CORRELATION OF EFFECTS OF INHALED VERSUS INTRATRACHEALLY INJECTED METALS ON SUSCEPTIBILITY TO RESPIRATORY-INFECTION IN MICE

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Abstract
Effects of intratracheally administered air pollutant chemicals on susceptibility of mice to infection by aerosolized bacteria were compared with effects of the same chemicals previously studied by the inhalation route. Of 22 compounds previously studied by inhalation, CdSO4, CuSO4 and ZnSO4, which caused significantly increased mortality because of infection after a 3 h exposure to 1-2 mg/m3, showed large (.gtoreq. 40% over sham injected) mortality increases when administered by intratracheal injection at lung concentrations calculated to be equivalent to those achieved during inhalation exposures (0.6-1.2 .mu.g). Dose-effect curves were similar by the 2 routes. Compounds (5) caused a moderate (20-30%) enhancement in the mean excess mortality at concentrations of 2-3 .mu.g/animal. The remaining compounds, which showed no significant effect by inhalation, also showed no effect when given by intratracheal injection. Similar effects on susceptibility to lung bacterial infection were seen whether chemicals were deposited in the lung by inhalation or by intratracheal injection.