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Environmental health databases on the World Wide Web.

A well-known development in computer systems is the collection of computer networks called "the Internet" (1). In recent months, a revolutionary service called the World Wide Web (WWW, or web) has become available on many other commercial systems after this article is published.

Readers of the Computer Corner may have noticed a lag from the last article to this latest one. The delay was deliberate in order to follow these recent developments, and it may be worth the wait. Using the criteria discussed in a previous article (2), World Wide Web fares extremely well as an information system. It is fast, has enormous depth, and is relatively inexpensive. Indeed, it is free for those who have Internet access at universities. Most of all, once you are familiar with this system, it is the easiest way to "surf the net."

There are excellent references already available on WWW (3), and some of the most useful are on the web itself. With that in mind, this article has three objectives: 1) to introduce the basics of web (including Internet connectivity, hypertext, and uniform resource locators), 2) to highlight environmental health databases on the web (more specifically, to invite NEHA members to access my personal WWW home pages, which accesses a range of environmental health information), and 3) to discuss possible applications of the web for the environmental health profession.

Internet Connectivity

The internet, as the name suggests, is an interconnection of computer networks. A key to understanding Internet is the level of connectivity. Connectivity refers to how users access an online database. For our purposes, there are three levels of Internet connectivity (with several variations within the three levels).

The first level is access through a so-called gateway. A gateway is a service that allows limited access to the Internet. Examples of this level include America On-Line (AOL), Prodigy, Compuserve, and other commercial services. This level has limited access to the tools of the Internet - for example, many will only have e-mail access. As mentioned earlier, this is changing, and e-mail can access much of Internet's tools.

Level two connectivity is a modern access to a "host computer." The host mainframe can execute a broad range of Internet commands, and your personal computer acts essentially as a terminal on that mainframe. For example, if you download a file, that file will go to the host (not to your personal computer). Level two is now the most commonly used level, and it is a standard for universities and large corporations.

Level three connectivity is direct access from a personal computer. It is the highest but also the most expensive level. However, there are various forms of level three activity. One variety uses a high speed modem operating on "Point to Point Protocol" (PPP) or "Serial Line Internet Protocol" (SLIP). Because this variation does not require 24-hour access normally associated with level three, it is far less expensive.


A key feature, called hypertext, makes World Wide Web easy to use. You move the cursor from one key term to the next on the screen. After pressing "enter" for a particular term, it automatically moves to information about that term. For example, if you select a highlighted word (usually by clicking on it with a mouse), the system then enters an entirely new document.

World Wide Web databases are all interconnected by hypertext. Literally, a world of information is available in a few keystrokes. Besides linking menus, keywords in documents are linked together. For example, you can read a document, find a keyword in that document that interests you, select that keyword (with a mouse), and arrive at a new document elsewhere in the world. Each new document has links with even more documents worldwide.

The web is accessed through something called a browser. A browser can read and fetch documents at multiple sites on the Internet. There are three basic types of web browsers: line-mode browsers, full screen browsers (e.g., Lynx), and graphical browsers (e.g., Mosaic or Netscape). Line-mode browsers are cheap but not very user-friendly. A full screen browser puts an entire text menu on the screen. Graphical browsers allow access not only to text, but also to pictures and sound. Most graphical browsers use a mouse, and you point-and-click on a highlighted link to access it.


In order to get started with all of the links mentioned earlier, it is essential to understand a feature called URLs, or Universal Resource Locators. URLs list the exact location of any Internet resource. Once you select a URL, it is possible to bounce from one link to another without ever knowing the exact address of that link. Here is an example of a URL:

The first part of a URL (before the colon) tells how to access that particular file. In this example, "http" stands for Hypertext Transport Protocol. The rest of a URL (after the colon) is the address of that particular file. In the above example, "" is the web address for my university ("www" stands for World Wide Web, "csun" stands for California State University at Northridge, and "edu" stands for educational institution). The remaining information lists my e-mail address (vchsc006) and the name of my WWW home page (tom.html).

The web also allows for keyword searches. An excellent web search engine is called the WebCrawler (located at the following URL: The WebCrawler searches not only the titles but also the content to match your keyword. Another well-known web search engine is called the World Wide Web Worm (located at the following URL:

When you find useful URLs, it is natural to want to save these for later use. This is accomplished with a feature called bookmarks. Bookmarks save the address of a menu or file so you can easily return to it at any time. All of your personal bookmarks are in a list that acts just like a personal menu.

Each Internet service has its own particular bookmark commands, but they all work on the same principle. First, you make a bookmark at a site that interests you. Second, you access that bookmark through a booklist that acts like a regular menu. For example, with Unix-based systems, there are four basic bookmark commands: "a" adds to your booklist the item that the arrow is pointing to; "A" adds to your booklist the current directory; "v" views your booklist at any time; and "d" deletes a bookmark from your booklist.

