Arsenic compounds contained in sea foods have raised public health concerns, because their chronic exposure through dietary intake may increase cancer risk. In the present study, we investigated the in vitro genotoxicity of two inorganic arsenics (arsenite; As[III], arsenate; As[V]) and three organic arsenics (monomethylarsonic acid; MMAA, dimethylarsenic acid; DMAA, trimethylarsine oxide; TMAO) using mouse lymphoma Tk assay (MLA). In the standard MLA with 3 h treatment, exposure to As[III] and As[V] significantly induced Tk-mutants. The genotoxicity of As[III] was over 50-times greater than that of As[V]. Among organic arsenics, on the other hand, only DMAA showed weak genotoxicity with 3 h treatment at high doses. In the 24 h treatment MLA, DMAA and TMAO weakly induced Tk-mutants. These results indicate that inorganic arsenics rather than organic arsenics should be considered for genotoxic risk. We discussed the genotoxic risk of arsenic compounds through dietary intake.
