How much ingested Americium 241 will kill someone?

Injested 241 will take a while to do the job because alphas don't travel far but are very damaging. I believe you would notice the ozone from the dose and not swallow it. But I digress--- the fatal dose varies with the individual but it is generally acknowleged that a 300-500 RAD dose to the gut will do enough damage to bring about the death of the lining and the subsequent internal bleeding is usually fatal with no treatment. The amount to do this would depend on the speed that the body procesed the material through the stomach and gut.