MILWAUKEE (AP) — Curious toddlers find the drugs in a mother’s purse or accidentally dropped on the floor. Sometimes a parent fails to secure the child-resistant cap on a bottle of painkillers.

No matter how it happens, if a 35-pound toddler grabs just one opioid pill, chews it and releases the full concentration of a time-released adult drug into their small bodies, death can come swiftly.

These are some of the youngest victims of the nation’s opioid epidemic – children under age 5 who die after swallowing opioids. The number of children’s deaths is still small relative to the overall toll from opioids, but toddler fatalities have climbed steadily over the last 10 years.

In 2000, 14 children in the U.S. under age 5 died after ingesting opioids. By 2015, that number climbed to 51, according to the Centers for Disease Control and Prevention. In Milwaukee County, Wisconsin, alone, four children died last year of accidental overdoses. Another 2-year-old perished in January.