Estimating Relative Potency for Receptor-Mediated Toxicity: Reevaluating the Toxicity Equivalence Factor (TEF) Model

Putzrath, Resha M.; Dabt,

doi:10.1006/rtph.1996.1063

Cited by 44 publications

(42 citation statements)

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“…Equation 1 shows the usual expression for the mixture risk quotient (1,12,15,18) indicating that, under the assumption of concentration addition, the risk for exposure to a mixture can be expressed as the sum of the single risk quotients RQ x of all of the toxicants of concern. Equation 1 implies that several subthreshold (i.e., ineffective) exposures could have a cumulative adverse effect.…”

Section: Methodsmentioning

confidence: 99%

Including Transformation Products into the Risk Assessment for Chemicals: The Case of Nonylphenol Ethoxylate Usage in Switzerland

Fenner

Kooijman

Scheringer

et al. 2002

Environ. Sci. Technol.

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A method for applying the risk assessment approach using ratios of predicted environmental concentrations (PECs) and predicted no-effect concentrations (PNECs) to mixtures of parent compounds and their environmental transformation products is presented. Nonylphenol ethoxylates (NPnEOs) and a selection of their most relevant transformation products are investigated as a case study illustrating the method. The PEC values of NPnEO and its transformation products are calculated with a regional multimedia fate model including the transformation kinetics of the NPnEO degradation cascade. PNEC values are derived from a selection of toxicity data on NPnEO and its transformation products. The toxicity of the emerging mixture of NPnEO and its transformation products is then estimated under the assumption of concentration addition (similar mode of action). On this basis, PEC-to-PNEC ratios for the aquatic environment and the sediment are calculated for the individual components of the mixture and the mixture itself. For this purpose, average release rates of NPnEO and its transformation products from Swiss sewage treatment plants were used. While the PEC values of the individual components do not exceed the corresponding PNEC values, the risk quotient of the mixture in water is greater than 1. In sediment, the mixture does not exceed a risk quotient of 1. A combination of sensitivity and scenario analyses is employed to identify the upper and lower bounds of the results.

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Section: Methodsmentioning

confidence: 99%

Including Transformation Products into the Risk Assessment for Chemicals: The Case of Nonylphenol Ethoxylate Usage in Switzerland

Fenner

Kooijman

Scheringer

et al. 2002

Environ. Sci. Technol.

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“…3), activity was calculated based on the EC 20 values using REP range and the point of departure (Moore and Caux, 1997;Oris and Bailer, 1997;Putzrath, 1997;Villeneuve et al, 2000). When this method was applied, the H4IIE cells were found to be sufficiently sensitive to determine TCDD-EQs in sediment extracts.…”

Section: Tcdd-eq Calculationmentioning

confidence: 99%

AhR-active compounds in sediments of the Haihe and Dagu Rivers, China

Song

Jiang

et al. 2006

Chemosphere

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Total concentrations of compounds that can cause activation of the aryl hydrocarbon receptor (AhR) in extracts of river sediments from various locations in the Haihe and Dagu Rivers, Tianjin, China were determined by use of the in vitro H4IIE-luc cell line. AhR-active compounds were isolated from sediments by Soxhlet extraction, and the crude extracts were fractionated using a Florisil column into three Fractions. The response of samples was compared to the TCDD standard and expressed as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TCDD-EQs). Significant dioxin-like activity was observed in each sample. The TCDD-EQs in crude extracts of sediments (SCEs), as determined with the bioassay were 2-4 times greater than the sum of the TCDD-EQs of the eluent from fractions separated with a Florisil column. The results also showed that Fractions 2 and 3 contained most of the AhR-mediated activity. The results obtained by using the bioassay were compared with those of previous measurements of the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) and the structurally-similar AhR-active polychlorinated biphenyls (PCBs). It was determined that sediments from the Dagu River contained greater concentrations of TCDD-EQ than did sediments from the Haihe River except at Jingangqiao (location R3), which is associated with industrial activities in the adjacent densely populated area. The concentrations of TCDD-EQs, based on the EC 20 and the relative potency ranges, of SCEs ranged from 330 to 930 and 1200 to 13 900 pg TCDD-EQ g À1 dry wt in Haihe and Dagu Rivers, respectively.

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“…Of course, longer term in vivo study results are preferred as kinetics are not a factor in vitro and, in vivo, steady state is often not achieved in a few days when testing the persistent chemicals for which the TEF procedure was designed (Carpenter et at., 2002;Putzrath, 1997;Seed et al, 1995). EPA, 2000;2002c).…”

Section: Epa 2000)mentioning

confidence: 99%

“…TEFs do not have precise numerical values but are order of magnitude estimates (Putzrath, 1997 (Carpenter et aL, 2002). The ATSDR considers the TEF approach unsuitable for PCBs, due to their non-Ah receptor mediated toxicity and the fact that only 13 of 209 congeners have dioxin-like effects.…”

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confidence: 99%

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The Toxicology of Chemical Mixtures Risk Assessment for Human and Ecological Receptors

Sterner¹,

Robinson²,

Mattie³

et al. 2005

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REPORT DOCUMENTATION PAGE ublic reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the lata needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing ,is burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently alid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2 I. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)kir Force Materiel Command*** HEPB SUPPLEMENTARY NOTES ABSTRACT4ixtures of chemicals represent a concern in all areas of toxicology and a challenge to risk Issessors as most sites with environmental contamination, including Department of Defense sites, involve simultaneous or sequential exposures of multiple chemicals to human or ýcological receptors.A major concern with mixtures is that they may lead to outcomes (health effects) or increased toxicity (synergism) not expected from the risk 'haracterization of individual chemicals at the site.The focus of this literature review is :o examine the principles used to determine toxicity in chemical mixtures risk assessment for luman and ecological receptors at hazardous waste sites.This review provides an overview of 'urrent practices useful to a remedial project manager or risk assessor prior to their first ",hemical mixtures risk assessment. 5.SUBJECTTERMS

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Estimating Relative Potency for Receptor-Mediated Toxicity: Reevaluating the Toxicity Equivalence Factor (TEF) Model

Cited by 44 publications

References 0 publications

Including Transformation Products into the Risk Assessment for Chemicals: The Case of Nonylphenol Ethoxylate Usage in Switzerland

Including Transformation Products into the Risk Assessment for Chemicals: The Case of Nonylphenol Ethoxylate Usage in Switzerland

AhR-active compounds in sediments of the Haihe and Dagu Rivers, China

The Toxicology of Chemical Mixtures Risk Assessment for Human and Ecological Receptors

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