Effect of MWCNT on alveolar cell number and on phagocytosis cells. Rats were treated by 1, 10 or 100 μg of CNT. After BAL at d1, d7, d30, d90 and d180, total cells were quantified. Results show a significant induction of cells at d7 and d180. Results are the mean of ± SD obtained on 6 rats. * Significantly different (p < 0.05) from control group.