Performance of on-line chemical property estimation methods with TSCA premanufacture notice chemicals.

CHEMEST is an interactive on-line system for estimating chemical properties important in environmental fate assessment. In 1988 we described an extensive validation study of CHEMEST. That study showed that for existing chemicals, most properties could be estimated with accuracy sufficient for screening-level assessment. Reported here are the results of a study of system performance with "new" chemicals, for which Premanufacture Notices (PMNs) must be submitted under the Toxic Substances Control Act. Measured values of key properties were retrieved for more than 300 PMN chemicals having discrete structures, which represented the majority of notices with submitted data that were received by the U.S. Environmental Protection Agency during the period 1979-1990. The measured values were compared to estimates from AUTOCHEM, an automated version of CHEMEST. Errors were generally greater than those for existing chemicals, as expected. Water solubility and the octanol/water partition coefficient (Kow) were estimated with acceptable accuracy, but the results for melting point and boiling point indicate that additional effort is needed to improve the estimation methods.