Mary O. Amdur

The effect of various aerosols on the response of guinea pigs to sulfur dioxide.

Various types of particulate aerosols (1 to 21 mg/m/sup 3/) were tested for significant synergistic effect with SO/sub 2/. Pulmonary resistance increase after 1-h exposure was the measure of irritation. The 2.6 ppM SO/sub 2/ increased resistance 20%; 10 mg/m/sup 3/ NaCl, KCl, and NH/sub 4/SCN aerosols with approx. 2 ppM SO/sub 2/ increased resistance approx. 47, 68 and 103%, respectively. Potentiation ratio (aerosol/SO/sub 2/ alone) was 2.4, 3.3, and 5.0, respectively, which corresponds with solubility of SO/sub 2/ in the particular salt. Soluble Fe, Mn, and V aerosols also potentiated SO/sub 2/, but insoluble salts of Fe and Mn had no effect. These catalytic aerosols worked faster than NaCl possibly because they convert SO/sub 2/ to H/sub 2/SO/sub 4/. Fly ash may have had a beneficial effect, but only statistical manipulations made it significant. Resistance returns to normal after SO/sub 2/ exposure but remains elevated after SO/sub 2/:aerosol exposure (studied for 5 h post-exposure at maximum). Both solubility and conversion to H/sub 2/SO/sub 4/ are responsible for effects noted.

Toxicologic appraisal of particulate matter, oxides of sulfur, and sulfuric acid

An examination of the available toxicological literature indicates that sulfur dioxide itself would be properly classified as a mild respiratory irritant, the main portion of which is absorbed in the upper respiratory tract. The reported industrial experience of symptoms of mild chronic respiratory irritation from exposures at or above 5 ppm is compatible with what would have been predicted on the basis of available toxicological data. The basic physiological response to inhalation of pure SO2 appears to be a mild degree of bronchoconstriction reflected in a measurable increase in flow resistance. Although the response is highly variable, most individuals tested have responded to 5 ppm and levels of 5 to 10 ppm have upon occasion produced severe bronchospasm in sensitive individuals. This serves to point up the fact that experience with the industrial Threshold Limit Value (5 ppm) is not applicable as a guide for the general population. Although the majority of individuals tested have shown no detectable ...

Respiratory response of guinea pigs to low levels of sulfuric acid

Abstract Sulfuric acid at concentrations of 0.1 to 1 mg/m 3 produces an increase in pulmonary flow resistance and a decrease in pulmonary compliance in guinea pigs exposed for 1 hour. These changes are not rapidly reversible following termination of exposure. Sulfuric acid of 0.3 μm (MMD) was more irritant than a larger size of 1 μm.

Comparative irritant potency of sulfate salts.

Abstract Guinea pigs were exposed for a period of 1 hour to aerosols of sulfate salts. With the exception of sodium sulfate, all the sulfates caused a slight increase in pulmonary flow resistance and a slight decrease in pulmonary compliance. The order of irritant potency was ammonium sulfate > ammonium bisulfate > cupric sulfate. All the sulfate salts were less irritant than sulfuric acid. The particle size range was limited (0.1–0.8 μm, mass median diameter), but, in general, the degree of response increased with decreased size. Of the four sulfates tested, only copper sulfate potentiated the response to sulfur dioxide. The possible practical implications of these findings are discussed.

Aerosols formed by oxidation of sulfur dioxide. Review of their toxicology.

Literature relating to the toxicology of sulfuric acid and particulate sulfates is reviewed. These materials, which have a greater irritant potency than sulfur dioxide, may be formed in the atmosphere by oxidation of sulfur dioxide. Thus, air quality standards for sulfur dioxide must take into account the toxicology of these oxidation products. The particle size of the particulate oxidation products of sulfur dioxide is of extreme importance. Data on concentration alone are insufficient to predict irritant potency. The most important size range is at the submicron level. Data on animal experiments, including the criteria of mortality, pathological findings in the lung, and studies utilizing altered pulmonary function are discussed. Additional data are needed on exposure of human subjects. Experiments must be performed so that both physiological methodology and aerosol technology are properly controlled.

Respiratory absorption data and SO2 dose-response curves.

The authors studies can be grouped to give SO/sub 2/ dose-response curves from 0.1 to 800 ppM (0.4 to 100 ppM with tracheal cannula) with response as pulmonary flow resistance. The author uses Strandbergs data on rabbits to estimate lung penetration in her experiments with guinea pigs, and so straightens curve on log-log scale and puts it in line with data from tracheal cannula. At low ppM upper respiratory absorption is minimal, so data from nose and tracheal inputs are similar. At higher concentrations, tracheal input gives greater response.

Respiratory response of guinea pigs to ozone alone and with sulfur dioxide

This study was designed to utilize our guinea pig bioassay method for irritant response to address the question of whether or not ozone and sulfur dioxide appeared to react to form sulfuric acid in the respiratory tract. Animals were exposed to 0.2, 0.4, and 0.8 ppm of each gas alone and to the combination at concentrations of 0.4 and 0.8 ppm. In these experiments sulfur dioxide alone produced no statistically significant alterations in respiration. All concentrations of ozone produced an increase in respiratory frequency. At the two higher concentrations the increase in frequency was accompanied by a decrease in compliance. The response to the combinations was the same as the response to those levels of ozone alone. No sulfuric acid was detected in the chamber atmosphere. The biological data suggest that none was formed in the lung.

Respiratory response of guinea pigs to oil mists.

Respiratory function was measured in guinea pigs exposed for one hour to submicrometer oil mists. Five oils were used: medicinal grade mineral oil, laboratory grade paraffin oil, light lubricating oil, unused motor oil and used motor oil. The last three oils were also studied after having been reacted with sulfur dioxide. No alterations were produced by exposure to any of the oils at concentrations of 10 or 40 mg/m3. At concentrations above 200 mg/m3 both the reacted and unreacted light lubricating oil caused a decrease in compliance which remained throughout the post-exposure period. Although the average flow-resistance of the group was increased by the unreacted unused motor oil and by the reacted used motor oil, the variation in response was too great to make this response statistically significant. The fact that reaction of the oils with sulfur dioxide did not increase irritant action indicates that the reaction products with sulfur dioxide are not acutely irritant.

Response of Guinea Pigs to a Combination of Sulfur Dioxide and Open Hearth Dust

Measurement of alterations in the mechanical behavior of the lungs of guinea pigs may be used to assess the irritant potency of air pollutants. By examining the response to an irritant gas alone and in the presence of a known amount of particulate material it is possible to determine whether or not the particulate material has caused a potentiation of the response. This technique has been used to examine the effect of re-dispersed open-hearth dust on the response to sulfur dioxide. The open-hearth dust used was material obtained from electrostatic precipitators. The system used for re-dispersal of this material will be described. The open-hearth dust alone produced no detectable respiratory response even when used at a concentration as high as 7 mg/m3. It was also without effect on the response to several levels of sulfur dioxide. The findings were similar for an aerosol of iron oxide. This is in contrast to soluble iron salts which do potentiate the response to sulfur dioxide. These contrasting findings ...

The Irritant Potency of m-Terphenyl of Different Particle Sizes

Abstract The effect of homogeneous aerosols of m-terphenyl of 0.30, 0.65, 1.0, and 2.0 μ diameter on pulmonary-flow resistance of unanesthetized guinea pigs was studied. At equal mass concentration the irritant potency increased as the particle size decreased and the number of particles increased. A small increase in mass concentration for the smaller particles produced a greater increment in response than occurred when the large particles were used. The results were in agreement with earlier work1 on aerosols of zinc ammonium sulfate.