(HealthDay) -- Ninety percent of American high school students report that some of their classmates are using illicit drugs, including alcohol and tobacco, during the school day, a new survey found.
When asked to estimate how many were involved, these teens reported that about 17 percent of students -- roughly 2.8 million -- are abusing drugs during the school day, according to the survey.
"The findings are alarming but not surprising," said Bruce Goldman, director of substance abuse services at Zucker Hillside Hospital, in Glen Oaks, N.Y. "We know that teens abuse alcohol, cannabis, prescription medications. It makes sense that they do it at school where they congregate with their peers.
Goldman was not involved with the survey, which was released Wednesday by the National Center on Addiction and Substance Abuse at Columbia University (CASAColumbia), in New York City.
The survey is a timely one, coming out soon after a U.S. government study found that more teenagers start drinking and smoking cigarettes and marijuana in June and July than in any other month.
The new survey also found that schools can be a hub of drug-dealing activity, with 44 percent of high schoolers saying they know a fellow student who sells drugs at their school.
Half of respondents knew of a place near their school where kids could go to drink and get high during the school day, according to the yearly back-to-school survey, which polled 1,003 12-to-17-year olds.
And more than one-third said that students had ample opportunity during the school day to drug, drink and smoke without getting caught.
Drug use in both public and private schools is on the rise, with 54 percent of private high school students reporting that drugs are available in their schools versus 24 percent in 2002 and 61 percent of students at public schools saying their schools are "drug infected," compared with 46 percent in 2002.
Social media seem to be contributing to the overall trend, with 75 percent of teens saying that seeing photos of other teens partying on Facebook, MySpace or other social networking sites made them want to do the same.
Nearly half of teens who have seen such pictures perceived that the teens in the photos "are having a good time."
Kids who had seen such photos were three to four times more likely to have used marijuana, alcohol or tobacco compared to kids who had not viewed this type of picture.
"Seeing teens partying with alcohol or marijuana on Facebook and other sites encourages other teens to want to party like that," said Emily Feinstein, project director for the survey and a senior policy analyst with CASAColumbia. "Clearly, parents really need to help children navigate that world safely."
The survey also looked specifically at parental supervision and parental expectations and found both to play a major role in teens' drug use.
Children who are left home alone overnight are about twice as likely to have used alcohol or marijuana and three times as likely to have used tobacco, compared to kids who are not left home alone.
Teens who believe their parents would not be "extremely upset" to know that their child was using drugs were less likely to engage in this type of behavior.
"Parents need to be hypervigilant and monitor their children's friends, both virtual and reality," Goldman said.
The same goes for school personnel, he added.
"If kids know who is using drugs, why don't the staff?" he asked.
Feinstein concluded, "Preventing addiction is all about preventing teen substance use because the developing brain is more vulnerable. We really need to look at this as a health care problem rather than a behavioral problem and start screening and intervening early."
Explore further: Summer is peak time for teens to try drugs, alcohol: report
More information: For more on teens and drugs, visit the American Academy of Child and Adolescent Psychiatry.