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Respiratory symptoms are frequently reported in personnel deployed to the Middle East. This project characterized the respiratory toxicity of inhaled Iraqi sand (IS). Adult rats underwent a 6-wk inhalation to air or mainstream cigarette smoke (MSCS) (3h/d, 5d/wk) that included exposure to IS or crystalline silica (1 mg/m3, 19h/d, 7d/wk) or air during the last w weeks. Assessments included motor activity, whole-body plethysmography, cytological and biochemical analysis of bronchoalveolar lavage fluid, lung metal burden, nasal and lung pathology and changes in lung protein and gene expression. A number of metals including nickel, manganese, and vanadium concentrations wee seen in IS-exposed rats, suggesting that several metals present in IS are bioavailable. Rats exposed to IS only developed mild inflammation in the anterior nose and lung. Silica inhalation was associated with some pulmonary responses that were not seen in IS-exposed rats, such as mild laryngeal and tracheal inflammation, mild tracheal epithelial hyperplasia, and elevated lung silica concentrations. MSCS inhalation with or without co-exposure to MSCS and silica has more widespread airway lesions when compared with rats exposed to MSCS only. Silica-exposed rats had more robust pulmonary gene expression and proteomic responses than that seen in IS-exposed rat. Our studies show that the respiratory toxicity of IS is qualitatively similar to or less than that seen following short-term silica exposure.

1,4-dioxane has been used as a stability additive in a number of industrial solvents and has found its way into the environment, especially in groundwater. At current and former military installations where solvents were used, there has been growing concern for assessing the health risk involving human exposure to dioxane. Consequently, we conducted an acute inhalation study, in which we exposed male and female Fischer 344 rats for 6 hours to 0, 100, 300, 800, 2200 or 6000 ppm dioxane and assessed them at 2 days post-exposure or 2 weeks following a recovery period. We also conducted a two-week inhalation study, in which we exposed male and female rats 6 hours/day, 5 days/week to 0, 100, 1600 or 3200 ppm dioxane and assessed them at 1 day post-exposure or following the 2-week recovery period. In the acute study, two rats in the highest exposure groups had vacuolar changes in their nasal cavities two days post-exposure but they fully recovered after two weeks. In the two-week study, animals responded with numerous degenerative changes (lesions in nasal cavity, liver and kidney; hepatic single-cell necrosis). Male rats in the mid- and high concentration groups did not recover fully from hepatic single cell necrosis two weeks after exposure. The lowest observed adverse effect level (LOAEL) for 1,4-dioxane in the 2-week study is 100 ppm., PDF updated 24 Jun 2013.

FT jet fuel is a synthetic organic mixture produced using the Fischer-Tropsch (FT) process that is being developed to replace or augment petroleum-derived JP-8 jet fuel for military use by the U.S. armed forces. The FT toxicity testing program results are reviewed. The final study, sensory irritation potential in male Swiss-Webster mice, is evaluated. Groups of four mice were exposed for 30 minutes to FT jet fuel vapor/aerosol atmospheres. Group mean exposure concentrations were 2225, 6844 and 9425 mg/m3. FT jet fuel evoked breathing patterns characteristic of upper airway sensory irritation. The RD50 (50 percent respiratory rate depression) value was calculated to be 10939 mg/m3. JP-8 has an RD50 of 2,876 mg/m3. FT jet fuel is less irritating than JP-8. A health hazard assessment was conducted for FT jet fuel utilizing all of the following studies: dermal irritation test (FT vs. JP-8 vs. 50/50 blend), in vitro genotoxicity tests, acute inhalation study, short-term inhalation rangefinder study, in vivo genotoxicity test in tandem with the short-term study, 90-day inhalation toxicity study and sensory irritation assay. The sensory irritation RD50 was found to be the most sensitive endpoint. Based on the proposed use of FT jet fuel as a 50/50 blend with JP-8, an occupational exposure limit (OEL) for FT jet fuel is recommended at 200 mg/m3, in concurrence with the current JP-8 OEL of 200 mg/m3., Prepared in collaboration with USAF School of Aerosapace Medicine, Department of Occupational & Environmental Health, Risk Analysis Branch, Wright-Patterson AFB, OH; Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright-Patterson AFB, OH; The Hamner Institutes for Health Sciences, Research Triangle Park, NC, and US Navy Drug Screening Laboratory, San Diego, CA.

