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Fact Sheet
Comparative Toxicogenomics Database (CTD)™

The Comparative Toxicogenomics Database (CTD) elucidates molecular mechanisms by which environmental chemicals affect human disease. CTD is a data file on the National Library of Medicine's (NLM) Toxicology Data Network (TOXNET®). It contains manually curated data describing cross-species chemical–gene/protein interactions and chemical– and gene–disease relationships. The results provide insight into the molecular mechanisms underlying variable susceptibility and environmentally influenced diseases. These data will also provide insights into complex chemical–gene and protein interaction networks.

CTD is developed at North Carolina State University (NCSU)  The development team is located at NCSU and the Mount Desert Island Biological Laboratory (MDIBL) CTD receives funding from the National Institute of Environmental Health Sciences (NIEHS) and the National Library of Medicine (NLM) by the R01 ES014065 "Comparative Toxicogenomics Database" grant, as well as through an administrative supplement (R01 ES014065-04S1) and another R01 (R01 ES019604), "Generation of a centralized and integrated resource for exposure data," from the NIEHS.

Web Access/Searching

CTD is accessible, free of charge, via TOXNET at:

In TOXNET, users can search chemicals (by name or CAS registry number) and see the related genes and diseases. Users can then be taken via the TOXNET’s CTD results to the complete CTD site for further details.

Once in the complete CTD site via TOXNET, users can perform several types of searches, for example:

  • Browse relationships among chemicals, and obtain detailed information about them, including structure, toxicology data and related genes, diseases, pathways and references. See: Chemicals
  • Browse relationships among diseases, and obtain detailed information about them, including related chemicals, genes, pathways and references. See: Diseases
  • Browse search for genes from diverse vertebrates and invertebrates by symbol, synonym, accession ID, organism taxon, chemical, interaction type, disease or Gene Ontology annotation. See: Genes
  • Search for cross-species chemical–gene and protein interactions curated from the published literature. Interactions may be retrieved by chemical, interaction type, gene, organism or Gene Ontology annotation. See: Chemical–Gene Interactions
  • Search for references by gene, organism taxon, chemical, chemical–gene interaction type, disease, citation information or accession ID. See: References

Further examples of searches that can be conducted once users are in the complete CTD site via TOXNET include:

Users can also easily conduct their CTD search strategy against other databases, e.g., Hazardous Substances Data Bank®, TOXLINE®, and ChemIDplus®.

Further Information

For detailed information about CTD or TOXNET, contact:

CTD Representative
Specialized Information Services
National Library of Medicine
Two Democracy Plaza, Suite 510
6707 Democracy Boulevard, MSC 5467
Bethesda, MD 20892-5467
Telephone (30l) 496-1131
FAX: (301) 480-3537

For comments on CTD content, contact:

Comparative Toxicogenomics Database
Mount Desert Island Biological Laboratory
P.O. Box 35, Old Bar Harbor Road
Salisbury Cove, ME 04672, USA
Phone: 207-288-9880 ext. 283
e-mail: Go to

For information on NLM services, contact:

National Library of Medicine
Customer Service
8600 Rockville Pike
Bethesda, MD 20894
Telephone: 1-888-FINDNLM (1-888-346-3656) or (301) 594-5983

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Office of Communications and Public Liaison
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Phone: (301) 496-6308
Fax: (301) 496-4450