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High-Throughput Toxicokinetics R Package Version 2.3.0

Published February 21, 2023

Toxicokinetics describes the rate a substance will enter the body and what occurs to excrete and metabolize the substance in a biological system following exposure. Toxicokinetics links external exposure concentration to the internal dose (i.e., the concentration of a substance in one or more systems of interest) and determines what occurs to the substance within the system. EPA researchers develop models to help estimate the amount of a chemical in the body which could lead to an effect. These estimates, along with exposure and hazard data, help inform predictions about chemical risks facing the public. The high-throughput toxicokinetics (httk) R package allows users to determine where chemicals go in the body much faster than traditional methods.

EPA researchers recently released a software update to the httk R package with new data and models that can be used to estimate chemical concentrations in humans. The package currently uses human in vitro data to make predictions about the fate of chemicals in humans, rats, mice, dogs, and rabbits.

The httk R package, v2.3.0 incorporates new in vitro measures of gut absorption for over 400 chemicals, new Quantitative Structure Property Relationship (QSPR) predictions, and many other refinements. See the full release notes on the httk R Package webpage.

If you have any feedback on this release that could be used for future improvements, please contact the Center for Computational Toxicology and Exposure (CCTE@epa.gov).

EPA scientists will continue to improve the accuracy of the HTTK R Package. New models are in development to describe absorption through the skin, exposure to aerosols (clouds of droplets), partial oral absorption, and human pregnancy. 

Access the package: httk: High-Throughput Toxicokinetics R Package   

Learn more about toxicokinetics:

  • Toxicokinetics: How Does the Body Process a Chemical?
  • High-Throughput Toxicokinetics (httk) R Package
  • Understanding Chemical Hazards in Occupational Settings: EPA’s HTTK R Package Update

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Last updated on February 4, 2025
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