Ch. 10— Information Resources and Computer Systems • 229 
try would provide baseline data within speci- 
fied time frames of measurement, and make 
it easy to check for the possibility of genetic 
drift. 
• New Perspectives on Old Data. By perform- 
ing statistical comparisons across data sets and 
identifying relationships not already obvious, 
unforeseen relations could be established 
without animal experimentation. 
The scientific community makes use of a num- 
ber of computerized literature retrieval services 
to obtain bibliographic citations and abstracts to 
the published literature. Most abstracting and in- 
dexing services started as publications, but most 
are now available on-line as well. Others, such as 
AGRICOLA , are only available on-line. 
Many handbooks and other numerical databases 
are also available on-line. Several numerical data- 
bases are sponsored by the Federal Government. 
The most comprehensive, the recently terminated 
Laboratory Animal Data Bank, is reviewed in de- 
tail in the next section. Two current systems, the 
Toxicology Data Bank and the Registry of Toxic 
Effects of Chemical Substances, are discussed in 
some detail here. Table 10-2 lists a number of data- 
bases available for searches of the research and 
testing literature. Table 10-3 lists some widely used 
databases of the NLM. 
Toxicology Data Bank 
The Toxicology Data Bank (TDB) was made public 
by NLM in 1978. It is designed to address some 
of the needs of the testing and regulatory com- 
munities for toxicity information. TDB is organized 
by individual chemicals or substances, now totaling 
more than 4,000. Its fixed format includes: 
• data on the production and use of each 
chemical; 
• a description of the physical properties of each 
chemical; and 
• the results of pharmacological and biochemi- 
cal experiments, and information on toxico- 
logical testing. 
TDB is based on conventional published sources 
and does not include unpublished data. Thus, base- 
line data on control animals, which might be used 
in place of a control group, could not be included 
because so little has been published. 
The most valuable feature of TDB is the fact that 
all the data it contains are peer-reviewed. As a con- 
sequence, its data summaries are acceptable to 
most users (5). (Another database containing only 
peer-reviewed data is the Environmental Protec- 
tion Agency's Gene-Tox.) 
Registry of Toxic Effects of 
Chemical Substances 
The Registry of Toxic Effects of Chemical Sub- 
stances (RTECS) has been published annually since 
1971 by the National Institute for Occupational 
Safety and Health, under Section 20(a)(6) of the 
Occupational Safety and Health Act of 1970 (Pub- 
lic Law 91-596). RTECS is a compendium, extracted 
from the scientific literature, of known toxic and 
biological effects of chemical substances. RTECS 
does not evaluate the data it cites, leaving that 
responsibility to the reader. An example of the in- 
formation contained in a typical substance entry 
in RTECS is given in figure 10-4. 
By congressional mandate, those data that indi- 
cate a toxic effect of a chemical are to be included 
in RTECS; those that show no toxicity are to be 
excluded. Thus, RTECS does not include negative 
results. Moreover, a chemical might not be in- 
cluded in the registry for a variety of reasons, in- 
cluding the following: 
• The test results could not be cited because 
the protocol of the study did not meet the 
RTECS selection criteria. 
• The substance has not yet been tested or the 
results have not yet been published. 
• The substance has been tested and the results 
published, but the information has not yet 
been entered into the RTECS file. 
The exclusion of negative results from RTECS and 
its incompleteness for these other reasons may 
lead to the repetition of toxicity testing of essen- 
tially nontoxic substances. 
The production of RTECS costs approximately 
$500,000 per year. The current quarterly update 
includes a total of 68,000 compounds, and it con- 
tinues to grow steadily toward the estimated 100,000 
unique substances for which toxicity data may be 
available. If RTECS were expanded to include all 
results of whole-animal toxicity testing, including 
