Laboratory tests confirmed that two-year-old Alexei Wiltsey and his three-year-old brother Peter died of oleander toxicity, coroner's office spokesman Scott Carrier said. The two were found dead in their cribs at their El Segundo home on May 4.
The chemical oleandrian in the popular garden plant causes the heart to stop beating, Carrier said, adding the deaths were the first-ever fatal oleander cases in the county.
Death by oleander toxicity is extremely rare. The coroner had to contract with an outside laboratory to confirm the cause of death.
That the boys died from eating the plant was no surprise to Scott Appell, director of education at the Horticultural Society of New York.
"They're wonderful garden subjects, but they can kill you," Appell told CBS News Early Show Anchor Bryant Gumbel. "Oleander is lethal. One leaf alone is enough to kill an adult."
Oleander is among several common household and garden plants that can kill, Appell said.
"I have read reports where families had unintentionally poisoned because they used the branches as shish kabob skewers," he added. "These youngsters didn't have to go eat a whole bush. Not at all. Just one leaf."
The boys' mother, Shirley Wiltsey, said she found the boys chewing oleander leaves a few days before they died and noticed they had picked some again the night of their deaths.
Shirley and her husband Tom adopted the boys last August from an orphanage in Siberia. Authorities had speculated that the deaths were related to an rare mental disorder caused by the boys' having been born in hunger and poverty.
Although the plant is fatal for adults and children, the children's small size probably made them more susceptible to the poison than an adult would be, Appell said. Pets can also be poisoned.
The plants must be ingested or swallowed to be poisonous, and care should be taken to avoid inadvertent poisonings, Appell said.
"If I was out in the garden pruning them, if I lived in Florida or California, I'd wash my hands (afterwards) by all means," he said.
Like Azalea, English Ivy, Foxglove, Lily of the Valley, Mistletoe, and other fatal plants, oleander developed a killing chemical constituency to help it survive, Appell said. He listed several plants for CBS HealthWatch.
"If you're poisonous and you're a plant, it's a survival tactic. Insects that eat you will die," he said. "It helps them (plants) survive."
The best way to guard against poisonous plants is to know what's poisonous and what isn't, he said.
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