WASHINGTON >> Zero-tolerance policies are ineffective in combating bullying, an independent government advisory group says in urging schools to take a more preventative approach that includes teaching tolerance to address this “serious public health problem.”

In a report released Tuesday, the National Academies of Sciences, Engineering, and Medicine said bullying should no longer be dismissed as merely a matter of kids being kids. “Its prevalence perpetuates its normalization. But bullying is not a normal part of childhood,” the report said.

Schools, the researchers concluded, should end zero-tolerance policies that automatically suspend students for bullying.

“There’s no evidence that they are impactful in a positive way,” said Catherine Bradshaw, a professor and associate dean at the University of Virginia, and part of the committee that wrote the report. “They can actually do more harm than good and in fact don’t provide the skill training or replacement behaviors for youth that are suspended or expelled.”

The report also said zero-tolerance policies may lead to an underreporting of bullying because suspensions are perceived as too punitive.

Frederick Rivara, chairman of the committee and a professor of pediatrics and epidemiology at the University of Washington, cautioned that bullying has lasting negative consequences and cannot be ignored. “While there is not a quick fix or one-size-fits-all solution, the evidence clearly supports preventive and interventional policy and practice,” he said.

Programs that teach children how to get along with one another and what to do if they see kids who are being bullied, are more effective, Rivara said. Parents, too, can do their part, he said, by encouraging children to tell them if they’re being bullied, reporting it to the school or teacher and making sure their schools have effective anti-bullying programs in place.

Another committee member, Sandra Graham, a professor at UCLA, said schools need to be more proactive in teaching tolerance. “We need to be able to learn to live and accept and get along with people who are different from us,” she said.

“Bullies are often very popular … there are a lot of kids who bully to maintain their popularity and social status, so schools need to be addressing that,” Graham added.

Bullying behavior is seen as early as preschool and peaks during the middle school years, the researchers said. The problem has morphed from the traditional bully-in-the-schoolyard scenario to newer forms of electronic aggression, such as cyberbullying on social media sites.

The report said both bullies and their victims can suffer short and long-term consequences, including poor grades, anxiety and depression.

A government report this month on school crime from the National Center for Education Statistics and the Justice Department suggested bullying is down sharply from more than a decade ago. It found the percentage of public schools reporting bullying at least once a week decreased from 29 percent in 1999-2000, to 16 percent in 2013-14.

The National Academies was more cautious about trying to gauge the extent to which bullying is a problem across the country. In its report, it said bullying likely affects between 18 percent and 31 percent of young people. It had lower estimates for cyberbullying victims, saying it ranged from about seven to 15 percent of youngsters.

The committee also looked at the relationship between bullying and school shootings, but concluded that the data are unclear on the role of bullying as a factor or cause in the shootings. It also found no causal link between being bullied and suicide.