Abstract: OBJECTIVE: To evaluate the mutagenicity and pollution indexes of mercury,arsenic, formaldehyde and their combinations in Vicia faba root tip cells. METHODS: Cells treated with distilled water were used as negative control group,and with potassium dichromate (50 mg/L) as positive control group. The micronucleus assay of Vicia faba root tip cells were used to determine genotoxicity after exposure to mercury (0.001-0.03 mg/L),arsenic (0.01-0.3 mg/L),formaldehyde (0.9-7.2 mg/L) and combined pollution (MIX I,MIX Ⅱ,MIX Ⅲ). Pollution indexes were calculated. Cells exposed to water or to potassium dichromate (50 mg/L) were used as negative and positive controls,respectively. RESULTS: When the concentration of mercury was ≥0.009 mg/L,arsenic ≥0.3 mg/L, formaldehyde ≥3.6 mg/L in the water,the micronucleus rate were significantly higher compared with the negative control group,respectively (P<0.05). There were four kinds of combination,included mercury-arsenic;mercury-formaldehyde; arsenic-formaldehyde;mercury-arsenic-formaldehyde. In group MIX I,the micronucleus rate of mercury-arsenic and mercury-formaldehyde were significantly higher compared with the negative control group,and also the mercury, arsenic,formaldehyde single exposure,respectively (P<0.05). In group MIX Ⅱ and Ⅲ,The micronucleus rate of all these four combinations were significantly higher compared with the negative control group,and the mercury, arsenic,formaldehyde single exposure,respectively (P<0.05). CONCLUSION: Mercury (≥0.009 mg/L), arsenic (≥0.3 mg/L),formaldehyde (≥3.6 mg/L) induced high frequency of micronucleiin Vicia faba root tip cells. Exposure to combined pollutants induced higher frequency of micronuclei than to single pollutants in varying degrees. There was a certain dose-response relationship between the exposure doses and micronucleus rates.

Key words: mercury, arsenic, formaldehyde, combined pollution, Vicia faba root tip, micronucleus frequency