Autoradiographic studies on the distribution of arsenic in mice and hamsters administered 74As-arsenite or -arsenate.

Whole-body autoradiography in combination with other determinations of tissue levels of 74As-arsenic in mice, 5 min. to 30 days after intravenous injections of 74As-arsenite (As III) or -arsenate (As V), showed higher organ concentrations and whole-body retention of arsenic in the As III mice as compared to the As V mice. Only the kidneys (at short time intervals) and the skeleton had higher levels in the As V mice as compared to the As III mice. The skeletal accumulation of As V is probably due to the resemblance of the arsenate to phosphate, so that arsenate may substitute for phosphate in the apatite crystal. The long-term retention of arsenic was most apparent in hair and skin, squamous epithelium of the upper gastrointestinal tract (oral cavity, oesophagus, and the oesophageal part of the stomach mucosa), the epididymis, thyroid, lens and skeleton. The accumulation in hair, skin and the upper gastrointestinal tract may be ascribed to a binding to keratin, the content of which is high in squamous epithelia. The distribution of arsenic in golden hamsters was similar to that found in mice. The significance of the findings in relation to reported adverse effects of inorganic arsenic is discussed.