Toxicological evaluation of arsenic in edible seaweed, Hizikia species.

Young male Wistar rats were fed with chows containing marketed Hizikia preparation. Hizikia-arsenic could be absorbed at the rate comparable to arsenic trioxide, and accumulated primarily in blood. Intake and excretion of arsenic from Hizikia-diet reached a steady state within 4 days of administration as was the case of arsenic trioxide. Biological half-life in blood and urine was also essentially the same in the 2 groups. Rats kept for 3 weeks on the chows containing up to 20% Hizikia did not show significant growth retardation as compared with the controls, while those on 50% Hizikia-diet were markedly emaciated. In a 38-week feeding experiment, 4 groups of rats were given 20% Hizikia-diets made from various Hizikia preparations (final arsenic concentrations; 9, 16, 21 and 21 ppm, respectively). For positive controls, 2 groups were given arsenic trioxide diets (24 and 50 ppm as arsenic). Growth retardation was minimum both in Hizikia and arsenic groups with no relation to the arsenic dose. Changes in hematology, blood biochemistry and pathology of major organs and skin were also essentially negative in all groups. The maximum no-effect level observed in the present study was compared with the possible amount of arsenic taken via seaweed in mankind.