Toxicity of Long-Term Exposure to Oxides of Sulfur

Abstract

Hematological and pulmonary function data were collected on 32 female beagles exposed to 13.4 mg/cu m of sulfur dioxide and 0.9 mg/cu m of sulfuric acid alone and in combination. Exposures averaged 21 hours daily for 620 days. Sixteen of these dogs had prior exposure to 48.9 mg/cu m of nitrogen dioxide for 191 days. Exposure to NO₂ altered several hematological indexes and produced hyperinflated Sungs. Hematological indexes were not affected by exposure to oxides of sulfur. Exposure to SO₂ significantly increased mean nitrogen washouts, P < .01, in dogs without prior exposure to NO₂. Exposure to 0.9 mg/cu m of H₂SO₄ significantly reduced carbon monoxide diffusion capacity, residual volume, total Sung volume, and heart weights, and increased total expiratory resistance, P < .05. Histopathologic lung changes were nonspecific for oxides of sulfur exposures; renal changes noted in non-NO₂ exposed animals were equivocal.