OBJECTIVETo study genetic damage of workers alone occupationally exposed to methotrexate (MTX) with three end-points.

METHODSThe blood samples from 21 workers exposed to MTX and 21 controls were detected with micronucleus test, comet assay, hprt gene mutation test and TCR gene mutation test.

RESULTSThe mean micronuclei rate (MNR) and mean micronucleated cells rate (MCR) in 21 workers were 10.10 per thousand +/- 0.95 per thousand and 8.05 per thousand +/- 0.75 per thousand, respectively, which were significantly higher than those (5.48 per thousand +/- 0.82 per thousand and 4.38 per thousand +/- 0.58 per thousand) in control (P < 0.01). The mean tail length (MTL) of 21 workers and 21 controls were (1.30 +/- 0.06) microm and (0.07 +/- 0.01) microm, respectively, there was significant difference between workers and controls (P < 0.01). But the difference between workers and controls for mean tail moment (MTM) was not significant (P > 0.05). The average mutation frequency (Mf-hprt) of hprt and (Mf-TCR) of TCR in workers were 1.00 per thousand +/- 0.02 per thousand and (6.87 +/- 0.52) x 10(-4), respectively, which were significantly higher than those [0.86 per thousand +/- 0.01 per thousand and (1.67 +/- 0.14) x 10(-4)] in control (P < 0.01).

CONCLUSIONThe genetic damage to some extent appeared in workers occupationally exposed to methotrexate.