This is a decision support system classifying chemicals according to their profile of persistence, bioaccumulation and toxicity often called the POP (persistent organic pollutant). This is the only available expert system predicting PBT profile of the chemicals accounting for their stable degradants. 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 evaluated for their bioaccumulation and toxicity profile. Thus, the system meets the requirements of the legislation in Europe, North America and Japan, for assessing the hazardous behavior of chemicals (especially pesticides) by taking into account the properties of their stable environmental metabolites. The persistence of studied parent chemicals is assessed by combining the requirements for calculated biological oxygen demand, BOD (or half-lives) – using CATALOGIC 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 of Environment Canada. The POPs system is now in use in US EPA, Environment Canada, NITE Japan, Danish EPA and major industries.