“CTD is an effort to compile and organize increasingly copious amounts of formal research on the relationship between chemicals, genes and disease. The database is an attempt to map the complex ways in which chemicals are related to diseases.” Searches can be done by chemical, disease or gene. CTD is a database in the U.S. National Library of Medicine’s TOXNET family. Access it from our Toxicology/Occupational Health Resources and Indexes and Databases web pages.