NASHVILLE -- A government move to limit a popular but scientifically unproven blood-cleansing technique in Tennessee has been quashed because of public protest.

The state Board of Medical Examiners voted unanimously Wednesday to back off the proposed regulations.

The decision came about a month after 150 people crowded into a hearing to protest the proposal.

The board also received more than 200 letters and a petition signed by 6,500 people.

"That's the end of these rules," said Dr. David L. Starnes, president of the board, after the vote.

About 80 people, most of them chelation supporters, cheered the decision.

Chelation is a procedure for removing lead from the body.

Doctors have reported the treatment also appears to improve symptoms of heart and peripheral vascular disease.

The American College for Advancement in Medicine, which promotes innovative therapies, estimates more than 500,000 Americans have undergone the treatment.

However, mainstream medicine and the U.S. Food and Drug Administration doubt the effectiveness.

In chelation, a compound called EDTA (ethylene diamine tetraacetic acid) and vitamins are given intravenously.

It "chelates" or binds to heavy metals such as lead in the blood so they can be excreted from the body in urine.

"I have several patients who are convinced that without chelation they wouldn't be alive today," said Dr. H. Joseph Holliday of Athens, who has administered more than 8,000 chelation treatments.

The state board was considering limiting use of the technique to "a carefully controlled clinical investigation in an academic institution because the procedure's results -- except for treating heavy metal poisoning -- are unproven."

The board instead decided that ethical regulations already in place for doctors are enough to protect against "promiscuous use of this treatment."

Board members said they are convinced that no action is the best action.

"I felt it was best not to try to make a rule when there was very little demonstrated harm" that could stem from the treatment, said Dr. David L. Cunningham, a Memphis neurosurgeon.