Long-Term Continuous Exposure of Guinea Pigs to Sulfur Dioxide

Abstract

Three groups of guinea pigs were exposed to 0.13, 1.01, and 5.72 ppm for 12 months. Pulmonary function measurements including tidal volume, respiratory rate, minute volume, dynamic compliance, pulmonary flow resistance, and carbon monoxide uptake indicated that no detrimental changes could be attributed to sulfur dioxide. Hematology and clinical chemistry measurements were normal, and body weight, growth, and survival were not adversely affected. Microscopic examination of the lung and trachea revealed that the group exposed to 5.72 ppm had a lower incidence and severity of spontaneous disease normally present in those animals after a period of 52 weeks. Microscopic examination of the liver revealed alterations in the animals exposed to 5.72 ppm which were characterized by an increase in the size of the hepatocytes accompanied by cytoplasmic vacuolation.