(AP) A drug that is sometimes used to treat lead poisoning _ and is also believed by some parents to be effective against autism _ caused the deaths of two children last year, the government said Thursday.

One youngster was autistic; the other had lead poisoning.

The deaths mark the first documented link between a chelation drug and cardiac arrest in children, according to the Centers for Disease Control and Prevention. Both children were treated with a product called Endrate.

CDC officials are also looking into the 2003 death of a 53-year-old woman in Oregon who was given chelation therapy by a practitioner of natural medicine.

Mary Jean Brown, chief of the CDC's Lead Poisoning Prevention Branch, said hospital pharmacies should consider whether stocking Endrate is necessary, given its risks and the availability of other treatments.

The maker of Endrate, Hospira Inc., had no immediate comment.

Chelating agents are chemical compounds, injected or given orally, that latch on to metals in the body and carry them out through urine or feces. Chelation is commonly used for lead poisoning.

Some doctors have used chelation to treat autism, believing mercury or other heavy metals cause the condition's symptoms. However, medical evidence does not support that belief, and the drug is not approved for that use, CDC officials said.

Endrate is approved for treating certain heart rhythm disturbances and high concentrations of calcium triggered by a bone cancer.

Since at least 1978, federal health officials have warned against giving it to children with lead poisoning. Endrate's calcium-removing abilities can dangerously disrupt the body's chemistry, Brown said.

In August, a 5-year-old boy with autism died in Portersville, Pa., while receiving an infusion of Endrate in a physician's office. A coroner later ruled that the treatment killed the boy.

In February 2005, a 2-year-old girl with lead poisoning was treated with three chelating agents _ one of them Endrate _ and died at a hospital hours later from what an autopsy concluded was cardiac arrest due to depleted levels of calcium.