Health Effects of Fine- and Coarse-Mode Particulate Matter: Exposures by Inhalation and Intratracheal Instillation

摘要

Because coarse mode particles are rarely studied in their existing size ranges (greatest mass about 5-7 micrometers, aerodynamic diameter), the authors investigate the effects of four such particles, quartz, ferric oxide, calcium carbonate, and sodium feldspar, on host defenses against bacterial pulmonary infection. Mice which received intratracheal instillations of 10, 33, and 100 micrograms/mouse were exposed within an hour to aerosols of viable Streptococcus, and pneumonia-induced mortality was measured. At 33 and 100 micrograms/mouse, all particles significantly increased mortality. At the lower dose, only Fe203 caused a significantly increase in mortality. To evaluate potential delayed effects, mice were challenged with the bacteria 24 h after exposure to 100 micrograms particles/mouse. Delaying the challenge did not significantly alter the response, except for the sodium feldspar group for which a partial recovery was observed.