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