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Toxicol Sci. 2016 Jul;152(1):29-39. doi: 10.1093/toxsci/kfw060. Epub 2016 Apr 7.

Arsenic Metabolism in Children Differs From That in Adults.

Author information

1
*Institute of Environmental Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden;
2
*Institute of Environmental Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden; marie.vahter@ki.se.
3
*Institute of Environmental Medicine, Karolinska Institutet, Stockholm, SE-171 77, Sweden; International Center for Diarrhoeal Disease Research, Bangladesh (Icddr,B), Dhaka 1000, Bangladesh;
4
Institute of Chemistry, Analytical Chemistry, NAWI Graz, University of Graz, Universitaetsplatz 1, Graz 8010, Austria.
5
International Center for Diarrhoeal Disease Research, Bangladesh (Icddr,B), Dhaka 1000, Bangladesh;

Abstract

Arsenic toxicity in adults is associated with methylation efficiency, influenced by factors such as gender, genetics, and nutrition. The aim of this study was to evaluate influencing factors for arsenic metabolism in children. For 488 children (9 years), whose mothers participated in a study on arsenic exposure during pregnancy (nested into the MINIMat trial) in rural Bangladesh, we measured urinary concentrations of inorganic arsenic (iAs) and its metabolites methylarsonic acid (MMA) and dimethylarsinic acid (DMA) by HPLC-HG-ICPMS. Methylation efficiency was assessed by relative amounts (%) of the metabolites. We evaluated the impact of factors such as maternal urinary metabolite pattern, arsenic exposure, gender, socioeconomic status, season of sampling, and nutritional factors, including erythrocyte selenium (Ery-Se), and plasma folate and vitamin B12.Children had higher %DMA and lower %iAs in urine compared to their mothers, unrelated to their lower exposure [median urinary arsenic (U-As) 53 vs 78 µg/l]. Surprisingly, selenium status (Ery-Se) was strongly associated with children's arsenic methylation; an increase in Ery-Se from the 5-95th percentile was associated with: +1.8 percentage points (pp) for %iAs (P  =  .001), +1.4 pp for %MMA (P  =  .003), and -3.2 pp for %DMA (P  <  .001). Despite this, Ery-Se was positively associated with U-As (5-95th percentile: +41 µg/l, P  =  .026). As expected, plasma folate was inversely associated with %iAs (5-95th percentile: -1.9 pp, P  =  .001) and positively associated with %DMA (5-95th percentile: +2.2 pp, P  =  .008). Children methylated arsenic more efficiently than their mothers. Also influencing factors, mainly selenium and folate, differed. This warrants further research.

KEYWORDS:

arsenic; children; folate; metabolism; methylation; selenium

PMID:
27056082
PMCID:
PMC4922540
DOI:
10.1093/toxsci/kfw060
[Indexed for MEDLINE]
Free PMC Article

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