Determinants of arsenic methylation efficiency and urinary arsenic level in pregnant women in Bangladesh

Abstract

BackgroundPrenatal inorganic arsenic (iAs) exposure is associated with pregnancy outcomes. Maternal capabilities of arsenic biotransformation and elimination may influence the susceptibility of arsenic toxicity. Therefore, we examined the determinants of arsenic metabolism of pregnant women in Bangladesh who are exposed to high levels of arsenic.MethodsIn a prospective birth cohort, we followed 1613 pregnant women in Bangladesh and collected urine samples at two prenatal visits: one at 4–16 weeks, and the second at 21–37 weeks of pregnancy. We measured major arsenic species in urine, including iAs (iAs%) and methylated forms. The proportions of each species over the sum of all arsenic species were used as biomarkers of arsenic methylation efficiency. We examined the difference in arsenic methylation using a paired t-test between first and second visits. Using linear regression, we examined determinants of arsenic metabolism, including age, BMI at enrollment, education, financial provider income, arsenic exposure level, and dietary folate and protein intake, adjusted for daily energy intake.ResultsComparing visit 2 to visit 1, iAs% decreased 1.1% (p < 0.01), and creatinine-adjusted urinary arsenic level (U-As) increased 21% (95% CI: 15, 26%; p < 0.01). Drinking water arsenic concentration was positively associated with iAs% at both visits. When restricted to participants with higher adjusted urinary arsenic levels (adjusted U-As > 50 μg/g-creatinine) gestational age at measurement was strongly associated with DMA% (β = 0.38, p < 0.01) only at visit 1. Additionally, DMA% was negatively associated with daily protein intake (β = − 0.02, p < 0.01) at visit 1, adjusting for total energy intake and other covariates.ConclusionsOur findings indicate that arsenic metabolism and adjusted U-As level increase during pregnancy. We have identified determinants of arsenic methylation efficiency at visit 1.

Umbilical Cord Blood Metal Mixtures and Birth Size in Bangladeshi Children

“…The study population has been described previously (Gao et al 2019;Rahman et al 2017). During 2008 women with an ultrasound-confirmed singleton pregnancy of ≤16 wk gestation were recruited for a longitudinal prospective birth cohort study from two rural health clinics operated by the Dhaka Community Hospital Trust (DCH Trust) in the Sirajdikhan and Pabna Sadar Upazilas of Bangladesh.…”

As3MT and GST Polymorphisms Influencing Arsenic Metabolism in Human Exposure to Drinking Groundwater

“…Adults ≥ 63 may have significantly lower urinary excretions of DMA but higher those of InAs compared with young subjects [68]. Due to these contradictory findings and that aging can probably be associated with a variety of functional changes in the organs involved in the metabolism or retention of the metabolites of arsenic, their effect on arsenic metabolism needs to be confirmed [38]. On the other hand, in this work the alcohol consumption showed significant association with MMA and its interaction with As3MT enhance its effects.…”

“…This analysis could have a biological interpretation of "fast primary methylation step". Several authors have proposed the use of excretion ratios of MMA/InAs and DMA/MMA in the urine, also referred as primary methylation index (PMI) and secondary methylated index (SMI), respectively and used as surrogate biomarkers of the arsenic metabolic capacity [18,[38][39][40]. Nevertheless, SMI and PMI measurements only use information about two of the three species and completely fail to account for the dependence between the arsenic species outcomes which does not have a clear biological interpretation [41,42].…”

“…Likewise, although the forms of organic arsenic were not measured in our study, when we compared the total urinary arsenic concentration with the total sum of urinary arsenic metabolites, the median was very similar. These small differences could be due to other organic arsenic species, such as arsenobetaine (AsB) (abundant in crustacean seafood) increasing the total urinary arsenic concentration and excreted unchanged into the urine [38,72]. Therefore, this organic arsenic form appears to not influence DMA concentration.…”

MBP‐activated autoimmunity plays a role in arsenic‐induced peripheral neuropathy and the potential protective effect of mecobalamin

“…Arsenic (As) is a natural element and widely presents in the environment. It was estimated that approximate 200 million people all over the world were affected by high level of As in drinking water, with the most serious situation in Bengal Delta 1,2 . In rice‐producing area, As could be accumulated in rice through irrigation with As‐contaminated water, and consumption of rice was reported to be a prominent intake pathway in these districts 3,4 .…”