Biotransformation of As(III) to As(V) and arsenic tolerance.

The paper deals with excretion of As(III) and As(V) in the urine of mice exposed to a toxic concentration of As(III) (250 mg/1) in drinking water. After the exposures of 2, 6, and 8 days, the mice were given i.m. a solution of 74As(III) labeled sodium arsenite in a dose of 1.3 mg As(III)/kg b.w. and an activity of 3 muCi/l ml. After the sacrifice of the animal, the urine was drawn off directly from the bladder. The urine samples were subjected to separation of As(III) from As(V) by using a paper radiochromatography technique. The results showed that unexposed control mice excreted one-half of the administered As(III) in the form of As(V). Mice exposed to arsenic in drinking water exceted already, after 2 days of exposure, four-fifths of the applied As(III) in the form of As(V), after 4 days of exposure the proportion of As(V) was more than 95%, and after 8 days of exposure only traces of As(III) were present. The authors discussed the possibility of the biotransformation of As(III) to As(V) on arsenic tolerance.