A controversial trial of chelation therapy for autism (see _Nature_ 454, 259; 2008) has been scrapped by the US National Institute of Mental Health, which says its resources are better directed elsewhere.

The study was first proposed in 2006, but was referred for further ethics review after a 2007 publication reported that chelating agents could cause cognitive problems in rats. Critics charged that the study would needlessly expose children with autism to risk for no medical gain.

The American Academy of Pediatrics has recommended that the treatment be reserved for children with serious heavy-metal poisoning. Still, it is in broad underground use by parents of children with autism, many of whom believe the disease is due to mercury in childhood vaccinations.