Uptake of tritium from tritiated water exposure in the medaka and zebra fish and estimation of DNA damage due to tritium

Abstract

In the present work, the biological effect of tritium on tissue and erythrocyte DNA of fresh water fishes was estimated by the comet assay during long term exposure of tritiated water (HTO). Medaka or zebra fishes were exposed to HTO (146-1042Bq/ml) added to an aquarium for 10-26 days and the uptake, retention and release of tritium in fish body were investigated. Total tritium per g fresh weight of medaka equilibrated rapidly, around 40min after the start of exposure, to about 50% of the aquarium water concentration while organically bound tritium reached only 1% of the aquarium water concentration after 10 days exposure. The biological half time of tritium in the fishes transferred to fresh water after 26days exposure was 14 min. The effect of long term exposure to low dose tritium on fresh water fish was examined using medaka fed in HTO (2Bq/ml) containing aquarium for 232 days. No significant effect was observed in the liver cell.