Physiological Effects

1 ACUTE TOXICITY

INHALATION AT CERTAIN CONCENTRATIONS CAN LEAD TO INJURY OR DEATH (refer to Table B-l). Exposure to concentrations below 20 ppm can cause eye ir­ritation, throat irritation, respiratory tract irritation, chest constriction, and some nausea. Exposure to concentrations above 20 ppm can result in marked coughing, sneezing, eye irritation, and chest constriction. Exposure to 50 ppm causes irritation to the nose and throat, running nose, coughing, re­flex broncho-constriction with possible increase in bronchial mucous secretion, and increased pulmonary resistance to air

"•""TLV" is a trademarked term of the American Conference of Govern­mental Industrial Hygienists (ACGIH). Refer to Threshold Limit Values and Biological Exposure Indices and companion documents available from ACGIH, 1330 Kemper Meadow Drive, Cincinnati, OH 45240 (check latest edition).

flow (breathing congestion) occurs promptly. This atmo­sphere (50 ppm or more) will not be tolerated by most per­sons for more than 15 minutes. Some reported acute reactions of exposure to high concentrations include, but are not limited to, inflammation of the eyes, nausea, vomiting, abdominal pain, and sore throat. These symptoms are some­times followed by bronchitis, pneumonia, and /or complaints of weakness for a period of weeks.

B.3.2 CHRONIC TOXICITY

It has been reported that prolonged exposures to sulfur dioxide may lead to increased risk of chronic nasopharyngi-tis, alteration in sense of smell and taste, shortness of breath on exertion, and a higher frequency of respiratory tract infec­tions compared to unexposed persons. It has also been pos­tulated that sulfur dioxide in the work environment "possibly enhances" the suspected carcinogenic (cancer) effect of ar­senic or other cancer agents'"'. No definite evidence is avail­able regarding co-carcinogenesis or promotion of cancer by sulfur dioxide exposure. A few persons apparently have or develop a hypersusceptibility to sulfur dioxide. Decrements in pulmonary function tests have been noted after both acute and chronic exposures.

B.3.3 EXPOSURE RISKS

It is not yet clear what concentrations of low level expo­sure or lengths of exposure increase the risks, nor by how much the risks are increased. Sulfur dioxide exposures should be minimized. Smoking by persons exposed to sulfur dioxide should be strongly discouraged.