übertool: web applications for ecological risk assessment (beta version)
Cloud-based environmental models used by the USEPA for evaluating pesticide risks to ecosystems under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Endangered Species Act (ESA).
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T-Rex Overview

This spreadsheet-based model calculates the residues on avian and mammalian food items (e.g., short or tall grass, seeds, insects, etc) along with the dissipation rate of a chemical applied to foliar surfaces (for single or multiple applications) in order to estimate acute and reproductive risk quotients. T-REX offers two unique advantages over similar models: 1) the relative body weight of the animal under assessment, as compared to the test animal, is used to adjust acute and chronic toxicity values and 2) risk quotients are calculated for granular applications and seed treatments. Output for both avian and mammalian diet- and dose-based EEC and RQs are based on upper bound and mean Kenaga values.


T-REX users enter specified endpoint data obtained from avian or mammal acute oral LD50, acute dietary LC50, or reproductive NOAEC/L toxicity studies to calculate risk quotients. Users must also choose a test species from a drop-down menu. For avian models, bobwhite quail and mallard duck data is commonly used. If the body weight of a different test species is known, the user can choose “other” from the drop-down menu. For mammalian models, the “other” option is not currently available, therefore, test species other than laboratory rats must be done by hand.


Estimates of LD50 ft-2 risk index values can be generated in T-REX for granular formations and row, banded and in-furrow applications. An adjusted LD50 toxicity value and EEC are used for the LD50 ft-2 calculation which is then compared to a specific Agency’s level of concern (LOC).