On any given day in 2012, there were about 2,400 teenagers serving time in adult state or federal prisons. And those teenagers were more likely to commit suicide than were inmates from any other age group.

This chart, based on data from the Bureau of Justice Statistics, shows the suicide rates of state prisoners from 2001-2012 and drive home just how at-risk teenage inmates can be:

In other words, teenagers in adult prisons are twice as likely to commit suicide as are adults in adult prisons. And they're far more likely to commit suicide than teenagers who are in juvenile detention or in alternative programs. A 2007 report from the advocacy group the Campaign for Youth Justice found that juveniles in adult prisons are 36 times more likely to commit suicide than are juveniles in juvenile detention.

Fortunately, the number of teenagers in adult prisons has declined over the last decade. In 2002, there were 3,000 teenagers in state or federal prison; throughout 2008 to 2012, there were 2,500 or fewer.

"I can't take it anymore. I give up"

Even after they're released from prison, the experience of being a teenager in an adult criminal-justice system can be hazardous to mental health. That's what happened to Kalief Browder, who was the subject of a 2014 New Yorker feature about the three years he spent in jail on Rikers Island waiting to be put on trial for stealing a backpack. (The trial never actually happened; instead, the prosecutor dismissed the charges and Browder was released.)

Browder tried to commit suicide at least three times while in jail. And in June 2015, two years after his release, he made another attempt and succeeded.

Here's how the New Yorker story describes what jail did to Browder:

For one thing, (Browder's brother) says, Browder was losing weight. "Several times when I visited him, he said, ‘They're not feeding me,' " the brother told me. "He definitely looked really skinny." In solitary, food arrived through a slot in the cell door three times a day. For a growing teen-ager, the portions were never big enough, and in solitary Browder couldn't supplement the rations with snacks bought at the commissary. He took to begging the officers for leftovers: "Can I get that bread?" Sometimes they would slip him an extra slice or two; often, they refused. Browder's brother also noticed a growing tendency toward despair. When Browder talked about his case, he was "strong, adamant: ‘No, they can't do this to me!' " But, when the conversation turned to life in jail, "it's a totally different personality, which is depressed. He's, like, ‘I don't know how long I can take this.' " Browder got out of the Bing in the fall of 2011, but by the end of the year he was back-after yet another fight, he says. On the night of February 8, 2012 — his six-hundred-and-thirty-fourth day on Rikers — he said to himself, "I can't take it anymore. I give up." That night, he tore his bedsheet into strips, tied them together to make a noose, attached it to the light fixture, and tried to hang himself. He was taken to the clinic, then returned to solitary. Browder told me that his sheets, magazines, and clothes were removed — everything except his white plastic bucket.

Imprisoning teenagers as adults is unsafe for them and others

As I've written, putting teenagers in adult prisons doesn't just increase their danger to themselves. They're much more vulnerable to assault from other inmates. And teenagers who get treated as hardened criminals while they're still high-school-aged are more likely to engage in violence when they do get out of prison:

The problem with trying and incarcerating teenagers as adults is that it's something of a self-fulfilling prophecy. Juveniles get treated as adults, in theory, because they've committed particularly serious or violent crimes — but even when controlling for the seriousness of the crime, and other factors, kids who have been imprisoned in adult prisons are more likely to commit further acts of violence than those who serve their time in juvenile facilities.

Much of this is because adult prisons don't have the counseling and education resources that juvenile ones do. If juvenile facilities are, at their best, designed to prevent kids from being incarcerated again, adult prisons have mostly given up on that aspiration. Instead, staff at adult prisons just hope for order — even if it comes at the hands of prison gangs and ethnic or regional cliques. Anthony Pleasant, a young man from DC who spent ten years in federal prison starting when he was 16, says, "A warden, anybody will tell you, they allow the yard to run itself."

For teenagers, serving in adult prison is a basic risk to their personal safety. "I was with a lot of people who had life, and I had peanut time compared to them," Pleasant says. "If they had wanted to harm me, they would have done it and smiled afterward, because it meant nothing to them. Because they got life."

Juveniles can also develop unsavory associates that will encourage them to commit more crimes after they get out. Pleasant knew one boy in prison who was sentenced to adult prison at the age of 16, and ended up "put in a situation where he had to harm somebody." He got a new conviction after the incident, for 25 years.