Comparative study of various methods used for determining health effects of inhaled sulfates

Various health effect parameters were compared to determine which tests were the most sensitive indicators of toxic effects of exposure to metallic sulfate aerosols. Inhalation studies were conducted involving either single 3-hr exposure to various concentrations of cupric sulfate (0.43-2.64 mg/m3 SO4), aluminum sulfate (1.65-2.75 mg/m3 SO4), and aluminum ammonium sulfate (1.47-3.81 mg/m3 SO4) or multiple (five and ten) daily 3-hr exposures to cupric sulfate (0.1 mg/m3 SO4). The test parameters studied in male and female CD1 mice were changes in mortality after respiratory infection with Group C Streptococcus zooepidemicus; pulmonary bactericidal activity; pulmonary cell number, type, viability, and ATP content; and pulmonary morphology by scanning electron microscopy. Tracheal ciliary beating frequency and morphology were also studied in both CD1 mice and Syrian golden hamsters. Differences in bacteria-induced mortality rate appeared to be the most sensitive and consistent indicators of pollutant damage. The other parameters produced evidence of damage but generally only at the higher pollutant concentrations. Cupric sulfate was the most toxic of the three sulfates, but the differences between the toxicity of the aluminum sulfate and aluminum ammonium sulfate were less clear.