Emergency and Continuous Exposure Guidance Levels for Selected Submarine Contaminants Volume 3 (2009) / Chapter Skim
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3 Hydrogen Chloride
3 Hydrogen Chloride
Pages 46-69
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From page 46... ...
The committee considered all that information in its evaluation of the U.S. Navy's 1-h, 24-h, and 90-day exposure guidance levels for hydrogen chloride.
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From page 47... ...
. At high concentrations, hydrogen chloride is an irritant to the mucous membranes, eyes, and skin.
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From page 48... ...
Published reports describe immediate skin, eye, and respiratory tract irritation, particularly in the nose, pharynx, larynx, and tracheobronchial tree. The reports described below do not include exposure concentrations, so they are of little use in setting exposure guidelines; they are provided as secondary, supportive evidence of the outcomes observed in quantitative animal exposure studies.
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From page 49... ...
Hypoxemia recurred during two later viral infections that required hospitalization. A neighborhood exposure occurred when a container truck leaked 200 gal of hydrochloric acid while parked 150 ft from a mobile-home park; hydrogen chloride was later found in nearby ditches and a pond (Kilburn 1996)
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Experimental Studies Human exposure studies performed in laboratories in the late 1800s and first half of the 1900s remain an important source of hydrogen chloride exposure-response information (Table 3-2)
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There was a significant rise in oral ammonia concentrations -- a finding that was counterintuitive in that the authors had expected a slight decrease because of neutralization caused by the inhaled acid gas. The authors concluded that people who had mild asthma had no adverse respiratory effects of exposure to hydrogen chloride at low concentrations.
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From page 52... ...
1969 <5 Unspecified Apparently not harmful, may promote tooth Elkins 1959 decay ≥5 Unspecified Immediately irritating Elkins 1959 > 10 Occupational Highly irritating, but workers developed Elkins 1959 some tolerance 10 Prolonged Maximum tolerable Henderson and Hagard 1943 10-50 A few hours Maximum tolerable Henderson and Hagard 1943; Jacobs 1967 35 Short Throat irritation Henderson and Hagard 1943 50-100 1h Maximum tolerable Henderson and Hagard 1943; Jacobs 1967 1,000-2,000 Short (less than 1 h) Dangerous Henderson and Hagard 1943; Jacobs 1967
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From page 53... ...
Workers were then classified into four exposure groups: 0, 0.1-3.9, 4-12.4, and at least 12.5 ppm-years. There was no association between hydrogen chloride exposure and lung cancer whether analyzed by duration of exposure, cumulative exposure, highest average exposure, or latency.
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From page 54... ...
Guinea pigs exercised on the wheel for 10 min before the start of hydrogen chloride exposure. The authors observed gasping and death in guinea pigs exposed at 586 ppm.
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Exposures to hydrogen chloride at 11,800 ppm and higher for 5 min produced extreme irritation of the mucous membranes, eyes, and respiratory tract (Darmer et al. 1974; Kaplan et al.
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From page 56... ...
A decrease in respiratory rate was observed above 40 ppm, and small superficial ulcerations were observed in respiratory epithelium of the nasal cavity near its junction with squamous epithelium at a concentration as low as 17 ppm. As the concentration of hydrogen chloride increased, the mucosal ulcerations increased in severity and extent, gradually extending up the sides and septum of the nasal cavity.
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From page 57... ...
, to formaldehyde at 15 ppm, to a mixture of hydrogen chloride at 10 ppm and formaldehyde at 15 ppm, and to vapors of hydrogen chloride at 10 ppm and formaldehyde at 15 ppm that were not mixed but were introduced simultaneously and separately into the exposure chamber. End points included daily clinical observations, body weights, gross necropsy findings, and histopathologic findings of the nasal cavity, trachea, lar
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From page 58... ...
There are no in vivo genotoxicity inhalation studies of hydrogen chloride, such as a mouse micronucleus assay. Results of an adenovirus SA7 transformation assay of Syrian hamster embryo cells with hydrochloric acid concentrations of 31-500 µg/mL were negative (Casto and Hatch 1978, cited in Heidelberger et al.
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From page 59... ...
Because hydrogen chloride, like hydrogen fluoride, has high water solubility and reactivity, it should also be highly absorbed in the upper respiratory tract of rats. Inhalation studies of hydrogen chloride in laboratory animals have shown tissue injury in the most anterior regions of the nasal cavity with much less or even negligible injury in the posterior areas of the nasal cavity or downstream in the trachea and lungs (Buckley et al.
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produced alterations in respiratory rate or mild irritation, which returned to normal after exposure. However, exercising guinea pigs exposed at 140 ppm or higher exhibited respiratory distress and incapacitation (Malek and Alarie 1989)
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TABLE 3-3 Selected Inhalation Exposure Levels for Hydrogen Chloride from the National Research Council and Other Agenciesa Organization Type of Level Exposure Level (ppm) Reference Occupational ACGIH TLV-ceiling 2 ACGIH 2003 NIOSH REL-ceiling 5 NIOSH 2005 OSHA PEL-ceiling 5 29 CFR 1910.1000 Spacecraft NASA SMAC Lam and Wong 2000 1-h 5 24-h 2.5 30-day 1 180-day 1 Submarine NRC EEGL NRC 1987 1-h 20 24-h 20 CEGL NRC 1987 90-day 0.5 SEAL 1 (10-day)
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From page 62... ...
. Abbreviations: ACGIH, American Conference of Governmental Industrial Hygienists; AEGL, acute exposure guideline level; CEGL, continuous exposure guidance level; EEGL, emergency exposure guidance 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 Safety and Health Administration; PEL, permissible exposure limit; REL, recommended exposure limit; SEAL, submarine escape action level; SMAC, spacecraft maximum allowable concentration; TLV, Threshold Limit Value.
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From page 63... ...
(ppm) EEGL 1-h 5 9 24-h 2 3 CEGL 90-day 1 1 Abbreviations: CEGL, continuous exposure guidance level; EEGL, emergency exposure guidance level.
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From page 64... ...
Thus, the same value was derived with the two approaches, and 3 ppm is recommended as a 24-h EEGL. 90-Day CEGL Biologic end points that were considered the most relevant for derivation of the 90-day CEGL were histopathologic changes in tissues of the respiratory tract after repeated hydrogen chloride exposure.
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From page 65... ...
Little is known about the acid-base buffering capacity of mucous membranes and tissues of the respiratory tract. Because hydrogen chloride dissociates rapidly to hydronium ions on contact with tissue surfaces, studies designed to quantitate the acid-buffering capacity of mucosal surfaces and tissues of the nasal cavity may be of value for studying dosimetry and threshold effects of hydrogen chloride.
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From page 66... ...
Presentation at the First Meeting on Emergency and Continuous Ex posure Guidance Levels for Selected Submarine Contaminants, June 17, 2008, Washington, DC. Hartzell, G.E., H.W.
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From page 67... ...
1977. A semi-quantitative method for assessing anatomic damage sustained by the upper respiratory tract of the labo ratory mouse, Mus musculis.
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From page 68... ...
Pp. 17-30 in Emergency and Continuous Exposure Guidance Levels for Selected Airborne Contaminants, Vol.
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From page 69... ...
1984. 90-Day Inhalation Toxicity Study of Hydrogen Chloride Gas in B6C3F1 Mice, Sprague-Dawley Rats, and Fischer-344 Rats, Revised.
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