLV, Threshold Limit Value; TWA, time-weighted average.
From page 158...
... U.S. Navy Values NRC Recommended Exposure Level Current Proposed Values EEGL 1h -- 4 1 24 h 0.3 1 -- CEGL 90 days 0.01 0.03 -- Abbreviations: CEGL, continuous exposure guidance levels; EEGL, emergency exposure guidance level; h, hour; NRC, National Research Council; ppm, parts per million.
From page 159...
... Application of an interspecies uncertainty factor of 3 to the monkey 6-month continuous exposure no-observed-adverse-effect level (NOAEL) or possibly minimal LOAEL of 0.2 ppm was considered appropriate.
From page 160...
... Chronic hydrazine inhalation studies in rats and mice yield concentration-related nasal and lung tumors. Hydrazine is clearly genotoxic in rats, mice, hamsters, and guinea pigs, inducing dose-dependent increases in hepatic O6-methylguanine and 7-methylguanine (Bosan and Shank 1983; Lambert and Shank 1988)
From page 161...
... TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices.
From page 162...
... 2004. Acute Exposure Guideline Levels (AEGLs)
From page 163...
... 1964. Tolerance Criteria for Continuous Inhalation Exposure to Toxic Materials, III.
From page 164...
... Pp. 5-21 in Emergency and Continuous Exposure Guidance Levels for Selected Airborne Contaminants, Vol.
From page 165...
... , Short-Term Public Emergency Guidance Level (SPEGL) , and Continuous Exposure Guidance Level (CEGL)
From page 166...
... 1985. Long-term inhalation toxicity of hydrazine.


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