long empty needs.�
These may be any combination of words, chemical names, and numbers,
including Chemical Abstracts Services (CAS) Registry Numbers (RN).� Common �stop words� such as �a,� �an,�
�for,� �the,� and �it,� although you may enter them, will not be searched.
Examples of search terms:
- vinyl chloride
- dna adducts
- skin tumors in mice
- aflatoxin b1
The term(s) entered will be searched for in all IRIS fields.
The search will be initiated
when you click the
� � button.� To erase your search terms and start with a blank box again, click on
the � �
If your query consists of
chemicals, TOXNET will, by default (i.e.,the radio button �Yes� is
marked) expand your search by adding synonyms and
CAS Registry Numbers.� Thus, if you
enter �perchloroethylene,� the system will add the RN 127-18-4 and synonyms such as tetrachloroethylene and tetrachloroethene.� You have the option to turn off this feature
by marking the button �No.�� This will result in a search only for the
exact word(s) you entered.� In the
example above, the system would then look only for the word
For typical queries, it is
suggested that you leave the synonym searching feature on (
leave Yes button marked) in order to maximize
retrieval.� On the other hand if you were searching
specifically for a brand name product, say �tylenol� and were interested only in records that
mentioned the chemical with that name, you might want to turn off synonym
searching ( mark No button). Th is feature display s
a segment of the IRIS index
beginning with the term you enterand let s
you scan the index alphabetically (or numerically) above or below the original
display by clicking on the �UP� or �DOWN� button.� The number of IRIS
records containing each of the term s is displayed.� By checking boxes next to the index terms of interest and clicking on the � Check to �
button, you can search on the se terms.�
You may browse the index to all words, CAS Registry Numbers, or chemical
Clicking on any of the cells
in this column will take you directly to the search screen for the database
listed.� �Multi-databases� offers simultaneous
searching of HSDB, CCRIS, IRIS, and GENE-TOX.�
The information icon (�i�) next to each database provides a brief
description of it, with links to a more detailed Fact Sheet and a sample
You may also visit additional NLM Web-Based Resources:
����������� DIRLINE � Directory
and health and scientific
����������� Tox Web Links � Links to
additonal toxicology web sites.
����������� MEDLINEplus Tox/Env
Health � Consumer health information on toxicology and environmental
����������� PubMed � Access to the MEDLINE database of biomedical literature.
����������� NLM Gateway � Searches across multiple NLM databases.
����������� Locatorplus � NLM�s online catalog of books, audiovisuals, and journals.
Or Support Pages:
����������� Help �
Page specific detailed documentation, such as what you are now reading, about searching
����������� Fact Sheet �
For an expanded description of IRIS.
����������� Sample Record � A look at a sample IRIS record.
����������� EPA Disclaimer � Brief EPA account of IRIS data, including links to further information.
Your initial retrieval is displayed as a list of chemical names, highlighted in blue and underlined, and their CAS Registry Numbers.� If your search was for a chemical and there is a match for it in the database, the record for this chemical, referred to as the primary chemical record (e.g., benzene), will display first, followed by a list of other chemical records which also contain some mention of the chemical you entered.� This latter list of chemicals is displayed according to a Relevancy Ranking algorithm.� Clicking directly on any of the items will provide a display of the Selected Record Screen, containing all the data, for that item.
If your query consists of words that are not chemical terms, this same Relevancy Ranking algorithm determines the order of display of all your search results.
By checking one or more of
the numbered boxes to the left of
each record, you can perform later operations such as downloading on these selections.
You can alter your search, if you choose, directly in the query box which reappears on this page with your search terms.� Alternately, you can use the Modify Search button, described below.
The top and bottom of each
Search Results page always displays the total number of items retrieved and the
range of items displayed on the current page, and, depending on the number of
search results, the current page number and the total number of pages. You can
navigate through multi-page search results either by specifying a page number
pushing the �Go�
button or by using the small
This screen displays the
record for whichever item you selected on the Search Results screen.� If you search for a chemical (e.g., benzene) and then click
on the �Primary Record� of the Search Results screen, you will see the entire
record, along with a Table of Contents frame on the left.� If you click on a different chemical record,
the sections of the record best matching your query terms will be displayed
(see Best Sections), again, with an accompanying Table of Contents
frame.� From the Table of Contents, you can then
select to view portions of the record by expanding and contracting categories
and selecting specific categories and/or fields of the record.
If your original search was for a term other than a chemical, any chemical record you click on from the Search Results screen will result in a �Best Sections� display.
The search term(s) you entered, as well as synonyms (if you selected to search for them) will all be highlighted in red wherever they appear in the text of the selected chemical record.
Across the top of the screen
buttons with more options:
TOXNET searches for your
terms, in singular and plural form, throughout
the records unless you specify
particular fields.� The system will
automatically look for synonyms and CAS Registry Numbers of chemicals unless
you choose to disable this feature.
you search on multiple
query terms, and each record retrieved
contains all the terms you entered, the system will first display those records
in which all the terms appear in the same section of the record.� This will be followed by records where the terms appear
an ywhere in
sectionsthe record.� If a multiple-term search fails to retrieve
any records containing all the terms entered, the system will display the
following message: �No records were found which contain all of the search
words.� The following records contain at
least one of the words.�
Relevancy ranking attempts to determine which documents are most pertinent to the search, and to place the most relevant documents first in the list of returned documents.� The ranking is based upon the number of individual search terms occurring in a document, the number of times each search term occurs in a document, its rarity within the database, and the nearness of search terms to each other.� Documents containing combinations of search wordstend to be ranked higher than documents having isolated occurrences of the words.
searching for a particular chemical, say benzene, your retrieval may include chemical records
of the initial matching chemical record,
called the �primary� record.� These other records might appear
if they otherwise
contain the word �benzene.��
This might occur, for example, if the chemical is a metabolite of
benzene, interacts with benzene, or has been tested along with benzene in a
Clicking on any of these non-primary chemicals on the Search Results screen will display the Best Sections, those where the chemical search term appears with greatest frequency.� The term searched appears highlighted in red.
where Best Sections would occur is in
searching for a subject, say �DNA.�� In
this case, clicking on any of the chemicals in the Search Results screen will
display the Best Sections, i.e. the sections of the records where the word
�DNA� appears with the greatest frequency.�
IRIS contains data in support of human health risk assessment.� It is compiled by the U.S. Environmental Protection Agency (EPA) and contains over 600 chemical records.� IRIS data, focusing on hazard identification and dose-response assessment, is reviewed by work groups of EPA scientists and represents EPA consensus.� Among the key data provided in IRIS are EPA carcinogen classifications, unit risks, slope factors, oral reference doses, and inhalation reference concentrations.
Users seeking a finer degree of precision in retrieval than available through TOXNET�s standard Basic Search screen may want to consider formulating searches through the use of Boolean logic.
Users seeking a finer degree
of precision in retrieval than available through TOXNET�s standard relevancy
ranking methodology may want to consider formulating searches through the use
TOXNET is best viewed with Internet Explorer 4.0 or Netscape 4.0 or higher versions, for either PC or Mac.