The Comparative Toxicogenomics Database^TM (CTD: ctd.mdibl.org) is a public, web-accessible database designed and curated to promote understanding about the effects of environmental chemicals on human health.

Most human diseases involve interactions between genetic and environmental factors. 85,000 chemicals are listed in the US Environmental Protection Agency Toxic Substances Control Act Chemical Substances Inventory, but the molecular mechanisms underlying the actions of many of these chemicals are still poorly understood.

CTD identifies gene-chemical interactions in diverse species and facilitates cross-species comparative studies of these genes. These comparisons help identify functionally conserved sequences, provide insight into their function and role in modulating chemical actions, and improve understanding about the genetic basis of variable susceptibility to environmental chemicals.

CTD provides pre-generated multiple sequence alignments (left) and phylogenetic trees (not shown) using cDNA and amino acid sequences from curated sets of toxicologically important genes and proteins ("Gene Sets"). These visualizations help researchers evaluate relationships and determine similarity between evolutionarily related sequences.