ABSTRACT
<p><b>OBJECTIVE</b>To assay the carcinogencity of water and organic extracts of birch wood dust.</p><p><b>METHODS</b>One stage and two stage model of mouse lung tumor by short-term induction test were used.</p><p><b>RESULTS</b>In the one stage experiment, no significant difference of the incidence of mice lung tumors was observed between different dosage groups of water extracts and organic extracts. In the two stage experiment, the tumor incidence and the average number of tumor per mouse in three dosage groups treated with the water extracts(1, 2, 4 g/kg) were 4.08% and 0.04, 8.33% and 0.15, 14.30% and 0.24 respectively with dose increment. There was a significant dose-response relationship between them(P < 0.05), and the tumor incidence and the average number of tumor per mouse in 4 g/kg group were significantly higher than those in the control group and 1 g/kg group and its one stage group(P < 0.05). The tumor incidence and the average number of tumor per mouse induced by organic extracts were higher with increasing dose, but no significant difference among groups was found (P > 0.05).</p><p><b>CONCLUSION</b>Both extracts of birch wood dust may be initiators, and carcinogenic effect of the water extract is stronger than that of the organic extract.</p>