Environmental Health Databases on the Web

The specific web address mentioned in the previous section accesses a database labeled as the "CSUN Risk Communication Forum" (see Figure 1). This is called a home page, and as mentioned before, I invite all interested NEHA members to visit my home page. It includes a variety of databases relevant to environmental health, and it is all based on the use of hypertext. The easiest way to learn about these databases is actually to enter the web, but this section will briefly define these services.

Section A is a brief introduction to the Forum. Section B is a list of e-mail contacts (mostly elected officials). Section C has a set of Internet tools, including Gopher, Listserv addresses, Whitepages, and other services that can be discussed in later Journal issues.

Section D is a list of libraries and online periodicals. This includes the National Library of Medicine and the EPA library. Periodicals include EPA newsletters and journals, CDC's Morbidity and Mortality Weekly Report, and newsletters from the World Health Organization (WHO), and the Agency for International Development (AID). Section E includes information on my university department.

Section F includes various EPA links. This includes a keyword search, EPA regulations (air, water, waste, pesticides, toxics), freely available software, and other services. Section G is devoted to international agencies, including WHO, AID, and the United Nations environmental program. Section H and Section I are devoted to U.S. agencies, with an emphasis on the Department of Health and Human Services. Section J links various congressional sites, including the U.S. Senate, the U.S. House of Representatives, and access to the CFR.


The success of the web depends on an active network of environmental health professionals. All signs are that use of the web will grow at an unprecedented pace. Already, there are networks for physicists, chemists, biologists, and other scientists (7,8,9). Also, there are networks for environmental planners, physicians, and other professionals (10,11,12).

For our profession, the home page concept offers the possibilities for easy updating of various public documents. There are various possibilities for our university programs: 1) Faculty can more easily share course syllabi and lecture materials among universities; 2) Environmental health students, often excluded from NEHA annual meetings (due to costs for flight and hotels), can form useful networks at low or no cost; and 3) Continuing education can provide additional information through the web.

Agencies can use the web in at least the following ways: 1) Manuals can be easily updated and accessed by employees; 2) Regulations can be kept current by directly accessing the pertinent legal source (e.g., CFR); and 3) Agency newsletters on the web can expand outreach to the community.

For NEHA, these initial possibilities come to mind: 1) Basic information on NEHA services and membership information placed on the web could be accessed worldwide; 2) Committees within NEHA might accomplish much of their activities through the web; and 3) Mini-conferences could be sponsored on the web.

In future articles, more of these features will be discussed further. In the meantime, please try accessing my home page. I'll see you on the web!


1. Levine, J.R. and C. Baroudi (1993), The Internet for Dummies, IDG Books Worldwide, Inc., San Mateo, Calif.

2. Hatfield, T. (1994), "Computers and Environmental Health," J Environ Health, 57(3):33-34.

3. December, J. and N. Randall (1994), The World Wide Web Unleashed, SAMS Publishing, Indianapolis, Ind.

4. Walter, Russ (1993), The Secret Guide to Computers, Somerville, Mass. 02144.

5. Powell, J. (1995), "Spinning the World-Wide Web: An HTML Primer," Database, 18(1):54.

6. Kelly, B. (1994), "Becoming an information provide on the World Wide Web," Computer networks and isdn systems, 27(3):353.

7. Casher, O., G.K. Chandramohan, and B.J. Whitaker (1994), "Hyperactive molecules and the World-wide Web information system," J Chem Soc, (1):7.

8. Jacobson, D (1994), "The World Wide Web for Biologists," Protein Science, 3(11):2159.

9. Hardin, J.B., and B.R. Schatz (1994), "NCSA Mosaic and the World Wide Web: Global Hypermedia Protocols for the Internet," Science, 265(5174):895.

10. McKinney, P.W., J.M. Wagner, and L.M. Kirk (1995), "A Guide to Mosaic and the World Wide Web for Physicians," M.D. Computing: Computers in Medical Practice, 12(2):109.

11. Metcalfe, E.S., M.E. Frisse, and S.W. Hassan (1994), "Academic Networks: Mosaic and World Wide Web," Academic Medicine, 69(4):270.

12. Batty, M. (1994), "The World Wide Web," Environment and Planning, 21(6):651.

RELATED ARTICLE: Figure 1. CSUN Risk Communication Forum: (

A. Introduction B. e-mail contacts C. Internet tools D. Libraries/Periodicals E. CSUN Health Science Department F. EPA G. International agencies H. Cabinet agencies I. Other agencies K. Congress

Thomas H. Hatfield, Dr. P.H., R.E.H.S., Associate Professor, Dept. of Health Sciences, California State University, Northridge, CA 91330. Internet: THatfield@HUEY.CSUN.EDU.
COPYRIGHT 1995 National Environmental Health Association
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Article Details
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Author:Hatfield, Thomas H.
Publication:Journal of Environmental Health
Date:Jun 1, 1995
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