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Most Frequently Asked Questions about
Toxicology
Toxicology is the study of the adverse effects of substances on living things. From a brief summary of the toxicity of a given substance, to comprehensive literature search in support of a regulatory submission, the DIALOG® service can provide your answers.
Where do I start?
A. Start with the name of the toxic substance. This may include trade names, synonyms, and a Chemical Abstracts Service (CAS®) Registry Number, unique to that substance.
- If you have a list of substances, divide them into "rare" and "common or highly toxic." This will determine your search path as much as any other factor. A good test is to SELECT the name of the substance in TOXLINE® (File 156), and look at the number of records. You may get only a few because the substance is rare or because it is generally non-toxic or because the name you are using is not the commonest name for the substance.
- If you are looking for a few good records on a common toxin, look for your substance name in the Title (/TI) field in TOXLINE (File 156), e.g., SELECT BENZENE/TI. TYPE out the titles in Format 6, and look for an overview article. You may then want to search CHEMTOX® (File 337). First see HELP RATES 337, then EXPAND NA=<substance name> and TYPE the record in Format 2. The record will include regulatory data and test results, and a readable summary of the toxicity.
- Health & Wellness DatabaseSM (File 149) is another good place to look for overview articles, and many of them are full-text in this file (SELECT S1/FULLTEXT). File 149 is especially good for adverse effects of vitamins, minerals, herbal remedies, medications, folk medicines, and poisonous plants.
- The Registry of Toxic Effects of Chemical Substances (RTECS®) (File 336) is another basic toxicology reference file, and will help you to understand the references in the RTECS portion of the CHEMTOX record.
- If your substance is used in agriculture, there is an excellent characterization of these substances in Pesticide Fact File (File 306). BEGIN 306, EXPAND CN=<substance name>, and TYPE out the one record for the chemical.
- Hazardous Substances Databank (DataStar HSDB) is available on DataStar. Like CHEMTOX, there is a long record with regulatory data, but a very readable Toxicity field. Call 800-334-2564 for information on how to access and search DataStar.
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How do I perform a very comprehensive search? Or, I only got a few records; how do I expand my search?
A. Start in EMBASE (File 73). EXPAND your substance, in parentheses, e.g., EXPAND (BENZENE), to get into the thesaurus. Capture the display of names and numbers associated with your substance.
- Then BEGIN CHEMNAME® (File 398) (first see HELP RATES 398), and EXPAND NA=<substance name>. SELECT an entry, usually E3, from the EXPAND screen and TYPE out the resulting set to see the CAS Registry Numbers and synonyms for the substance. Then enter MAP SYRN TEMP. This will form a TEMPorarily SAVEd search to EXECUTE in the literature files. If you plan to LOGOFF here, write down the SAVEd search serial number, e.g., TA001, for use later.
- Now BEGIN the literature files that relate to your search. For example, from the chart, you might choose CANCERLIT (File 159)
for mutagens. Enter EXECUTE STEPS TA001 (or EXS
TA001) in the files to form a set.
- Compare the names for the substance which you got from EMBASE, and SELECT any that are not in the MAP from CHEMNAME, using the OR operator to form a final set containing all the substance names.
- Be sure to include TOXLINE (File 156), but only
File 156 assumes the toxicology concept
in the whole file. Enter SELECT S1 FROM 156
to form your second set, SELECT S1 AND (TOXIC?
OR TOXIN? OR POISON? OR HAZARD? OR ADVERSE OR SAFETY
OR SAFE) as your third set, and SELECT S2 OR S3.
Again, these set numbers may be higher if your
EXS formed more than one set.
- Then REMOVE DUPLICATES (RD). There are many duplicates within TOXLINE itself, as a result of the many subfiles from which it is constructed. The RD algorithm will keep the record with the highest accession number, not necessarily the one with a long abstract, so that is one last place to look of you have not yet found a readable summary of the toxicity of your substance.
- The TOXICOL, SAFETY, ENVIRON, and POLLUT categories are also available, for searching in both DIALINDEX® (File 411) and as a OneSearch® category. You may find more articles on a rare substance by searching these groups of files. Apply the "toxic" synonyms after you actually BEGIN the files, to save time in DIALINDEX.
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Are all the toxicology files literature files?
A. No, several are online "handbooks" or lists, with one substance per record. Registry of Toxic Effects of Chemical Substances (RTECS) (File 336), CHEMTOX (File 337), SEDBASE: Side Effects of Drugs (File 70), and TSCA (Toxic Substances Control Act) CHEMICAL SUBSTANCES INVENTORY (File 52) are files of this type. Pesticide Fact File (File 306) and Hazardous Substances Databank (DataStar HSDB) are discussed in the first answer, above.
- EXPAND NA= (for Name in Files 336 and 70) or CN= (for Chemical Name in Files 52 and 337) and the common name of your substance, and SELECT the basic record.
- Note that the TSCA Inventory gives only brief listings for chemical substances manufactured, imported, or processed for commercial purposes in the United States, and those substances are not toxic.
- SEDBASE is a listing of adverse effects of drugs, and refers you to EMBASE (File 73) literature.
- There is a Reference Guide to RTECS, and even if you are a toxicologist, you may need the Guide to interpret the records. To see the abbreviations in the data fields spelled out, use Format 9. Do not be surprised to see studies from older decades cited as proof of toxicity, teratogenicity, etc. Many of them are difficult to retrieve for the reason that they are older or non-English articles, but if a substance has been known as a toxin for many years, the original study is still cited.
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How do I know if this substance is safe to eat?
A. The Food & Drug Administration (FDA) does declare some substances as being "generally regarded as safe." They announce these rulings in the Federal Register (File 180), but there is no reliable terminology to select only those records, and no list online. Contact the FDA at 1-202-898-2343 or 1-800-733-1131.
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