Studies on the Inhalation Toxicity of Dyes Present in Colored Smoke Munitions. Phase IV. 90-Day Inhalation Exposures of Rats to Dye Aerosols

Abstract : The U.S. Army has an interest in the potential inhalation toxicity of yellow dye (SY) and a yellow/green dye mixture (SY/SG) used in colored smoke munitions. Rats were exposed by inhalation to aerosols of SY or SY/SG generated in a respirable particle size range (2.1-4.2 micrometers mass median aerodynamic diameter) for 6 hr/day, 5 days/week for a period of 90 days. The objective was to determine an exposure concentration that produced no observable adverse effects. Nominal exposure concentration that produced no observable adverse effects. Nominal exposure concentrations selected for both dye exposures were 0, 1, 10, and 100 mg/cu.m. Actual concentrations were within 10% of these nominal concentrations. Animals exposed to the highest concentration of SY (100 mg/cu.m) had only a slight decrease in body weight gain of 4 percent compared to control animals and an accumulation of foamy macrophages in lungs. Exposure to the lower concentrations of SY dye elicited no observed response. Animals exposed to the highest level of SY/SG dye (100 mg/cu.m) had pulmonary inflammation (as judged by increased lactate dehydrogenase activity, protein and neutrophil numbers in lung lavage fluid) with histopathological evidence of mild Type II pulmonary epithelial cell hyperplasia and proliferation of foamy alveolar macrophages. Some of the animals exposed to the medium concentration of SY/SG dye mixture (10 mg/cu.m) produced similar, but milder histopathological results. Thus, the no- observable-adverse effects level for inhalation exposure to SY dye was 10 mg/cu. m while that of SY/SG dye was 1 mg/cu.m under the exposure regime used.