PARENT SESSION
MA4 - Biotransformation / Metabolism / Degradation
Chair: Zepp, Richard1, 1 U.S. EPA, Athens, GA
8:00 AM to 12:00 PM - Monday, 18 November 2002
Room Ballroom F
(194) Predicting the biodegradability of chemical substances and its application to Premanufacture Notices.
Tunkel, Jay1, Boethling, Robert*,2, Howard, Philip1, Aronson, Dallas1, 1 Syracuse Research Corporation, Syracuse, New York, USA2 U.S. Environmental Protection Agency, Washington, DC, USA
ABSTRACT- In the US, chemical substances other than pesticides and drugs are regulated by the EPA under the Toxic Substances Control Act (TSCA). Substances not yet in commerce are subject to Premanufacture Notification (PMN) requirements, which do not include a battery of standard tests. Biodegradability is a key parameter in the assessment of potential risk for PMN substances, as well as many other applications in pollution prevention (P2). Due to the lack of submitted data, the BIOWIN models for predicting biodegradability from chemical structure (part of the free Estimation Programs Interface (EPI) Suite) have played a prominent role in PMN review and identifying persistent, bioaccumulative, and toxic substances (PBTs). Recently, the BIOWIN models were validated using screening biodegradation data submitted for over 300 PMN substances that represent the extensive range of different molecular structures typical of commercial chemicals and a list of over 200 chemicals with either grab sample or field biodegradation half-life data . In the present work, the biodegradation modules of variety of commercially available software packages were evaluated using biodegradation data from these two sets of data. The predictive accuracy of each of the different models was compared and model-specific trends were identified using a structure-based assessment of the results. The results also provided insight into techniques that could be used to enhance the screening of the High Production Volume (HPV) chemicals and to assist in national programs aimed at identifying PBT chemicals.
Key words: biodegradation, chemical screening, QSARs, half-lives