GUTS_IT: GUTS-IT scenario

In cvasi: Calibration, Validation, and Simulation of TKTD Models

GUTS-IT scenario

Description

Full General Unified Threshold models of Survival (GUTS) with Individual Tolerance compatible with the Full GUTS model as described by EFSA (2018), but some parameter names may differ.

Usage

GUTS_IT(scaled_ci = FALSE, dose_metric = c("D", "Ci", "Cw"))

Arguments

scaled_ci	logical, switch to enable scaling. If TRUE, the model will use the scaled internal concentration ⁠Ci*⁠. Else no scaling. Default value is FALSE.
dose_metric	character, selects the dose metric. 'D' to use damage, 'Ci' to for internal concentration, or 'Cw' for the external concentration. Default value is 'D'.

Value

an S4 object of type GutsIt-class

State variables

The following list describes the default names and standard units of GUTS state variables:

• Ci, (scaled) internal concentration (conc)

• D, (scaled) damage (*)

• H, cumulative hazard (-)

The state variables are initialized with zero by default.

IT model parameters

The set of parameters and their names follows the definition by Jager et al (2011). The actual number of required parameters depends on the selected model variant, i.e. if the internal concentration is scaled or not, as well as the selected dose metric. The full set of parameters is as follows

• ki, accumulation rate into body (time^-1)

• ke, elimination rate (time^-1)

• Kiw, scaling constant for external concentration (*)

• kr, damage recovery rate (time^-1)

• hb, background hazard rate (time^-1)

• alpha, median of thresholds (conc)

• beta, shape parameter (-)

Effects

The effect endpoint L (lethality) is available for GUTS models. A value of zero (0.0) denotes no effect on organism survival. A value of one (1.0) denotes a lethality rate of 100%, i.e. no survivors.

The survival probability S is available in the return value of simulate().

References

EFSA PPR Panel (EFSA Panel on Plant Protection Products and their Residues), Ockleford C, Adriaanse P, Berny P, et al., 2018: Scientific Opinion on the state of the art of Toxicokinetic/Toxicodynamic (TKTD) effect models for regulatory risk assessment of pesticides for aquatic organisms. EFSA Journal 2018; 16(8):5377, 188 pp. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.2903/j.efsa.2018.5377")}

Jager T., Albert C., Preuss T.G., and Ashauer R., 2011: General Unified Threshold Model of Survival - a Toxicokinetic-Toxicodynamic Framework for Ecotoxicology. Environ. Sci. Technol. 45(7), pp. 2529-2540. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1021/es103092a")}

See Also

GUTS-RED-IT

Other GUTS models: GUTS_SD()

cvasi documentation built on Sept. 11, 2025, 5:11 p.m.