Background

Arsenic (As) is considered to be toxic for humans, the main routes of exposure being through drinking water and the diet. Once ingested, inorganic arsenic can be methylated sequentially to monomethyl and dimethyl arsenicals. Several factors can affect both As exposure and methylation efficiency.

Objectives

To describe the urinary concentrations of the different As species and evaluate the methylation efficiency during pregnancy, as well as their associated factors in a birth cohort of pregnant Spanish women.

Methods

Participants in this cross-sectional study were 1017 pregnant women from two areas of Spain who had taken part in the INMA (Environment and Childhood) project (2003-2008). Total As (organic and inorganic compounds) and its main metabolites (monomethylarsonic acid, [MMA], dimethylarsinic acid, [DMA], inorganic As [iAs]) and arsenobetaine [AB]) were measured in urine samples collected during the first trimester. Sociodemographic and dietary information was collected through questionnaires. Multivariate linear regression models were used to explore the association between As species concentrations and covariates. Arsenic methylation efficiency was determined through the percentages of the metabolites and using As methylation phenotypes, obtained from principal component analysis.

Results

Median urine concentrations were 33.0, 21.6, 6.5, 0.35 and 0.33 μg/creatinine for total As, AB, DMA, MMA and iAs, respectively. Daily consumption of rice and seafood during the first trimester of pregnancy were positively associated with the concentration of As species (i.e., β [CI95%] = 0.36 [0.09, 0.64] for rice and iAs, and 1.06 [0.68, 1.44] for seafood and AB). TAs, AB and iAs concentrations, and DMA and MMA concentrations were associated with legume and vegetable consumption, respectively. The medians of the percentage of As metabolites were 89.7 for %DMA, 5.1 for %MMA and 4.7 for %iAs. Non-smoker women and those with higher body mass index presented a higher methylation efficiency (denoted by a higher %DMA and lower %MMA).

Discussion

Certain dietary, lifestyle, and environmental factors were observed to have an influence on both As species concentrations and methylation efficiency in our population. Further birth cohort studies in low exposure areas are necessary to improve knowledge about arsenic exposure, especially to inorganic forms, and its potential health impact during childhood.

中文翻译：

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妊娠期尿中砷的种类和甲基化效率：西班牙孕妇中的浓度和相关因素

背景

砷（As）被认为对人体有毒，接触的主要途径是通过饮用水和饮食。摄入后，可以将无机砷依次甲基化为一甲基和二甲基砷。有几个因素会影响砷暴露和甲基化效率。

目标

在西班牙孕妇的出生队列中，描述不同砷物种的尿液浓度并评估其在怀孕期间的甲基化效率及其相关因素。

方法

这项横断面研究的参与者是来自西班牙两个地区的1017名孕妇，他们参加了INMA（环境与儿童）项目（2003-2008年）。在孕早期的尿液样本中测量了总砷（有机和无机化合物）及其主要代谢产物（单甲基砷酸，[MMA]，二甲基砷酸，[DMA]，无机砷[iAs]）和砷甜菜碱[AB]。通过调查表收集了社会人口统计学和饮食信息。多元线性回归模型用于探索砷物种浓度与协变量之间的关联。砷的甲基化效率通过代谢物的百分比确定，并使用从主成分分析中获得的As甲基化表型确定。

结果

总As，AB，DMA，MMA和iAs的尿中位数浓度分别为33.0、21.6、6.5、0.35和0.33μg/肌酐。怀孕前三个月的大米和海鲜的日摄入量与砷物种的浓度呈正相关（即，大米和iAs的β[CI95％] = 0.36 [0.09，0.64]，海鲜的β[CI95％] = 0.36 [0.09，0.64]）和AB）。TAs，AB和iAs的浓度以及DMA和MMA的浓度分别与豆类和蔬菜的消费量相关。对于％DMA，As代谢产物百分比的中位数是8％，对于MMA是5.1，对于％iAs是4.7。非吸烟女性和体重指数较高的女性甲基化效率较高（以较高的％DMA和较低的MMA表示）。

讨论

观察到某些饮食，生活方式和环境因素对我们人口中砷物种的浓度和甲基化效率都有影响。在低暴露地区进行进一步的出生队列研究对于提高对砷（尤其是无机形式）的暴露及其在儿童期对健康的潜在影响的了解是必要的。