The National Institute of Mental Health (NIHM) has called off plans for a study examining a controversial type of treatment, called chelation therapy, that many critics say is an unethical experiment on children.

The agency said in a statement that it has cancelled a study aimed at assessing the effectiveness of a treatment called chelation.
Chelation therapy consists in the administration of chelating agents to remove heavy metals, such as lead, arsenic or mercury, from the body. Its use as a potential autism treatment is based on the theory that mercury in vaccines triggers autism.

Although many studies found no link between the vaccines and autism, some parents of autistic children continue to believe that mercury used in vaccines causes autism. Many parents refuse to vaccinate their children because they think the shots may cause autism or other health problems. Since 2001, with the exception of some flu shots, mercury hasn’t been used in routinely recommended childhood vaccines, according to the U.S. Centers for Disease Control and Prevention.

“NIMH has decided that resources are better directed at this time to testing other potential therapies for autism spectrum disorders, and is not pursuing the additional review required to begin the study,” said the institute which is a part of the U.S. National Institutes of Health.

NIMH received initial permission to begin the study in 2006. “In February 2007, based on new scientific data, an NIH Institutional Review Board reassessed the risk-benefit ratio of the proposed study. The board determined that there was no clear evidence for direct benefit to the children who would participate in the chelation trial and that the study presents more than a minimal risk,” the institute said in the statement. NIHM said it planned on using the money for the study on chelation therapy to test other therapies for autism.

Autism is a disability which typically appears during the first years of life and it affects the child’s ability to communicate and interact with others. There is no single cause of autism and most doctors believe is no cure.