Spacecraft Maximum Allowable Concentrations for Selected Airborne Contaminants Volume 4 (2000) / Chapter Skim
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B11 Dichlorodifluoromethane (Freon 12)
B11 Dichlorodifluoromethane (Freon 12)
Pages 227-239
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From page 227... ...
Reactivity: Conversion factors at 25°C, 1 atm: 4332 torr at 20°C Insoluble in water (0.028 g/100 g at 25°C) Soluble in alcohol and ether Most halocarbons react violently with highly reactive materials, such as alkali and alkaline earth metals, sodium, potassium, and barium, in their free metallic form.
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From page 228... ...
inhaled for 7-17 min at 1000 ppm by a man and a woman was recovered quantitatively in the exhaled breath with only trace amounts of radioactivity found in exhaled carbon dioxide (0.08°/O in both subjects) andrecovered as nonvolatile materials in the urine (0.02% and 0.03°/O)
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From page 229... ...
Acute and Short-Term Exposures Cardiac Arrhythmia In two human volunteers, no adverse effects in continuous EKG monitoring were seen during a 2.5-h exposure to CFC-12 at 10,000 ppm (Azar et al.1972~. At 110,000 ppm, however, a "significant degree of cardiac arrhythmia" was reported in a single volunteer within the first ~ 0 min of exposure (Kehoe ~ 943~.
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From page 230... ...
In anesthetized rats, there was no alteration in heart rate and rare minor alterations in the EKG pattern. In rats with experimentally induced pulmonary emphysema, inhalation of CFC- 12 at 400,000 ppm resulted in EKGs displaying ventricular extrasystoles (Watanabe and Aviado 1975~.
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, inducing slight retching movements during a 30-min exposure (NuckolIs 1933~. Longer exposure times at 193,000 ppm and increased concentrations up to 304,000 ppm led to increasingly severe signs of CNS effects, including deeper breathing, tremors, weakness, lethargy, and inability to stand.
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1977~. The sensitizing effect of epinephrine in lowering the concentration of CFC12 required to induce cardiac dysrhythmias has been described in the preceding sections.
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Not set ACGIH 1998 ACGIH l991b ACGIH199lb ACGIH l991b ACGIH l991b TLV, Theshold Limit Value; TWA, time-weighted average; PEL, permissible expo sure limit; STEL, short-term exposure limit; REL, recommended exposure limit. TABLE 11-3 Spacecraft Maximum Allowable Concentrations Concentration, Concentration, Duration ppm mg/m3 Target Toxicity 1 h 540 2600 Tachycardia 24h 95 470 Cardiac sensitization to arrhythmia 7 da 95 470 Cardiac sensitization to arrhythmia 30d 95 470 Cardiac sensitization to arrhythmia 180 d 95 470 Cardiac sensitization to arrhythmia Previous 7-d SMAC = 100 ppm (490 mg/m3)
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as a starting point and dividing the LOAEI~ by 10 to estimate a NOAEL yields 2700 ppm. To set a 1-h AC, that value is then divided by S for potential spaceflight effects on cardiac arrhythmias.
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237 CD o · _ o v D Cd Cal o ·_ Ct C)
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Pp 420-422 in Documentation of the Threshold Limit Values and Biological Exposure Indices, Vol.1,6th Ed. American Conference of Governmental Industrial Hygienists, Cincinnati, OH.
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From page 239... ...
1992. Guidelines for Developing Spacecraft Maximum Allowable Concentrations for Space Station Contaminants.
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