ctxR: Utilities for interacting with the CTX APIs

A new R package, ctxR, is presented. ctxR is an open-source R Client package used to interact with the Computational Toxicology and Exposure Application Programming Interfaces (CTX APIs) in R . The CTX APIs were developed by the US EPA’s Center for Computational Toxicology and Exposure, and provide users transparent, reproducible access in a programmatic manner to the data surfaced on the CompTox Chemicals Dashboard (CCD) and other data sources. The utility of this package is demonstrated through a case study that compares traditional Points of Departure (PODs) and PODs based on New Approach Methods (NAMs), referred to as PODNAM, relative to estimates of external exposure as an indicator of level of risk. This analysis combines a wide variety of data and showcases the power of programmatic data access that ctxR can provide to the scientific community. • ctxR is an R package to access US EPA chemical databases via APIs. • Accessible data include chemistry, hazard, in vitro bioactivity, exposure, and more. • ctxR provides transparent, reproducible, programmatic access to chemical data. • ctxR integrates chemical data queries into automated R-based analysis workflows. • ctxR is demonstrated with a NAM-based chemical prioritization case study.