Acute Exposure Guideline Levels for Selected Airborne Chemicals Volume 14 (2013) / Chapter Skim
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5 Nitric Acid Acute Exposure Guideline Levels
5 Nitric Acid Acute Exposure Guideline Levels
Pages 139-175
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From page 139... ...
Both the document and the AEGL values were then reviewed by the National Research Council (NRC) Committee on Acute Exposure Guideline Levels.
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From page 140... ...
The point of departure for AEGL-1 values was selected on the basis of a study in which five healthy volunteers were exposed to nitric acid at 1.6 ppm for 10 min and had no changes in pulmonary function (vital capacity, respiratory resistance, and forced expiratory volume [FEV1]
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From page 141... ...
. White fuming nitric acid contains 0.5% dissolved nitrogen dixoide while red fuming nitric acid contains 14% dissolved nitrogen dioxide (ACGIH 1991)
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should be consulted for relevant AEGL values for nitrogen dioxide, nitric oxide, and nitrogen tetroxide. Production of nitric acid atmospheres for inhalation exposure experiments potentially results in a variety of physical states (gas, fume, and vapor)
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Sawdust used to absorb the spill rapidly oxidized and burst into flame. Therefore, firemen were exposed to a mixture of nitric acid fumes and reaction products (e.g., nitrogen monoxide)
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. Nitric acid fumes may cause immediate irritation of the respiratory tract, pain, and dyspnea, which are followed by a period of recovery that may last several weeks.
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. Wheeze prevalence was positively correlated with concentrations of both acid and nitrogen dioxide in boys, whereas regression analysis showed that acid vapor was significantly associated with lower FVC, FEV1, peak expiratory flow rate, and maximal midexpiratory flow in girls.
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From page 146... ...
Concentrations of total oxidation products, expressed as nitrous acid concentration, were determined analytically by either oxidation of hydrogen peroxide or by reduction using potassium iodide. Although the generated atmospheres were likely a mixture of nitrogen oxides, exposure concentrations were expressed as total nitric acid content and are reported in ppm as was done by NIOSH (1976b)
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Nitric acid fumes may cause immediate irritation of the respiratory tract, pain, and dyspnea, followed by a period of recovery that may last several weeks. Relapse may occur, with death caused by bronchopneumonia or pulmonary fibrosis.
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3.1.2. Rats Groups of five male and five female Crl:CD®BR rats were exposed noseonly for to nitric acid aerosol at 260-3,100 ppm for 1 h, followed by a 14-day observation period (DuPont 1987)
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From page 149... ...
Outcomes related to exposure to RFNA and nitrogen dioxide are reported here to provide a complete description of the study; however, the chemicals are not directly relevant to nitric acid fumes. Although graphs of the dose-response curves were presented in the paper, the authors did not include the data from which those curves were plotted.
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From page 150... ...
Bronchiolitis obliterans was produced in dogs after instillation of nitric acid at 1% into the airways. Two instillations of three 5-mL aliquots were given approximately 2 weeks apart and pulmonary function tests performed 2 weeks later.
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3.2.4. Sheep Effects of nitric acid vapor on carbachol reactivity in normal and allergic sheep were investigated (Abraham et al.
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Pulmonary flow resistance from carbachol challenge before and after exposure to nitric acid increased by 68 and 78%, respectively, in normal sheep and 82 and 120% (p ≤ 0.05) , respectively, in allergic sheep (Abraham et al.
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4.3. Structure-Activity Relationships Inhalation exposures to nitric acid fumes involve exposure to nitric acid as well as nitrogen oxides such a nitrogen dioxide (NO2)
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It is apparent from the above discussion that the toxic action of nitric acid cannot be considered without taking into account the effects of nitrogen dioxide. However, nitric acid fumes will contain nitrogen dioxide upon contact with water, such that reports of experimental or accidental exposures to nitric acid fumes will account for the toxicity contributed by nitrogen dioxide.
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was reported for changes in pulmonary function (vital capacity, respiratory resistance, and FEV1) in five healthy volunteers exposed at rest to nitric acid vapor for 10 min (Sackner and Ford 1981)
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Groups of five male and five female Crl:CD®BR rats were exposed nose-only to nitric acid aerosol at 260-3,100 ppm for 1 h, followed by a 14-day observation period. Clinical signs included clear nasal discharge at "some" concentrations, body weight loss for 1-2 days at 260 and 470 ppm, partially closed eyes at concentrations of 1,300 ppm and higher, lung noise and gasping at 1,600 ppm and higher, and extended weight loss for up to 12 days post-exposure at 1,500 ppm and greater for males and 1,600 ppm and greater for females.
