TCDD‐Like activity of 2,3,6,7‐tetrachloroxanthene in rainbow trout early life stages and in a rainbow trout gonadal cell line (RTG‐2)

Abstract

AbstractFish in many areas are contaminated with 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) and related polychlorinated dibenzo‐p‐dioxin (PCDD), dibenzofuran (PCDF), and biphenyl (PCB) congeners. Other chemicals may also be present that act through the same mechanism. 2,3,6,7‐Tetrachloroxanthene (TCX) has been found to be an interference in PCDD and PCDF analyses and may occur in sediments near pulp and paper mills. However, the toxicology of TCX has not been studied in any species. This study sought to determine whether TCX causes TCDD‐like effects in two fish systems, rainbow trout early life stages and rainbow trout gonadal cells (RTG‐2) in culture. 2,3,6,7‐Tetrachloroxanthene caused rainbow trout sac fry mortality secondary to blue sac syndrome, identical to that caused by TCDD, and was similar in potency to TCDD for causing cytochrome P4501A mRNA induction in RTG‐2 cells and sac fry mortality in rainbow trout, with toxic equivalency factors of 1.09 to 2.29. These results suggest that TCX may pose a risk to feral fish in contaminated areas even at low concentrations.