Efficacy of succimer chelation of mercury at background exposures in toddlers: a randomized trial.

Objective: To examine whether succimer, a mercaptan compound known to reduce blood lead concentration in children, reduces blood mercury concentration.
Study Design: We used samples from a randomized clinical trial of succimer chelation for lead-exposed children. We measured mercury levels in pre-treatment samples from 767 children. We also measured mercury levels in blood samples drawn 1 week after treatment began (n = 768) and in a 20% random sample of the children who received the maximum 3 courses of treatment (n = 67). A bootstrap-based isotonic regression method was used to compare the trend with time in the difference between the adjusted mean mercury concentrations in the succimer group and that in the placebo group.
Results: The adjusted mean organic mercury concentration in the succimer group relative to the placebo group fell from 99% at baseline to 82% after 3 courses of treatment (P for trend = .048), but this resulted from the prevention of the age-related increase in the succimer group.
Conclusion: Succimer chelation for low level organic mercury exposure in children has limited efficacy.
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