Efficacy of Succimer Chelation of Mercury at Background Exposures in Toddlers: A Randomized Trial

Abstract

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 in pre-treatment samples from 767 children. We also measured mercury 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 over time in the difference between the adjusted mean mercury concentrations in the succimer group and 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 three courses of treatment (p for trend = 0.048), 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.

Postnatal exposure to methyl mercury and neuropsychological development in 7-year-old urban inner-city children exposed to lead in the United States

“…White children had lower MeHg concentration than non-white children. Succimer had little effect on MeHg concentrations and no effect on test scores (Rogan et al, 2001; Cao et al, 2011); therefore we combined the two treatment groups for analysis. The geometric mean for Hg at age 7 years was close to that at age 2 years, but a child’s concentrations at the 2 time points were only weakly correlated with each other (Pearson correlation coefficient = 0.15).…”

“…We also demonstrated that chelation therapy with succimer had no discernible impact on toddler’s blood MeHg concentrations at background levels (Cao et al, 2011). Furthermore, unlike other metals such as manganese and cadmium (e.g., Kim et al, 2012; Henn, et al, 2011), there is presently no evidence of toxic synergisms between MeHg and Pb (Cao et al 2010).…”

The Impact of Succimer Chelation on Blood Cadmium in Children with Background Exposures: A Randomized Trial

“…The two treatment groups were balanced with respect to baseline characteristics 15 . The proportions of censored data are 43% and 45% for baseline and 1-week respectively, which did not affect the estimates of percentiles above the median.…”

Diagnosis and Treatment of Metal Poisoning

“…DMSA can also be used in the treatment of acute inorganic mercury and organic mercury intoxications (Boscolo et al, 2009;Risher and Amler, 2005). In a study of children aged 12 to 33 months, succimer treatment gave a modest reduction in organic mercury concentration after 1 week, and slowed or prevented the accumulation of organic mercury after multiple courses over 5 months (Cao et al, 2011). No effect was seen on blood cadmium levels in the same group (Cao et al, 2013).…”