Washington ? Risky teen behaviors such as smoking tobacco or marijuana, not wearing seat belts and having sex neared or reached record lows last year, the Centers for Disease Control and Prevention reported Wednesday.

“We are pleased that more high school students today are doing things that will help them stay healthy and avoiding things that put their health in danger,” said Howell Wechsler, the director of the CDC’s adolescent and school health division.

The survey of 14,000 ninth- to 12th-graders, which the CDC has conducted every other year since 1991, showed sharp differences among blacks, whites and Hispanics, however.

This was especially true about sex.

For blacks, the percentage who’d ever had sex dropped from 72 percent in 1991 to 66 percent in 2007. For whites, it dropped from 50 percent to 44. But for Hispanics, it dropped just 1 percentage point, from 53 percent to 52.

The same held for sex with four or more partners. Black high schoolers dropped from 43 percent to 28. Whites fell from 15 percent to 12. But Hispanics remained at 17 percent.

Hispanics were also more likely than black or white students to attempt suicide, use cocaine, heroin or ecstasy, and to go 24 hours or more without eating in order to lose weight.

Sonia Perez, the senior vice president of the National Council of La Raza, a nonprofit agency that advocates for Latino issues, blamed their relative poverty.

“When Latino teenagers live in poor households, have less-educated parents and go to overcrowded schools that offer less-quality education, it is more likely that they will engage in these kinds of behaviors,” she said.

However, black teens also have a higher rate of poverty than whites.

Wechsler, who urged educators to focus more attention on Hispanic students’ risk-taking, noted that Hispanic teens had improved in two areas: less drinking and more condom use.

Not enough Native Americans or Asian-Americans took part to allow separate comparisons for those groups.

For ninth- to 12th-graders overall, there were lots of lifestyle improvements. Among them:

¢ Smoking in the 30 days before the survey fell from a peak of 37 percent in 1997 to 20 percent last year.

¢ Drinking in those 30 days fell from 51 percent in 1991 to 45 percent last year.

¢ Marijuana use in the previous month dropped from a peak of 27 percent in 1999 to 20 percent.

¢ Riding in that period with a driver who’d been drinking dropped from 40 percent in 1991 to 30 last year.

“Nationally, experts are reporting similar data: The rates of risky behaviors such as smoking, drug use and sexual intercourse have decreased,” said Vaughn Rickert, an adolescent health expert from Columbia University.

He said the improvements might be due to greater news coverage of risky behaviors, more use of the Internet by teens seeking information about them and more effective prevention programs in schools.

According to the report, 72 percent of all deaths in the larger 10-to-24 age group were due to four causes: car crashes, unintentional injuries, homicide and suicide.

“We still have a long way to go,” Wechsler said.