American teenagers generally have a better relationship with their mothers than their fathers--a relative lack of paternal involvement that is key in determining whether teenagers begin to use drugs, according to a new national survey that was released yesterday.

The survey, which was commissioned by the National Center on Addiction and Substance Abuse (CASA) at Columbia University, found that teenagers in two-parent households who have only a poor or fair relationship with their fathers are at about 60 percent more risk of abusing drugs than a teenager living with a single mother who has an excellent relationship with the youth.

According to the survey, 71 percent of teenagers described their relationship with their mothers as excellent or very good, but only 58 percent said they have such a relationship with their fathers. By large margins, they also said it was easier to talk to their mother than their father about drugs, and that they were more likely to rely solely on their mother than their father in making important decisions.

Forty-five percent of the teenagers said their mother was the more demanding parent when it came to school grades, homework and personal behavior, compared with 39 percent who said the father was the more demanding, the survey found.

"Many dads are AWOL in the battle against substance abuse and this greatly increases the risk that their children will smoke, drink and use illegal drugs," said Joseph A. Califano Jr., president of CASA.

The survey, conducted by pollster Frank Luntz, was based on telephone interviews in May and June with 2,000 young people ages 12 to 17 and 1,000 parents. Each teenager was assigned a drug abuse risk factor based on their answers to such questions as whether they have friends who drink or use illegal drugs and how long it would take for them to buy marijuana. The risk factors were then correlated with other data in the survey such as relationships with parents.

"It is really stunning the extent to which we can predict the risk score if we know about the teen's home life," said Steven Wagner, president of QEV Analytics, a public opinion research firm that analyzed the data. "The quality of the relationship with both parents is very important to risk. We focused on fathers because a bad relationship with fathers is so much more common than with mothers. If mothers did the same thing it would be equally harmful, but it's much rarer for moms to be absent or distant."

At a news conference to announce the survey results, Califano, who was secretary of health, education and welfare in the Carter administration, said that teenagers in two-parent families who have good relationships with both parents are at the least risk of having drug abuse problems. But he said absent fathers or those who are not engaged in the lives of their teenage children "is a really serious problem and one that we can correct."

"We can't leave it up to mom," he added. "She's doing a terrific job, but she can't do it alone."

According to the survey, the risk of substance abuse by a student who attends a school where drugs are available is twice that of students who attend drug-free schools. Older teenagers are less likely than younger teenagers to report drug activity at their schools--82 percent of 12-year-olds said they would report a drug dealer to school officials, but only 37 percent of 17-year-olds said they would do the same.

The survey, the fifth conducted by CASA, detected some encouraging trends, Califano said. It showed that 60 percent of teenagers do not expect to use a drug in the future, compared with 51 percent last year; 44 percent said they attend a drug-free school, up from 31 percent in 1998, and 40 percent said the drug situation at their school is getting worse, compared with 55 percent in 1998.