Biological effects of chrysotile after SO2 sorption. II. Effects on alveolar macrophages and red blood cells.

An experimental study has been carried out using different biological and biochemical in vivo and in vitro tests for assessing the toxicity of natural UICC (A) chrysotile and SO2-sorbed UICC (A) chrysotile and for detecting a possible synergistic effect. For in vivo studies, rabbits received an intratracheal injection of chrysotile fibers suspended in physiological saline (PS). The control group received only PS; all animals were sacrificed after 68 hr. The alveolar free cells were harvested by pulmonary lavage. The results have shown that chrysotile induces a decrease in the free cell population but there was no significant difference in the number of viable cells or in the nature of cells harvested between the two chrysotile groups. Enzymatic activities of the alveolar macrophages from animals injected with SO2-sorbed chrysotile showed a significant increase of the enzymes LDH and acid phosphatases. The LDH increase could be related to the affinity of the enzyme regarding some chemical forms of SO2. In vitro studies using alveolar macrophages harvested by pulmonary lavage have shown no differences between the two chrysotile groups when cell viability and enzyme release were studied. The toxic effect was due to chrysotile fibers (decrease of 38% in cell viability and increase in cellular enzyme release when compared with control). When rabbit red blood cells were used, both natural and SO2 chrysotile fibers showed the same hemolytic activity. The failure to detect high differences between the two chrysotile groups may be related to the chemical form of sorbed SO2.