Poison control centers are reporting an increase in the number of calls they are receiving for nicotine poisoning from e-cigarettes. This February, centers received 215 calls, compared with about one per month in 2010.

About half of calls related to nicotine poisoning from e-cigarettes involved children age 5 or younger, HealthDay reports. Dr. Tim McAfee, Director of the Centers for Disease Control and Prevention’s (CDC) Office on Smoking and Health, which published the findings, said many people don’t know liquid nicotine is toxic. “The time has come to start thinking about what we can do to keep this from turning into an even worse public health problem,” he said.

McAfee said the Food and Drug Administration is expected to propose regulations for e-cigarettes, and he hopes they include childproof caps and warning labels. “These things can be hardwired into these products, rather than being left to the whim of the manufacturer,” he said. McAfee urged e-cigarette users to keep the devices and their refills out of the reach of children. “These should be treated with the same caution one would use for bleach. In some ways, this is more toxic than bleach,” he said.

He explained liquid nicotine can be poisonous if it is swallowed, inhaled, or absorbed through the skin or membranes in the mouth, lips or eyes. It can cause nausea, vomiting or seizures.

In a CDC news release, Director Dr. Tom Frieden said, “E-cigarette liquids as currently sold are a threat to small children because they are not required to be childproof, and they come in candy and fruit flavors that are appealing to children.”