Development of Bioassays and Approaches for the Risk Assessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin and Related Compounds

Safe, Stephen

doi:10.2307/3431745

Cited by 20 publications

(23 citation statements)

References 47 publications

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“…Our protocol is based on the original method of Schwirzer et al 39 , as modified and applied by Thiem et al [40][41][42] for routine dioxin screening, which is based on the pioneering work of Donato et al 43,44 , Safe 45 and Tillitt et al 46 . It is regularly applied at the Institute for Environmental Research, RWTH Aachen University, Aachen, Germany and at the Food and Veterinary Institute Braunschweig/Hannover, Lower Saxony State Office for Consumer Protection and Food Safety (LAVES), Germany.…”

Section: Development Of the Protocolmentioning

confidence: 99%

Determination of the CYP1A-inducing potential of single substances, mixtures and extracts of samples in the micro-EROD assay with H4IIE cells

et al. 2015

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This protocol describes a quantitative and robust 96-well-plate-reader-based assay for the measurement of ethoxyresorufin-O-deethylase (EROD) activity using the rat hepatoma cell line H4IIE. The assay can be used to determine the cytochrome P450 subfamily 1A (CYP1A)-inducing potential of single substances, as well as of mixtures and extracts of samples. It is based on the aryl hydrocarbon receptor (AhR)-mediated induction of cytochrome P450 enzymes (subfamily 1A) in cells after exposure to dioxins and dioxin-like compounds. One enzymatic reaction catalyzed by CYP1A is the deethylation of the exogenous substrate 7-ethoxyresorufin to the fluorescent product resorufin, which is measured as EROD activity in the assay. The CYP1A-inducing potential of a sample can be reliably quantified by comparing the EROD activity with the concentration-response curve of the standard substance 2,3,7,8-tetrachlorodibenzo-p-dioxin, which can be detected at concentrations down to the picogram per liter range. A researcher familiar with the procedure can process up to 160 samples with four wells each within 3 d. The series described uses four plates with three concentrations per sample, which can be easily scaled to accommodate different sample sizes.

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Section: Development Of the Protocolmentioning

confidence: 99%

Determination of the CYP1A-inducing potential of single substances, mixtures and extracts of samples in the micro-EROD assay with H4IIE cells

et al. 2015

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“…some of the non-coplanar, phenobarbital-like inducers: 2,5,2 0 ,5 0 -TCB and 2,4,5,2 0 ,4 0 ,5 0 -HCB (Safe 1990(Safe , 1993]. The unsubstituted dibenzodioxin does not bind to the Ah receptor and it was not carcinogenic on bioassay (NTI 1979a).…”

Section: Tum Our Promotion Studiesð Rat Livermentioning

confidence: 96%

Animal studies addressing the carcinogenicity of TCDD (or related compounds) with an emphasis on tumour promotion

Dragan¹,

Schrenk²

2000

Food Additives and Contaminants

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Dioxin and certain structurally related compounds increase the incidence of liver neoplasms in rodents upon chronic bioassay. Short-term studies indicate the lack of direct DNA-damaging e ects including covalent binding to DNA; however, secondary mechanisms may be important in the observed carcinogenicity as these chemicals a ect a number of pathways necessary for maintenance of normal growth control and di erentiation status. Studies with TCDD in the mouse skin support a lack of initiating activity but an ability to promote the growth of previously initiated lesions indicative of a promoting agent. Mouse skin tumour promotion studies indicate that Ah receptor activation may be involved in promotion by TCDD and selected structurally related compounds. While the mechanism of carcinogenicity induced by TCDD is unknown, the processes involved have a no-e ect level, which in the rat liver is at an exposure level below 10 ng TCDD/kg/ day. At least for the rodent liver, the relative e ective dose for cytochrom e P450 induction is not a good indicator of promotion potency. Studies on liver tumour promotion in the female rat liver support a nongenotoxic mechanism for the induction of neoplasms by TCDD. The ability of TCDD to enhanc e proliferation and inhibit apoptoti c processes in focal hepatic lesions further supports an indirect mechanism of carcinogenicity.Carcinog enicity studies with TCDD Kociba et al. (1978) performed a lifetime feeding study with 1, 10, and 100 ng TCDD/kg/day to male and female Sprague± Dawley rats. The results of the 2-year bioassay on the incidence of tumours induced by feeding TCDD to Sprague± Dawley rats form the primary basis for the regulatio n of TCDD as a known animal carcinogen and possible human carcinogen (IARC 1987). The female rat liver was the primary target site as assessed by a Dow Chemical Co. pathologist and independently by R. Squire (Kociba et al. 1978). The Kociba study demonstrat ed hepatic hyperplastic nodules at an incidence of 8/86, 3/50, 18/50, and 23/50 for control, 1, 10, and 100 ng/kg/day respectively. Similarly, the incidence of hepatocellular carcinomas in female rats was 1/86, 0/50, 2/50, and 11/50 for these treatmen t groups from dietary levels of backgroun d, 22, 210, and 2200 ppt, respectively, for these groups. Since the criteria for assessment of hepatic lesions had evolved after the original determination , a re-evaluati on of the hepatoproliferative lesions in the female rat liver of TCDD-treated animals was performed by the Pathology Working group (Goodman and Sauer 1992). This re-evaluation detected a similar trend for hepatic tumour incidence as previously reported (Kociba et al. 1978), but a lower incidence was noted in the re-evaluation than in the original study; however, a clear increase in the incidence of combined liver tumours (adenomas and carcinomas) was observed in the middle (9/50) and high dose (14/50) groups compared with the control (2/86). Four hepatocellular carcinomas were observed and these were well di erentiated, while the majority ...

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“…Next to enzymatic assays (AHH assay and EROD assay) (Safe, 1993 ), the most popular cell-based assay to screen for dioxin and dioxin-like compound in food-feed is the in vitro luciferase bioassay called CALUX (Chemically Activated LUciferase gene eXpression) . It is a recombinant receptor/reporter gene assay system using several aspects of the AhR-dependent mechanism of action (Aarts et al ., 1995 ;Garrison et al ., 1996).…”

Section: Cell-based Assaysmentioning

confidence: 99%

Screening and confirmatory methods for the detection of dioxins and polychlorinated biphenyls (PCBs) in foods

Focant

Eppe

2013

Persistent Organic Pollutants and Toxic Metals in Foods

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Development of Bioassays and Approaches for the Risk Assessment of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin and Related Compounds

Cited by 20 publications

References 47 publications

Determination of the CYP1A-inducing potential of single substances, mixtures and extracts of samples in the micro-EROD assay with H4IIE cells

Determination of the CYP1A-inducing potential of single substances, mixtures and extracts of samples in the micro-EROD assay with H4IIE cells

Animal studies addressing the carcinogenicity of TCDD (or related compounds) with an emphasis on tumour promotion

Screening and confirmatory methods for the detection of dioxins and polychlorinated biphenyls (PCBs) in foods

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