Toxicity of Military Smokes and Obscurants Volume 2 (1999) / Chapter Skim
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5 Graphite Smoke
5 Graphite Smoke
Pages 97-114
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From page 97... ...
The military releases the graphite flakes into the environment from ground-based systems that mechanically disperse bulk powders into the atmosphere (windy and Eaton 1994~. The powder is used directly or compressed into small pellets to improve handling and delivery to the air ejector of smoke generators.
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From page 98... ...
In a recent study of the particle size of graphite from an XM56 generator, the mass median diameters for Types ~ and 2 reprocessed infrared material were 3-5 ,um and 47-106 ,um, respectively (Guelta et al.
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Nonasbestos bodies with a black graphite core, superficially resembling the characteristic iron-containing bodies seen after asbestos exposure, are dispersed in the lungs and, occasionally, are found in the sputum (Mazzucchelli et al.
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Analysis of BAL fluid from the lungs of exposed animals 24 hr after exposure showed increased protein content (not statistically significant) and increased activity of alkaline phosphatase and p-glucuronidase for both graphite materials and increased lactate dehydrogenase activity for natural graphite.
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From page 101... ...
Particle sizes were 1.82 ,um for the graphite and 0.36 to 0.69 ,um for the fog oil. A depression in body weight was found only in animals exposed to the graphite or the graphite and fog-oi} mixture.
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From page 102... ...
In addition, pulmonary and mediastinal lymph nodes and lymphoid tissues showed hyperplasia and graphitecontaining granulomas. Oral Exposures Graphite type 6353 and Microfyne dissolved in corn of!
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Fluorescein stain did not reveal abrasion or other lesions of the cornea. Graphite type 6353 and Microfyne were deposited in quantities of 100 mg into the conjunctival sac in rabbits (Manthei et al.
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From page 104... ...
In vitro, graphite has minimal cytotoxicity and no mutagenic activity. PREVIOUS RECOMMENDED EXPOSURE LIMITS The American Conference of Governmental Industrial Hygienists (ACGTH)
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~ cc ~ o ~ ~ ~ I= A: to At :~ ·-to In to X a' .
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From page 106... ...
Associated with the overload of particle clearance by low-toxicity particles in the rat is the development of pulmonary inflammation, fibrosis, and epithelial hyperplasia; inhalation exposures resulting in lung burdens below l-2 mg/g of lung appear to be without adverse effect (Morrow et al. 1991; Oberdorster 19943.
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From page 107... ...
To address the potential for greater responses due to the high-dose rate in acute inhalation exposures, the subcommittee reduced the dose of 2 mg/g of lung by a factor of 10, and estimated the maximal 15-min, 1-hr, and 6-fur exposure concentrations that would result in a lung dose of <0.2 mg/g of lung. Making reasonable assumptions for minute volume (43 L/min, heavy work activity; Diem and Lentner 1970)
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From page 108... ...
Repeated Exposure Guidance Level (REGL) Because the graphite used by the Army is free of silica and has properties similar to other low-toxicity, poorly soluble particles (e.g., titanium dioxide, talc, and carbon black)
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The recommendations for EEGEs were derived by calculating exposure concentrations that would not yield sufficient deposited graphite to cause lung overload. The calculations were verified against biological data on rats for which the calculated graphite lung doses were such that conditions of lung overload were expected.
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sparse, the subcommittee recommends that an acute inhalation study of graphite in rats be conducted, uising multiple concentrations to describe fully the exposure dose-response relationship. Concentrations expected to yield lung burdens of graphite at or below the concentration expected to result in lung overload could be used.
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From page 111... ...
1992. Thirteen-week Inhalation Toxicity Study with Aerosol Mixtures of Fog Oil and Graphite Particles in F344/N Male Rats.
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Army Medical Research Detachment, Wright-Patterson Air Force Base, Ohio, for Walter Reed Army Institute of Research, Washington, D.C. Manthei, J.H., and D.H.
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From page 113... ...
1988. Comparative Inhalation Screen of Titanium Dioxide and Graphite Dusts.
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