I know that Oleander ( Nerium oleander ) is poisonous. Almost every book and webpage about this plant warns the readers. But how poisonous is this plant? I can touch the leaves without any skin irritation. I can prune it without using gloves. What happens if somebody ( a small child, a dog ) starts chewing a leaf?
According to INCHEM:
A single leaf may be lethal to a child (Shaw & Pearn, 1979).
Just below that:
One leaf of N. oleander may be sufficient to kill a sheep (Shaw & Pearn, 1979). The lethal dose of N. oleander leaves reported for several animal species is about 0.5 mg/kg.