President Carter has asked the Justice Department to develop a model law states could pass to ban the manufacture and sale of drug paraphernalia, all the equipment used to prepare or use illegal drugs such as marijuana and cocaine.

Lee Dogoloff of the White House domestic policy staff reported this yesterday to two citizen groups that charged marijuana smoking is severely harming thousands of children and adolescents.

The groups, Citizens for Informed Choices on Marijuana and the Coalition for concern about Marijuana Use in Youth, asked the president to take a wide range of actions to help curb marijuana use.

They said it is not the largely safe drug it was claimed to be a few years ago, that younger and younger boys and girls are using it and that many are being damaged physically and mentally.

An increasing number of scientists and federal drug officials have begun to agree that marijuana can do severe harm.

Dr. Carleton Turner, director of a federal marijuana project at the University of Mississippi, Dr. Harold Voth, a psychiatrist at the Topeka, Kan., Veterans' Hospital and the Menninger Foundation, and other speakers told the two citizens groups:

Most of the current popular thinking about marijuana was developed when it was generally far less potent than much marijuana sold today, and marijuana's defenders envisioned its use by adults smoking it occasionally.

Use is becoming increasingly common in high schools and junior high schools, with many students getting stoned before school starts and staying that way.

The effects are often devastating, Voth said, and can include loss of memory and judgment, deterioration of personality and inability to learn, as well as damage to the lungs, sex organs and other parts of the body.

"Drugs and drug paraphernalia are common in our neighborhood," said Joyce Nalepka of Silver Spring, coordinator of the Coalition for Concern."And children as young as 8 or 9 begin using drugs now."

The two groups called on the president to broaden antidrug education and take measures to help parents. They asked him to help deal with the problem of the prevalence of drug-making and drug-using equipment.

In response, Dogoloff said the president has asked the Justice Department and Drug Enforcement Administration to develop a model law that many "interested" states and localities might use to prevent manufacture, advertisement or sale of a wide array of equipment.

"We've already been hearing from the paraphernalia manufacturers," Dogoloff said. "They're concerned. But we think this legislation could withstand the expected constitutional challenges, if some states and local units want to consider it."

Drug paraphernalia, as defined by the Justice Department, could include pipes, papers, spoons and syringes used to smoke, inhale or inject drugs, as well as equipment used to grow, manufacture, package and prepare them.