The drug abuse and AIDS crises are claiming some new victims -- thousands of charitable health and service groups that have to compete with the two issues to get their own public service messages on the air.

To reach the public, the Advertising Council, government health agencies and marketers are refining their marketing techniques, increasingly relying on targeted market research, local promotions and creative distribution methods.

"People are moving to other forms for giving their messages," said Bob Druckenmiller, executive vice president of the public relations firm Porter/Novelli of Washington. "Some people are getting less of a share" of free network time.

"We're beginning to realize that if you use several media, the sum of the parts together is greater than the sum of the parts themselves," said Dan Langdon, senior vice president of public relations for the Advertising Council. "It is a growing trend."

The new approaches reflect a general evolution in thinking about public service advertising, advertisers and charities say. The usefulness of traditional, 30-second spots has been reevaluated as dwindling free network time and more complex issues propel advertisers to explore new media and public relations tools.

That exploration has been hastened by the rise of AIDS and drug abuse on the national agenda. While no exact figures are available, the National Association of Broadcasters estimates that the three commercial networks in 1988 donated more than $1 billion worth of television time for substance abuse ads alone.

By comparison, the Advertising Council, a clearinghouse for public service advertising, last year placed about $1.1 billion of donated time for more than 30 campaigns.

"We devote a significant amount of time to the Media Partnership for a Drug-Free America coverage," said William G. Clotworthy, director of program standards and public service at NBC. "It does make it difficult for the others."

To complicate matters, broadcast industry deregulation has freed local stations from having to air many national public service campaigns. Given the choice between airing a free announcement and a paid local spot, said one television industry source, "stations go with the paid commercial."

All the while, more organizations have appeared to crowd the field. "A lot of causes are crying out for attention," said Matthew Margo, vice president for programs and practices at CBS. "Not every issue or organization is necessarily going to be accommodated."

To compensate, charities and health groups are searching for alternatives. A key difference appears to be one of sophistication. Many public service advertisers are borrowing commercial and political marketing techniques.

"The more sophisticated organizations are doing more research, are making more efforts to work with local stations and have local promotions that tie into national efforts," said Harvey C. Dzodin, vice president of commercial clearance with ABC.

The National Heart, Lung and Blood Institute at Bethesda, for instance, this month began marketing a 15-minute video health quiz it produced to hundreds of local stations across the country.

The free tapes come with handbooks to help local broadcasters produce a 30-minute package they can promote and air themselves, said John C. McGrath, chief of communications and marketing for the institute.

In a nursing recruitment program sponsored by the University of Texas, agencies are mailing information kits to local high schools and contacting local stations and health officials for their endorsement, in addition to airing a national campaign with actress Dana Delaney, who plays nurse Colleen McMurphy on the ABC series "China Beach."

In another effort, the Advertising Council has contacted television script writers to include anti-alcohol-abuse messages for young people in prime-time programming. The change reflects public service groups' sense that they must refine their messages to appeal to target groups, said McGrath. In the National Heart, Lung and Blood Institute's work with blood pressure and cholesterol-level-awareness programs, McGrath said, it tries to hone its message yearly, adjusting to public knowledge and national trends.

New options also are becoming available, particularly with cable TV. The amount of donated time on cable has risen 10 percent annually the last three years to $95 million in 1989, according to the Cable Television Advertising Bureau.

"The old mechanism used to be, you took on a campaign and there were some 22,000 media outlets and everything went to everywhere. That's not a terribly efficient way of doing things," Landon said. "There's simply more media available."