Summary (1995-2000)

The aim of this program is to develop a comprehensive biological/toxicological and chemical testing protocol for assessing possible hazards at a Superfund site. This protocol will be used to characterize and quantitate the potential toxicity of two major classes of chemical wastes, namely oily (i.e. aromatic hydrocarbons, AHs) and wood-preserving wastes containing toxic halogenated aromatic hydrocarbon (HAH) contaminants. The program consists of four projects (three biomedical and one nonbiomedical) and administrative and training cores.

The research in this program focuses on the development and validation of the toxic equivalent factor (TEF) approach for risk assessment of AHs and HAHs. This technique involves all compounds being quantitatively ranked with respect to their potency relative to surrogate toxins such as benzo(a)pyrene and TCDD (tetrachlorodibenzo-p-dioxin), respectively. Such an approach is now being utilized for risk assessment by regulatory agencies worldwide.

Research regarding the response and target organ specific additive or nonadditive effects of PCB (polychlorinated biphenyl) congeners and mixtures on Ah receptor mediated signal transduction pathways comprises one of the biomedical projects of this program. This research uses both in vivo and in vitro models and will be used in the TEF approach to risk assessment. In a similar project, using diverse in vitro bioassay systems, research is directed at detection, prioritization, and prevention of developmental hazards due to certain target chemicals usually present at Superfund Sites. In this project, structure-dependent effects of chlorophenol and chlorophenol derivatives on mitochondrial function is also being investigated. Another biomedical project is exploring the genotoxicity of the complex mixtures extracted from wood-preserving waste and oily waste sites. In this project, DNA damage is assessed by 32P-postlabeling.

The one nonbiomedical project is concentrating on hazard identification of the complex mixtures of toxicants found at waste sites. Researchers are applying separation technologies, and then using existing bioassays, to define the most hazardous fractions contained in the mixture. Biological testing will provide data to define the immunotoxic, genotoxic, developmental, and neurotoxic potential of environmental samples.

This program is supported by administrative and training cores. Outreach activities for the program include involvement with community groups, regulatory agencies, and the industrial populace. Community outreach is facilitated by the development of fact sheets, which are also distributed to government regulators. Public meetings and an outreach program aimed at the primary and secondary education level will also help to increase public awareness. Investigators at Baylor University are also involved in collaborative research efforts within this program.