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From page 157... ...
Effects observed at 470 ppm were transient body weight loss 1-2 days post-exposure. At the next higher concentration, rats exhibited partially closed eyes (a possible sign of severe ocular irritation)
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From page 158... ...
Groups of five male and five female Crl:CD®BR rats were exposed nose-only to nitric acid aerosol at 260-3,100 ppm for 1 h, followed by a 14-day observation period. Clinical signs included clear nasal discharge at some concentrations, body weight loss for 1-2 days at 260 and 470 ppm, partially closed eyes at 1,300 ppm and higher, lung noise and gasping at 1,600 ppm and higher, and extended weight loss for up to 12 days postexposure at 1,500 ppm and higher for males and 1,600 ppm and higher for females.
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Some of the standards and guidelines have been developed on the basis of nitrogen dioxide or comparisons with other acids in the workplace. An occupational time weighted average (TWA)
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j 2ppm OELV-STV (Sweden) j 5ppm a ERPG (emergency response planning guidelines, American Industrial Hygiene Association)
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f TLV-STEL (threshold limit value – short-term exposure limit, American Conference of Governmental Industrial Hygienists)
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Emergency Response Planning Guidelines, American Industrial Hygiene Association, Fairfax, VA. AIHA (American Industrial Hygiene Association)
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1970. Pulmonary changes in animals ex posed to nitrogen dioxide, effects of acute exposures.
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2001. Standing Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Chemicals.
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P 44 in Occupational Exposure Limit Val ue and Measures against Air Contaminants.
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1981. Effects of breathing nitrate aerosols in high concentrations for 10 minutes on pulmonary function of normal and asthmatic adults, and preliminary results in normals exposed to nitric acid fumes.
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26 pp. Toxicity end points: Exposure to nitric acid at 470 ppm for 1 h resulted in transient body weight loss 1-2 days post-exposure and was a no-effect level for eye closure and impairment of escape.
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3 × 1 h = 776,151.559 ppm-h (919 ppm ÷ 10) 1 × 1 h = 91.9 ppm-h Uncertainty factors: 3 for interspecies differences 3 for intraspecies variability Total uncertainty factor of 10 Modifying factor: None Calculations: 10-min AEGL-3: C = (776,151.559 ppm-h ÷ 0.167 h)
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1981. Effects of breathing nitrate aerosols in high concentrations for 10 minutes on pulmonary function of normal and asthmatic adults, and preliminary results in normals exposed to nitric acid fumes.
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From page 170... ...
Modifying factor: 2, because clinical observations were not well described, and AEGL-2 and AEGL-3 values overlap suggesting a very steep concentration-response relationship. Animal-to-human dosimetric adjustment: Not applicable Time scaling: Cn × t = k; n = 3 for extrapolating to the 10- and 30-min durations, and n = 1 for extrapolating to the 4- and 8-h duration Comments: Nitrogen dioxide content monitored during exposures; none measured.
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From page 171... ...
Intraspecies: 3, because the mechanism of action of a corrosive acid in the eye or lung is not expected to differ greatly among individuals. Modifying factor: None Animal-to-human dosimetric adjustment: Not applicable Time scaling: Cn × t = k; n = 3 for extrapolating to the 10- and 30-min durations, and n = 1 for extrapolating to the 4- and 8-h durations Comments: Nitrogen dioxide content monitored during exposures; none measured.
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From page 172... ...
of Source Species Sex Exposures ppm Minutes Category Comments NAC/AEGL-1 0.16 10 AEGL NAC/AEGL-1 0.16 30 AEGL NAC/AEGL-1 0.16 60 AEGL NAC/AEGL-1 0.16 240 AEGL NAC/AEGL-1 0.16 480 AEGL NAC/AEGL-2 43 10 AEGL NAC/AEGL-2 30 30 AEGL NAC/AEGL-2 24 60 AEGL NAC/AEGL-2 6 240 AEGL (Continued)
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From page 173... ...
; partially closed eyes Rat Both 1 1,500 60 SL Mortality (1/10) ; weight loss Rat Both 1 1,600 60 SL Mortality (2/10)
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174 Acute Exposure Guideline Levels APPENDIX D DERIVATION OF LC01 VALUE FOR NITRIC ACID Filename: ten Berge Spreadsheet Data for Log Probit Model Date: 01 March 2012 Time: 16:01:18 Sequence No. Concentration (ppm)
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From page 175... ...
Nitric Acid 175 Estimation of ppm at response of 1% Point estimate ppm = 9.192E+02 for response of 1% Lower limit (95% CL) ppm = 3.509E+02 for response of 1% Upper limit (95% CL)
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