The standard treatment for patients who have attempted suicide by drinking pesticide -- a major problem in parts of rural South Asia and China -- is essentially useless, according to a study.
Activated charcoal, taken orally, has long been prescribed as an antidote for self-inflicted poisoning, as it is thought to absorb toxins in the stomach and prevent them from entering the bloodstream.
But a large clinical study of 4,500 patients, published in Saturday's issue of The Lancet, has found that the carbon powder has no discernible effect.
A team of researchers led by Michael Eddleston of the Scottish Poisons Information Bureau in Edinburgh compared three different treatments for suicide attempts in rural Sri Lanka in 2002 and 2003.
A third of the subjects were given a single, 50-gramme dose of charcoal, and one third were given six 50-gramme doses at four-hour intervals.
For the last third, activated charcoal was omitted entirely from the treatment administered, according to the study.
Mortality rates for all three groups showed no statistically significant difference, varying by less than one percent. On average, 6.8 percent of the patients died as a result of the poisoning.
The percentage needing intubation for breathing, or suffering from seizures, was likewise similar across the three sets of patients, with a slightly lower incidence among those who received multiple doses of charcoal.
Just over half -- 51 percent -- of the subjects ingested industrial insecticides and 36 percent swallowed toxic seeds from yellow oleander, a common roadside plant throughout most of south Asia.