Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 4 (2000) / Chapter Skim
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B5 Methylhydrazine
B5 Methylhydrazine
Pages 119-136
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From page 119... ...
. It is a strong reducing agent; its vapor is extremely reactive and undergoes rapid autoxidation in air (NAS 1974~.
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and `decreased slowly thereafter. As the dose increased, the time required to reach peak blood concentrations increased and the rate of subsequent decline decreased until, with doses of 4-6 mmolA |
From page 121... ...
Acute exposures can produce nose and eye irritation, anemia, biTirubinemia, methemogiobinemia, vomiting, neurological effects, damage to lungs, liver, kidney, and brain, convulsions, and death. Chronic exposures can produce anemia, methemogiobinemia, liver, spleen, and kidney damage, and cancer.
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From page 122... ...
~ 9671. Even in anesthetized dogs, MH liquid applied to the skin caused convulsions at plasma concentrations of at least 10 mg/mE, with the time of onset of convulsions varying generally with the dose applied and the plasma concentration of MH (Smith and Clark 1969~.
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(1969) studied the acute inhalation toxicity of MH in rats, mice, beagles, squirrel monkeys, and rhesus monkeys at a range of MH concentrations from 25 ppm to about 500 ppm.
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The rodents that developed all of the toxic signs except convulsions survived, whereas those that convulsed died during or following exposure. The mice that succumbed to MH usually died immediately after a single convulsive seizure.
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In another study at Wright-Patterson Air Force Base, dogs, hamsters, rats, and mice were exposed 6 in/d, 5 d/w for ~ y to MH vapors at 0, 0.02, 0.2, 2.0, and 5.0 ppm (Kroe 19711. Non-neoplastic lesions observed at statistically significant frequencies included: at 0.02 ppm, nasal inflammation and plasmacytosis of the mandibular lymph node in mice; at 0.2 ppm, liver cysts in mice and hamsters, kidney cysts and angiectasis in mice, and rhinitis and submucosal cysts of the nares in hamsters; at 2 ppm, nasal polyps, kidney interstitial fibrosis and lung atelectasis in hamsters, and, in mice, bile duct hyperplasia, hepatocyte pleomorphism, gall bladder crystals, and kidney hydronephrosis.
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From page 126... ...
Those effects follow the administration of toxic doses that are irritating to the sensitive nasal epithelium of the rodent over most of its lifetime. The main target organs are the liver, lungs, and the nasal epithelium (following inhalation)
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From page 127... ...
METHY[HYD~ZINE 127 dependent enzymes such as DOPA decarboxylase and glutamic acid decarboxylase (Furst et al.
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129 ~ at _ ~ Cd .
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The initial overt signs of acute MH toxicity in mice, rats, dogs, and monkeys include irritation of nose and eyes and methemogiobiniemia (seen as hemolytic anemia and Heinz bodies in humans, monkeys and dogs and black or mottled liver in dogs)
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From page 131... ...
Because there are no dose-response data for nasal injury, a safety factor of 10 was used to estimate the NOAEL. An additional safety factor of 10 is warranted to account for the fact that a single sniff caused the observed effects, whereas the AC must be set to protect during continuous, much longer term potential exposures.
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Because the mode] is conservative, no safety factor was used to convert animal test data to human exposure limits.
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during chronic exposure conditions. The methemogiobinemia reaches an equilibrium level unique to the exposure concentration and is accompanied by Heinz body formation (Darmer and MacEwen 1973~.
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TR-WSTF-140. NASA Johnson Space Center, White Sands Test Facility, Las Cruces, N.M.
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From page 136... ...
1992. Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants.
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