Relative potencies of individual polychlorinated dibenzo-p-dioxin, dibenzofuran, and biphenyl congeners and congener mixtures based on induction of cytochrome P4501A mRNA in a rainbow trout gonadal cell line (RTG-2)
- Univ. of Wisconsin, Madison, WI (United States)
Cytochrome P450-catalyzed enzyme activity in cell culture was investigated as a bioassay for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents in environmental mixtures of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofuran (PCDF), and biphenyl (PCB) congeners. A problem with the use of enzyme induction is that certain congeners are unable to induce P4501A enzyme activity to the same maximal level as TCDD. The authors sought to eliminate this problem by measuring mRNA induction rather than enzyme activity. Rainbow trout gonadal cells (RTG-2) were exposed to PCDD, PCDF, and PCB congeners and congener mixtures, and induction of cytochrome P4501A mRNA was measured. A high level of induction in cells treated with only a medium change was seen and was due to a component of the fresh medium, 2,3,7,8-Substituted PCDD and PCDF congeners and four-non-ortho-substituted PCBs caused significant induction. Toxic equivalency factors determined in RTG-2 cells were generally higher than those in rainbow trout early life stages. Rainbow trout gonadal cell (RTG-2) bioassay TCDD equivalents (TEqs) for three environmental extracts were lower than predicted by addition of individual congener TEqs, and the synthetic congener mixture acted additively.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 483700
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 15, Issue 12; Other Information: PBD: Dec 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Development of toxic equivalency factors for PCB congeners and the assessment of TCDD and PCB mixtures in rainbow trout
Evaluation of 2,3,7,8 specific congener and toxic potency of persistent polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in cetaceans from the Mediterranean Sea, Italy