Hygienic Studies on Exposure Experiments of Laboratory Animals to Air Pollutants

Report I Histopathological Changes of Rats Fed in Normal Diet and Promotion of Fur Loss on Vitamin B₁-Deficient Rats under the Conditions of Exposure to Low Level Sulfur Dioxide

Abstract

Rats were exposed to 0.1 and 0.5 ppm SO₂ continously for 4 weeks. The histopathological examinations revealed the inflammatory changes such as submucosal histiocytic infiltration, submucosal lymphoid hyperplasia and thickning of alveolar wall on respiratory tract in both group. These findings were not evident in the control group. The histopathological findings of rats exposed to 0.5 ppm SO₂ showed higher severity than those exposed to 0.1 ppm SO₂. The histochemical findings of activities of acid phosphatase, alkaline phosphatase, NADH diaphorase in the tissue of trachea and lung revealedthe similar inflammatory changes as noted in histopathological examinations.
The loss of fur in vitamin B₁-deficient rats exposed to 0.5 ppm SO₂ was observed earlier than in those exposed to 0.1 ppm SO₂ or in those non-exposed rats. General emaciation of vitamin B₁-deficient rats seemed to be promoted by exposure to 0.5 ppm SO₂.