Donald G. Barnes

The international toxicity equivalency factor (I-TEF) method of risk assessment for complex mixtures of dioxins and related compounds☆

Abstract The International Toxicity Equivalency Factor (I-TEF) method of risk assessment is an updated interim procedure for estimating the risks associated with exposures to complex mixtures of chlorinated dibenzo-p-dioxins and dibenzofurans (CDDs and CDFs). The I-TEF approach facilitates risk communication internationally by reducing large volumes of analytical data into a single number-International Toxicity Equivalents (I-TEQ). The I-TEF method has been officially adopted in Canada, the Netherlands, the Nordic countries, the United Kingdom, and the United States. As a result, the I-TEF method represents an improvement in an already useful risk assessment/regulatory tool.

Interim procedures for estimating risks associated with exposures to mixtures of chlorinated dibenzodioxins and -dibenzofurans (CDDs and CDFs)

Abstract A set of weighting factors is proposed for expressing the toxicity of mixtures of CDDs/CDFs in terms of an equivalent amount of 2,3,7,8-TCDD. The factors are applied to a variety of environmental samples and the results compared to those obtained using a number of alternative factors which have been proposed.

The international toxicity equivalency factor (I‐TEF) method for estimating risks associated with exposures to complex mixtures of dioxins and related compounds∗

The International Toxicity Equivalency Factor (I‐TEF) method of risk assessment is a revised interim procedure for assessing the risks associated with exposures to complex mixtures of chlorinated dibenzo‐p‐dioxins and dibenzofurans (CDDs and CDFs). This updated scheme was developed by a working group of the North Atlantic Treaty Organizations Committee on the Challenges of Modern Society and has been officially adopted by the U.S. Environmental Protection Agency (EPA), Canada, Ontario Ministry of the Environment, the Nordic countries, the Netherlands, and the United Kingdom. Prior to the development of the I‐TEF method, at least ten slightly different schemes had been used throughout the world which complicated communication among scientists and regulatory agencies concerning the toxicological significance of complex mixtures of CDDs and CDFs. The I‐TEF approach facilitates risk communication internationally by reducing large volumes of analytical data into a single number‐International Toxicity Equivale...

Toxicity equivalents and EPA's risk assessment of 2,3,7,8-TCDD

Toxicity equivalent factors (TEFs) have proved useful in estimating the toxicity of complex mixtures of chlorinated dibenzo-p-dioxins and dibenzofurans (CDDs/CDFs). An international consensus has formed around a specific set of TEF values as interim solution for addressing environmental contamination by CDDs/CDFs. This procedure capitalizes on the congener-specific analytical results that are more routinely available in recent years. The TEF approach should be updated as necessary and replaced by more definitive bioassay approaches as soon as practicable. In an independent activity, the USEPA considered a proposal to change (reduce) the cancer potency ascribed to 2,3,7,8-TCDD by a factor of 16. The recommendation was based upon an analysis of the literature and the Agencys earlier risk assessment. The proposal was reviewed by the Science Advisory Board, a group of outside scientific advisors. Subsequently, the Agency decided against making any changes in its assessment at this time. However, it is likely that a reassessment will be conducted shortly that will incorporate new data and a new approach to estimating of cancer risks posed by 2,3,7,8-TCDD.

Health Hazard Assessment for Chlorinated Dioxins and Dibenzofurans Other Than 2, 3, 7, 8-Tcdd:

EPA is faced with the need to perform health risk assessments of environmental materials containing mixtures of chlorinated dioxins and -dibenzofurans. Preferably, such an assessment must be based on the direct evaluation of chronic health effects of the mixture or on a knowledge of the toxic effects of each of the components. In the absence of such data, the authors have developed two pragmatic approaches that can reasonably be applied to mixtures such as flyash or contaminated soil. The details of these approaches, viewed as interim procedures, are compared and contrasted with those used by other regulatory and public health authorities.

Reexamination of data used for establishing toxicity equivalence factors (TEFs) for chlorinated dibenzo-p-dioxins and dibenzofurans (CDDs and CDFs)

Abstract Recent literature reports on the relative toxicity and pharmacokinetics of CDDs and CDFs were examined in order to estimate their impact on current toxicity equivalence factors (TEFs) for chlorinated dibenzo- p -dioxins (CDDs) and -dibenzofurans (CDFs).

Assessing TCDD emissions from municipal waste combustors

Abstract The United States Environmental Protection Agency has sampled and analyzed the TCDD emissions from five municipal waste combustors and concluded that the levels do not represent present a public health risk.

Recent USEPA actions related to dioxins

Abstract Events over the past 15 years led to USEPAs development of a Dioxin Strategy, which is being implemented under the National Dioxin Study. This work, as well as recent regulatory actions, are reviewed.

A status report on the U.S. national dioxin study

Abstract In 1983, the US Environmental Protection Agency (EPA) embarked on an extensive investigation of the presence and extent of contamination of the national environment by CDDs/CDFs. This status report is a prelude to a final report to be delivered to the US Congress in December, 1985.