Human alveolar deposition of 4 micron teflon particles

On two occasions ten healthy men inhaled with maximally deep inhalations at 0.5 1/sec a test aerosol of 4 micron teflon particles tagged with 111In. Radioactivity in the lungs was measured a few min, 24 hr, and 2, 3, and 4 days after inhalation. Retention decreased greatly between the measurements performed a few min and 24 hr after inhalation, but was similar in measurements 1 to 4 days after inhalation. Among individuals, retention varied considerably 1 to 4 days after inhalation (by a factor of 2), but the retention in each individual subject was uniform. Measuring the retention of a radioactively tagged test aerosol 1 day after inhalation, and regarding this retention as alveolar deposition, might be of value in preventive measures against certain toxic dusts.