FT or S-8 jet fuel is a synthetic organic mixture produced using the Fischer-Tropsch (FT) process that converts natural gas to liquid hydrocarbons. This study was designed to assess the potential inhalation toxicity of FT jet fuel aerosol and vapor via whole-body inhalation exposure to male and female Fischer-344 rats for 6 hours per day, 5 days per week over approximately 90 days, at concentrations of 0, 200, 700, and 2000 mg/cu m. In the motor activity test, males exposed to the highest concentration of FT jet fuel showed a reduction in total activity; the females in the same group displayed a reduction in the initial exploratory activity. Neurobehavioral function was assessed using the Functional Observation Battery (FOB). A reduction in rearing behavior was observed in females exposed at the highest concentration. Olfactory epithelial degeneration and respiratory epithelial hyperplasia was observed in the nasal airways of the high concentration male and female rats. In the lung, minimal to mild multifocal areas of inflammatory cell infiltration were observed in the high concentration groups in male and female rats. Animals exposed to the high concentration of jet fuel showed somewhat lower body weights. Differences in the average organ weights were seen between the high exposure concentration and controls in the liver, thymus, epididymides, spleen, and heart of male rats, and lungs, kidneys, and brain of females. No significant differences were observed for the andrology endpoints or the vaginal cytology results. Toxicity results were comparable to current jet fuel, JP-8., The original document contains color images.

FT (or S-8) jet fuel is a synthetic organic mixture produced using the Fischer-Tropsch (FT) process that transforms natural gas to liquid hydrocarbons. Studies are being conducted to thoroughly evaluate the toxicity of FT jet fuel. First, an acute inhalation toxicity limit test was conducted; FT jet fuel with additives was administered via inhalation exposure to rats once for 4 hours at the maximum specified concentration (2000 mg/m3). No lethality or adverse clinical signs were demonstrated. In the second study, FT jet fuel, with JP-8 additive package, was administered as an aerosol and vapor mixture via repeated inhalation exposure to rats for 6 hours per day, 5 days per week over 2 weeks at concentrations of 0, 500, 1000 and 2000 mg/m3. A slight but significant effect on bodyweight was observed in males exposed to the high (2000 mg/m3) concentration. In the nasal tissues at the intermediate (1000 mg/m3) and high (2000 mg/m3) concentrations, minimal to mild olfactory epithelial degeneration was observed, increasing with the higher concentration, and with deeper penetration into the nose. In the lung, foci of inflammatory cell infiltration were observed in all high and some intermediate concentration exposure group animals. FT jet fuel is similar to or less toxic than JP-8 in equivalent tests. In addition, micronucleus induction was tested; FT jet fuel does not induce micronuclei, indicating that the fuel is not genotoxic. A hydrocarbon fingerprint analysis of the aerosol and vapor phase of the delivered test fuel was performed.

Two assays were performed in order to investigate the potential of Fischer Tropsch (F-T) jet fuel for its ability to induce genotoxicity. First, to determine its ability to induce gene mutations, the plate incorporation test was performed with the Salmonella typhimurium strains TA 98, TA 100, TA 102, TA 1535 and TA 1537. No toxic effects of the test item were noted in any of the five tester strains used up to the highest dose group evaluated (with and without metabolic activation). F-T jet fuel did not cause gene mutations by base pair changes or frameshifts in the genome of the tester strains used. Therefore, F -T jet fuel is considered to be non-mutagenic in this bacterial reverse mutation assay. Second, to investigate a possible potential of F -T jet fuel for its ability to induce structural chromosome aberrations in human lymphocytes in vitro, a chromosome aberration assay was carried out. During the described in vitro chromosomal aberration test and under the experimental conditions reported, the test item F-T jet fuel did not induce structural chromosomal aberrations in human lymphocyte cells. Therefore, F-T jet fuel is considered to be non-clastogenic in this chromosome aberration test., Prepared in collaboration with BSL Bioservice, Planegg, Germany.