The EFDB aids in identifying persistent chemical classes, as well as physical or chemical properties that may correlate to particular behavior in the environment. The EFDB is comprised of several interrelated files, including DATALOG, CHEMFATE, BIOLOG, and BIODEG. These databases share a CAS# file containing over 20,000 chemicals with a preferred name and formula, and a bibliographic file containing full references on over 36,000 articles cited. They are under constant expansion, and may be accessed on the EFDB webpage. Quarterly, snapshots of the databases are made available in a Microsoft Windows version and on this web site.