More than 1 million children living in the U.S. were victims of identity fraud in 2017, a new study revealed.

According to the “2018 Child Identity Fraud Study,” by Javelin Strategy & Research and sponsored by Identity Guard, identity theft caused $2.6 billion in total losses and $540 million in out-of-pocket costs for the families of the child victims.

The study surveyed 5,000 adults who lived with a dependent minor at some point in the past six years. 

The report found that data breaches are particularly damaging for young victims. Of the children who learned their information was exposed, 39 percent fell victim to identity fraud. That’s considerably higher than the rate for adults at just 19 percent.

That wasn’t the only area where child victims of identity fraud, which affected 16.7 million U.S. consumers in 2017, had different experiences than their adult counterparts. For example, more than half (60 percent) of children personally knew the perpetrators who abused their identity. By comparison, just 7 percent of adult victims knew their offender.

The study also showed that children who had been bullied online were nine times more likely to fall victim to identity fraud than those who weren’t, with incident rates of 6.67 percent and 0.72 percent, respectively.