NIH Finds Succimer Ineffective for Mercury Removal

NIH Finds Succimer Ineffective for Mercury Removal

Succimer is a medication recently used as an alternative therapy for such conditions as autism. This was because researchers thought the drug effectively removed mercury from the body.

As autism and mercury poisoning are allegedly linked, succimer appeared to be a viable form of treatment. Research from the National Institutes of Health (NIH), however, has found that succimer does not adequately remove mercury.

“Succimer is effective for treating children with lead poisoning, but it does not work very well for mercury,” stated Walter Rogan, M.D., head of the Pediatric Epidemiology Group at the National Institute of Environmental Health Sciences. “Although it is not approved by the Food and Drug Administration to reduce mercury, succimer is reportedly being used for conditions like autism, in the belief that these conditions are caused, in part, by mercury poisoning. Our new data offers little support for this practice.”

Details of Succimer

According to the NIH, succimer is a chelating agent, which is a substance that can bind certain ions and remove them from solution. Although research has revealed that succimer effectively lowers blood concentrations of mercury after one week of treatment, continued therapy for five months has shown only to slow the rates at which children accumulate mercury. Studies have not yet revealed the safety of higher doses and longer treatment durations.

Dr. Rogan and researchers used blood samples from 767 different children who participated in a trial known as the Treatment of Lead-exposed Children (TLC). In that study, succimer lowered blood lead levels in 2-year-old children with moderate to high blood lead concentrations.

The blood samples were collected before treatment began, one week after treatment and then again at the three-month mark. Mercury concentrations were similar in all of the children before treatment. Concentrations eventually increased in both groups, but more slowly in the children given succimer. The drug produced a 42 percent difference in blood lead levels, but only an 18 percent reduction in blood mercury.

“Although succimer may slow the increase in blood mercury concentrations, such small changes seem unlikely to produce any clinical benefit,” Dr. Rogan stated.

“This research fills a gap in the scientific literature that could not be addressed any other way. We were fortunate to have samples already collected from toddlers who had been treated with succimer for lead poisoning allowing us to help answer this important question,” said Linda Birnbaum, Ph.D., director of NIEHS and the National Toxicology Program.

Mercury Poisoning

The NIH states mercury poisoning can be dangerous and even fatal. The majority of mercury exposure in the United States comes in the form of methylmercury. This is found in foods, and a primary source is certain fish. Mercury is also found in amalgam dental fillings and energy-saving fluorescent light bulbs. Mercury emissions produced by coal-burning power plants can enter the food chain as well. Vaccines also contain a form of mercury called ethylmercury.

Mercury is considered to be one of the most toxic natural substances. The heavy metal evaporates at room temperature, becomes a gas, enters the body, crosses the blood-brain barrier and gets trapped inside the brain. It accumulates over time and may interfere with cognitive functions.

Mercury exposure is believed to affect nervous system development and contribute to autism. Extensive studies, however, have found no conclusive link between vaccines and autism. As a precautionary measure, mercury compounds have been reduced or eliminated from most standard childhood vaccines.

New research from Northeastern University professor Richard Deth also suggests long-term exposure to mercury may cause Alzheimer’s-like symptoms in people. Those symptoms include memory loss and confusion. The study lacks sufficient evidence to conclude that mercury exposure is the source of such problems. However, emerging data supports the need to minimize exposure.

“Mercury is clearly contributing to neurological problems, whose rate is increasing in parallel with rising levels of mercury,” stated Deth, a professor of pharmacology in the Bouve College of Health Sciences. “It seems that the two are tied together.”


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