General fugacity-based model to predict the environmental fate of multiple chemical species

Thomas M. Cahill, Ian Cousins, Donald Mackay

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


A general multimedia environmental fate model is presented that is capable of simulating the fate of up to four interconverting chemical species. It is an extension of the existing equilibrium criterion (EQC) fugacity model, which is limited to single-species assessments. It is suggested that multispecies chemical assessments are warranted when a degradation product of a released chemical is either more toxic or more persistent than the parent chemical or where there is cycling between species, as occurs with association, disassociation, or ionization. The model is illustratively applied to three chemicals, namely chlorpyrifos, pentachlorophenol, and perfluorooctane sulfonate, for which multispecies assessments are advisable. The model results compare favorably with field data for chlorpyrifos and pentachlorophenol, while the perfluorooctane sulfonate simulation is more speculative due to uncertainty in input parameters and the paucity of field data to validate the predictions. The model thus provides a tool for assessing the environmental fate and behavior of a group of chemicals that hitherto have not been addressed by evaluative models such as EQC.

Original languageEnglish (US)
Pages (from-to)483-493
Number of pages11
JournalEnvironmental Toxicology and Chemistry
Issue number3
StatePublished - Mar 1 2003
Externally publishedYes


  • Chlorpyrifos
  • Environmental fate
  • Multispecies model
  • Pentachlorophenol
  • Perfluorooctane sulfonate

ASJC Scopus subject areas

  • Environmental Chemistry
  • Health, Toxicology and Mutagenesis


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