PARENT SESSION

WP3 Aquatic Toxicology
Ballroom G, Level 4
2:10 PM - 5:30 PM, Wednesday, 12 November 2003
Chair: Phillips, Todd ,

(427) Distribution, kinetics and effects of ¹³¹I labelled radiopharmaceuticals in the trout.

Adam, C.¹, Carel, D.¹, Cavalié, I.¹, Ksas, B.¹, Buet, A.¹, Garnier-Laplace, J.¹, Casellas, C.², ¹ IRSN, St Paul Lez-Durance, France² UMR5569, Montpellier, France

ABSTRACT- In the framework of the French National Program PNETOX2-ENIMED, radioisotopes liable to be used in the labelling of radiopharmaceuticals were measured in French sewage treatment plants effluents and their potential accumulation and effects on the rainbow trout were experimentally assessed. ¹³¹I was the main radioisotope detected. Consequently, two widely used ¹³¹I labelled compounds were tested : NaI and MIBG (m-iodobenzylguanidine), the last one being characterized by a high toxicity (LD₅₀ in mice : 2.5 g.g^-1) while no NaI toxicity has been shown. Three groups of 50 fish were constituted, two were injected intraperitoneously with 2 L g^-1 of NaI or MIBG, while the control group was injected with a saline solution. For the contaminated groups, the resulting whole-body radioactivity was 2000 Bq. g^-1, the MIBG concentration being of 0.4 g.g^-1. To study the distribution and kinetics of radiolabelled molecules, organs and tissues were dissected to measure ¹³¹I concentrations while autoradiography was used to visualize its distribution. A range of biomarkers were measured to assess the potential toxicity, such as biomarkers of oxidizing stress (glutathione peroxidase, catalase, superoxide dismutase, metallothioneine) and of genotoxicity (micronuclei). The results show that a two-compartment model can be used to describe whole-body NaI and MIBG elimination, the biological periods being of 19 and 1.4 days for NaI and of 15 and 2.2 days for MIBG. For NaI, ¹³¹I was mainly associated to the thyroid follicles, 95 % of the relative concentration being located in the lower jaw at the end of the experiment (at day-21). For MIBG, the greatest concentration was measured in the bile and the digestive tract, the storage organ being the kidney. No genotoxicity could be evidenced for these concentrations. An induction of MT was significant in the liver at day-21, indicating the cytoxicity and/or oxidizing stress induced by this compound.

Key words: iodine-131, Radiopharmaceuticals, fish, pharmacokinetics