1984 年 22 巻 4 号 p. 261-277
Retention and clearance of chromium in the lung, heart, liver, kidney, spleen, plasma and blood cells were investigated in rats after a single exposure to either hexavalent chromium (Cr (VI)) or trivalent chromium (Cr (III)) aerosols with different chromium levels (7.415.9 mg Cr/m3) and different particle size distributions. The investigation was carried out from 0.5 h up to 7 days after exposure.
Exposure to Cr (VI) aerosol showed more toxic effects than exposure to Cr (III). Initial cocentrations of lung chromium were in proportion to the exposure levels for each inhalation series of Cr (VI) or Cr (III) compounds. Chromium clearance from the lungs in the Cr (VI) groups was dependent on the size distribution of the aerosol particles. In the groups exposed to smaller Cr (VI) aerosol particles the lung chromium clearance showed two phases. The biological half-time of the first phase was 31.5 h and that of the following second phase was 732 h. Chromium clearance from lungs exposed to larger particles of Cr (VI) or to Cr (III) aerosols showed a single phase, the biological half-time of which ranged from 151 to 175 h. Chromium transport from the lungs into the blood, kidneys and liver was more rapid in the Cr (VI) groups than in the Cr (III) groups. In the former groups, the kidneys and liver also showed two-phase chromium clearance.
These results suggest that considerable amount of chromium deposited in lung alveoli as the hexavalent form are rapidly transfered into the blood and taken up by erythrocytes or visceral organs, especially the liver and kidneys, before being reduced to the trivalent state.
