Previous experiments with the sheep model of
silicosis have demonstrated a reduction of the pathological activity of
quartz after treatments with
aluminum lactate (Al-lac), such as Al-lac pretreatment of intratracheally injected
quartz or Al-lac inhalation of
quartz-exposed animals. Preliminary data also suggested a more effective alveolar clearance of
quartz treated with Al-lac. The present study was undertaken to fully document the effect of Al-lac treatments on the pulmonary retention of
quartz. Sheep (on average, 27 per group) received a single injection in the tracheal lobe of either 100 mg/100 mL of alpha-
quartz, 100 mg/100 mL of alpha-
quartz followed by Al-lac inhalations at 1-month intervals, or 100 mg/100 mL of alpha-
quartz Al-lac pretreated in vitro. Samples of lung parenchyma were analyzed at 2, 6, and 10 months after the injection. The
quartz concentration in each sample was measured using the X-ray diffraction method. The concentrations were expressed in micrograms of
quartz per milligram of dry lung parenchyma. The geometric mean concentrations in each of the three groups at 2 months were statistically different (ANOVA of the log values; p = .016) as well as at 6 months (ANOVA of the log values; p = .001). Al-lac clearly reduced the pulmonary retention of
quartz. Both modalities of Al delivery were equally effective in clearing
quartz up to 2 months, which may explain the documented reduction in pathological activities after in both forms of
therapy. However,
quartz soaked in Al-Lac
solution was more effective than inhalation of Al-lac after
quartz exposure. The half-life of both native
quartz and
quartz Al-
lactate inhaled was 5.05 and 4.99 months, respectively, while it was 3.1 months for Al-treated
quartz. Al-lac inhalations after the second month of exposure do not significantly affect the rate of clearance of deposited
quartz.