MP5 Novel Methods for Bioaccumulation Assessment
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() POPs: A QSAR System for Creating PBT Profiles of Chemicals and their Metabolites.

Mekenyan, O. G.1, Dimitrov, S. D.1, Pavlov, T. S.1, Robinson, P.2, 1 Laboratory of Mathematical Chemistry, Bourgas As. Zlatarov University, Bourgas, Bourgas, Bulgaria2 Existing Substances Branch, Environment Canada, Gatineau, K1AOH3, Canada

ABSTRACT- The framework of a QSAR-based decision support system which provides a rapid screening of potential hazards, classification of chemicals with respect to risk management thresholds, and estimation of missing data for the early stages of risk assessment will be presented. At the simplest level, the framework is designed to rank hundreds of chemicals according to their profile of persistence, bioaccumulation potential and toxicity often called the POP (persistent organic pollutant) profile or the PBT (persistent bioaccumulative toxicant) profile. The only input data is the chemical structure. The POPs framework advances hazard identification by integrating a metabolic simulator that generates metabolic map for each parent chemical. Both the parent chemicals and plausible metabolites are systematically evaluation for metabolic activation and POPs profile. The persistence of studied parent chemicals is assessed by combining the requirements for calculated BOD (or half-lives) − using CATABOL system and the amount of stable metabolites. The determination of the B-profile of chemicals is based on the evaluation of the maximum bioccumulative potential determined by passive diffusion and reducing effect of the molecular size and flexibility, ionisation, biotransformation, etc. Finally, libraries of acute and chronic toxicity models are used to assess T-profile. The performance of the system for assessing B and T profile of chemicals has been used for categorization of chemicals on DSL.

Key words: metabolism, PBT profile, persistence, bioaccumulation

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