Total urinary arsenic has traditionally been used for assessing occupational exposure to inorganic arsenic. However, dietary arsenic, especially from seafood, may greatly influence this value. This paper describes a fast and convenient method for routinely measuring the combined amount of inorganic arsenic, methylarsonic acid, and dimethylarsinic acid, which are the major urinary metabolites after exposure to inorganic arsenic. Organic arsenic compounds of marine origin are not biotransformed to inorganic arsenic or methylated arsenic acids to any significance in the human body. They do not produce arsines when treated with the reducing agent in the proposed method and will therefore not interfere with the measurements. The sensitivity, accuracy, and precision of the proposed method are sufficient for the determination of concentrations of arsenic normally found in the urine of nonexposed persons. The method is based on a commercially available hydride generation kit attached to an atomic absorption spectrophotometer.

Key terms dimethylarsinic acid; exposure indicator; inorganic arsenic; methylarsonic acid; occupational exposure; occupational exposure; selective analysis; total urinary metabolite