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FGETS: Food and Gill Exchange of Toxic Substances

FGETS is a simulation program that predicts temporal dynamics of a fish's whole body concentration (µg chemical /(grams live weight fish)) of non-ionic, non-metabolized, organic chemicals that are bioaccumulated from water and food.
The model is based on a set of diffusion and forced convection partial differential equations, coupled to a process-based fish growth formulation.
Chemical exchange rates are estimated using fundamental principles of passive diffusion and thermodynamics rather than phenomenological toxicokinetic data.

FETS can be used to analyze the bioaccumulation of organic chemicals under laboratory or field conditions, and its predictions have been shown to agree well with both types of data.
For laboratory applications, FGETS can be used to model either constant flow or static exposures. For field assessments, FGETS can be used to simulate the chemical bioaccumulation in multiple fish species that are exposed to either constant or time-varying water concentrations and that feed on either single or multiple food resources.
For such assessments, FGETS can be configured to predict the dietary accumulation of chemicals in fish that feed on

  1. multiple fish species
  2. plankton/drift organisms
  3. benthos.

The model considers both biological attributes of the fish and physico-chemical properties of the chemical that determine diffusive exchange across gill membranes and intestinal mucosa. Important biological characteristics used by the model include the fish's gill morphometry, body weight, and fractional aqueous, lipid, and structural organic composition. Relevant physico-chemical properties are the chemical's aqueous diffusivity, molar volume, and n-octanol/water partition coefficient (Kow)).
The model is parameterized for a particular fish species by means of a morphological, physiological, and trophic database that delineates the fish's gill morphometry, feeding and metabolic demands, and body composition.

FGETS also calculates the time to reach a lethal activity in the fish assuming that the chemical has a narcotic mode of action.


area: dynamics of natural ecosystems
objectives: simulation, analysis
description: fishes, acquatic ecosystems, bioaccumulation, ecotoxicology, partial differential equations


The program is available at:
Center for Exposure Assessment Modeling (CEAM)
U.S. Environmental Protection Agency
Office of Research and Development
Environmental Research Laboratory
960 College Station Road
Athens, Georgia 30605-2720
Tel. 706/546-3549
The software ca be downloaded at the EPA-CEAM FGETS page


  • "GETS, A Simulation Model For Dynamic Bioaccumulation of Nonpolar Organics by Gill Exchange: A User's Guide" (EPA 600/3- 86-057) NTIS Accession Number: PB87 132 791. Cost $ 34.00
  • "FGETS, A Simulation Model for Predicting Bioaccumulation of Nonpolar Organic Pollutants by Fish". (EPA 600/3-87-038). NTIS Accession Number PB88 133 558. Cost $ 34.00



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