Comparative Toxicogenomics Database: update 2027

The Comparative Toxicogenomics Database (CTD; https://ctdbase.org) is a well-established public resource that aims to advance understanding about how environmental chemical exposures affect human health. By integrating expertly curated content from the scientific literature with functional and pathway associations, CTD empowers researchers to develop testable hypotheses about mechanisms underlying environmentally influenced diseases. Today, CTD includes over 110 million integrated toxicogenomic connections linking harmonized chemicals, genes/proteins, phenotypes, anatomical terms, diseases, comparative species, pathways, and human exposures. In this biennial update, we introduce several new enhancements, including a streamlined modern web interface; a new curation module that captures experimental chemical concentrations reported in toxicogenomic studies; an enhanced "CTD Tetramers" tool that ranks results using weighted evidence scores, transforms tetramers into illuminated chord diagrams, and provides filters to discriminate mechanistic from therapeutic datasets; an expanded "Batch Query" tool that now retrieves detailed human exposure data; and enhanced chemical querying and interoperability via the inclusion of external chemical identifiers. Together, these advances further strengthen CTD as a comprehensive resource for exploring molecular mechanisms linking environmental exposures and human disease and for generating testable hypotheses about chemical-disease-exposure relationships.