BIOACCUMULATION OF ORGANOTIN COMPOUNDS IN THE RED-SEA BREAM (PAGRUS-MAJOR) BY 2 UPTAKE PATHWAYS - DIETARY UPTAKE AND DIRECT UPTAKE FROM WATER

The bioaccumulation and elimination of organotin compounds in Pagrus m ajor during dietary uptake and/or direct uptake from water were studie d. When tributyltin (TBT) and triphenyltin (TPT) compounds were accumu lated in fish from seawater and from feed simultaneously, about one-qu arter of the bioaccumulation was due to the dietary uptake. The biomag nification factors (BMFs) were 0.26 to 0.38 for TBT and 0.57 for TPT. BMF was not significantly altered by the concentration nor the species of chemicals in the feed. The assimilation efficiency of ingested TBT and TPT was 9.5 to 12.7 and 19.6%, respectively, and percentage reten tion was 24.2% for TBT and 60.1% for TPT. The BMF, percentage retentio n, and assimilation efficiency of TBT were all lower than those of TPT , suggesting that TPT compounds are more easily accumulated by dietary uptake than TBT compounds. Compared to PCBs and methylmercury chlorid e, the assimilation efficiency and the percentage retention of organot in compounds were low. These lower values imply that the risk of bioac cumulating the ingested organotin compounds might be smaller than for PCBs and methylmercury chloride.