| 1. |
- Cao, Yang, Associate Professor, 1972-, et al.
(författare)
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Does background postnatal methyl mercury exposure in toddlers affect cognition and behavior?
- 2010
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Ingår i: Neurotoxicology. - : Elsevier. - 0161-813X .- 1872-9711. ; 31:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Because the toxicological effects of mercury (Hg) are more serious in the developing central nervous system of children than adults, there are growing concerns about prenatal and early childhood Hg exposure. This study examined postnatal methylmercury (MeHg) exposure and cognition and behavior in 780 children enrolled in the Treatment of Lead (Pb)-exposed Children clinical trial (TLC) with 396 children allocated to the succimer and 384 to the placebo groups. Mercury exposure was determined from analyses of blood drawn 1 week before randomization and 1 week after treatment began when succimer had its maximal effect on blood Pb (PbB). The baseline MeHg concentrations were 0.54 microg/L and 0.52 microg/L and post-treatment concentrations were 0.51 microg/L and 0.48 microg/L for placebo and succimer groups, respectively. Because the baseline characteristics in the two groups were balanced and because succimer had little effect on MeHg concentration and no effect on the cognitive or behavioral test scores, the groups were combined in the analysis of MeHg and neurodevelopment. The children's IQ and neurobehavioral performance were tested at age 2, 5 and 7 years. We saw weak, non-significant but consistently positive associations between blood MeHg and IQ test scores in stratified, spline regression and generalized linear model data analyses. The behavioral problem scores were constant or decreased slightly with increasing MeHg concentration. Additional adjustment for PbB levels in multivariable models did not alter the conclusion for MeHg and IQ scores, but did confirm that concurrent PbB was strongly associated with IQ and behavior in TLC children. The effects of MeHg on neurodevelopmental indices did not substantially differ by PbB strata. We conclude that at the present background postnatal MeHg exposure levels of US children, adverse effects on children's IQ and behavior are not detectable.
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| 2. |
- Cao, Yang, Associate Professor, 1972-, et al.
(författare)
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Efficacy of succimer chelation of mercury at background exposures in toddlers : a randomized trial
- 2011
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Ingår i: The Journal of Pediatrics. - : Elsevier. - 0022-3476 .- 1097-6833. ; 158:3, s. 480-485.e1
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Tidskriftsartikel (refereegranskat)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 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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| 3. |
- Cao, Yang, Associate Professor, 1972-, et al.
(författare)
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The impact of succimer chelation on blood cadmium in children with background exposures : a randomized trial
- 2013
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Ingår i: The Journal of Pediatrics. - : Elsevier. - 0022-3476 .- 1097-6833. ; 163:2, s. 598-600
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Tidskriftsartikel (refereegranskat)abstract
- Succimer lowers blood lead concentrations in children, and the structure of succimer chelates of lead and cadmium are similar. Using blood samples from a randomized trial of succimer for lead poisoning, however, we found that succimer did not lower blood cadmium in children with background exposure.
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