Journalist Morrow Mayo once commented that Los Angeles, with its quick embrace of quirky health fads, 'leads the world in the advancement and practice of all the healing sciences, except perhaps medicine and surgery.'

Much the same can be said of the Internet.

A bounty of health and medical information is available online -- more than 17 million Web pages have the word 'health' in them, according to the AltaVista search engine.

The difficulty is determining what's reliable and what's quackery, what's objective information and what's being promoted by a private company with a commercial interest.

In this column, I'll point you to some of the major government Internet sites that have authoritative statistical data on health care issues.

Next time, I'll review other Web pages you can use to locate doctors and hospitals, online medical reference works used by health practitioners, medical research journals and studies, and search engines for finding more health resources.

  Medical Data Online

The main federal government Web page for medical data is the National Center for Health Statistics, part of the Centers for Disease Control and Prevention.

At the NCHS site is a 'Data Warehouse' section with numerous reports and statistics on diseases, injuries, deaths and related health issues.

At that page you have various options for getting different types of health data. They include: Statistics on major health care topics in chart or graph form. To get those, click on the small arrow to the right of the words 'Statistical tables, charts, and graphs.' Then select a topic from the list.

Basic health statistics on very common subjects, such as the incidence of the common cold, the average length of a hospital stay, how often people visit the doctor or dentist, or how frequently common surgical procedures are performed. To get that information, in the box on the left click on the words 'Frequently Asked Questions.' You'll then see a list of health-related subjects.

Statistics on a broader range of health topics -- about 200 in all ? including links to state medical data. To get to those topics, in the box on the left click on 'FASTATS A to Z.'

Raw data on health issues in individual states that you can download onto your computer. To get to that information, click on one of the small arrows next to the topics listed under the words 'Healthy People 2000 -- State Data' (which is just under the general heading, 'Downloadable spreadsheet files'). From there you can access a series of files you can download using File Transfer Protocol and then open with any standard spreadsheet program. If you want to know what is in a particular document before you download it, click on the file nearest to it labeled 'readme.txt.' You also can search the entire NCHS site by keyword. To do that, in the box on the left of the Data Warehouse page, click on the words 'NCHS Web Search.'

A good site for tracking down other government health databases is the WONDER service of the Centers For Disease Control.

The WONDER site allows you to query two dozen different medical databases. They include statistics on sexually transmitted diseases, birth and mortality rates, injuries, tuberculosis, fluoridation, even population projections based on U.S. Census data. In addition, there are several databases of abstracts of CDC and other health publications.

To access the databases, at the WONDER page click on the 'anonymous user' button and then select 'Get Info.'

For international health statistics, check out the World Health Organization Web site at http://www.who.int.

For summary reports on various health issues, at the WHO home page click on the left on 'Health Topics.'

For statistical information on the incidence of different diseases, you can use WHOSIS -- the World Health Organization's Statistical Information System.

Included in the available documents is an online version of the annual World Health Report, which has detailed information on worldwide trends in diseases.

  Other Medical Databases

There are many more databases run by government agencies or universities that focus on particular diseases or specific aspects of health care.

For data on the AIDS epidemic, try the AIDS/HIV Resources page run by the Centers for Disease Control. At that page, to get statistical information on AIDS, on the left click on 'Resources by Topic' and then select the icon labeled 'Statistics/Trends.'

At the CDC site there's also a database of organizations involved in the fight against AIDS, including clinics, medical associations, public education organizations and support groups.

To get to that database, at the main AIDS/HIV Resources page click on the left on 'Databases' and then select 'Resources and Services.' At the next page, click on 'Search the Resources and Services Database.' At the screen that comes up you can type the name of a city into the search boxes to see what AIDS-related groups are operating there.

Another valuable site for AIDS data is the HIV InSite Web page at the University of California, San Francisco.

HIV InSite is a gateway to AIDS information on the Internet, and includes summaries of recent news stories and links to reports and statistical databases on AIDS.

For cancer statistics, the Public Health Institute in California operates the Ask C/NET online database, which has information on cancer incidence in the United States and in California. You can retrieve data based on the type of cancer, the age or race of patients, the type of treatment, etc.

The national data is drawn from SEER -- the Surveillance, Epidemiology, and End Results program of the National Cancer Institute. The California data comes from the Cancer Surveillance Section of the California Department of Health Services.

For information on physical and mental disabilities, West Virginia University's International Center for Disability Information has a Disability Tables Web page with statistical information culled from a variety of government sources. The tables, which include state, national and international data, are at http://web.icdi.wvu.edu/disability/tables.html.

For Medicare and general health care spending data, try the Health Care Financing Administration's Information Clearinghouse at http://www.hcfa.gov/stats/stats.htm.

For women's health care issues, The New York Times has put together a special Web page at http://www.nytimes.com/specials/women/data.

Using data from the Centers for Disease Control, The New York Times site compares the incidence of various illnesses for women with those for men, in a database that goes back to 1960.