Cellular responses to tritium exposure in rainbow trout (Oncorhynchus mykiss): HTO and OBT-spiked feed exposure experiments

Purpose: Evaluation of biological effects in fish exposed to tritium. Materials and Methods: Rainbow trout (Oncorhynchus mykiss) were exposed to tritiated water (HTO) or organically-bound tritium (OBT) spiked feed. The HTO exposure study was conducted using a tritium activity concentration of 7000 Bq/L and the OBT exposure study was conducted using a tritium activity concentration of 30000 Bq/L. Fish in both studies were expected to be exposed to similar tritium levels assuming 25% incorporation of the tritiated amino acids found in the feed. Results and Conclusions: Following 140 days in vivo exposure to HTO, the HTO and OBT activity concentrations in muscle tissue were 7920±113 and 1550±103 Bq/L, respectively. The control fish HTO and OBT activity concentrations were 490±13 and 498±182 Bq/L, respectively. Liver, heart, spleen, kidney and brain cells did not show statistically significant differences in viability and DNA double strand break repair activity compared to control cells. Membrane fatty acid composition analysis was conducted on the liver cells and no effects of HTO exposure could be detected. Following 140 days in vivo exposure to OBT, the HTO and OBT activity concentrations in muscle tissue were 47±6 and 39370±4210 Bq/L, respectively. The control fish HTO and OBT activity concentrations were 30±6 and 220±56 Bq/L, respectively. Viability and DNA double strand break repair activity were not statistically different to controls in liver, heart, spleen, kidney and brain cells. Changes, however, were noted in the fatty acid composition of liver and muscle tissues. (author)