Long-Term Continuous Exposure to Sulfur Dioxide and Fly Ash Mixtures

Abstract

Three groups of cynomolgus monkeys and three groups of guinea pigs were exposed to mixtures of sulfur dioxide (SO₂) and fly ash while one group of each species was used as a control group. The exposure concentrations for SO₂ were 0.1, 1.0, and 5 ppm, and 0.5 mg/cu m of fly ash was combined with each of the SO₂ concentrations. The duration of exposure was 52 weeks in guinea pigs and 78 weeks in monkeys. Pulmonary function tests and serum biochemical and hematological analyses were conducted prior to and during the exposure period. At termination of exposure, microscopic examination of the lung was performed. Analysis of the data revealed that no adverse effects in guinea pigs or monkeys could he attributed to exposure to the mixtures of SO₂ and fly ash.