Department of Environmental Health & Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
Department of Environmental Health Sciences, Columbia University Mailman School of Public Health, New York, NY, USA.
Environ Res. 2023 Oct 1;234:116453. doi: 10.1016/j.envres.2023.116453. Epub 2023 Jun 19.
Arsenic methylation converts inorganic arsenic (iAs) to monomethyl (MMA) and dimethyl (DMA) arsenic compounds. Body mass index (BMI) has been positively associated with arsenic methylation efficiency (higher DMA%) in adults, but evidence in pregnancy is inconsistent. We estimated associations between anthropometric measures and arsenic methylation among pregnant women in rural northern Bangladesh.
We enrolled pregnant women (n = 784) (median [IQR] gestational week: 14 [13, 15]) in Gaibandha District, Bangladesh from 2018 to 2019. Anthropometric measures were BMI, subscapular and triceps skinfold thicknesses, and mid-upper arm circumference (MUAC), fat area (MUAFA), and muscle area (MUAMA). Arsenic methylation measures were urinary iAs, MMA, and DMA divided by their sum and multiplied by 100 (iAs%, MMA%, and DMA%), primary methylation index (MMA/iAs; PMI), and secondary methylation index (DMA/MMA; SMI). In complete cases (n = 765 [97.6%]), we fitted linear, beta, and Dirichlet regression models to estimate cross-sectional differences in iAs%, MMA%, DMA%, PMI, and SMI per IQR-unit difference in each anthropometric measure, adjusting for drinking water arsenic, age, gestational age, education, living standards index, and plasma folate, vitamin B12, and homocysteine.
Median (IQR) BMI, subscapular skinfold thickness, triceps skinfold thickness, MUAC, MUAFA, and MUAMA were 21.5 (19.4, 23.8) kg/m, 17.9 (13.2, 24.2) mm, 14.2 (10.2, 18.7) mm, 25.9 (23.8, 28.0) cm, 15.3 (10.5, 20.3) cm, and 29.9 (25.6, 34.2) cm, respectively. Median (IQR) iAs%, MMA%, DMA%, PMI, and SMI were 12.0 (9.3, 15.2)%, 6.6 (5.3, 8.3)%, 81.0 (77.1, 84.6)%, 0.6 (0.4, 0.7), and 12.2 (9.3, 15.7), respectively. In both unadjusted and adjusted linear models, all anthropometric measures were negatively associated with iAs%, MMA%, and PMI and positively associated with DMA% and SMI. For example, fully adjusted mean differences (95% CI) in DMA% per IQR-unit difference in BMI, subscapular skinfolds thickness, triceps skinfold thickness, MUAC, MUAFA, and MUAMA were 1.72 (1.16, 2.28), 1.58 (0.95, 2.21), 1.74 (1.11, 2.37), 1.45 (0.85, 2.06), 1.70 (1.08, 2.31), and 0.70 (0.13, 1.27) pp, respectively.
Anthropometric measures were positively associated with arsenic methylation efficiency among pregnant women in the early second trimester.
砷的甲基化将无机砷（iAs）转化为单甲基（MMA）和二甲基（DMA）砷化合物。体重指数（BMI）与成人砷甲基化效率（更高的 DMA%）呈正相关，但在妊娠中的证据不一致。我们估计了孟加拉国北部农村地区孕妇的人体测量指标与砷甲基化之间的关联。
我们于 2018 年至 2019 年在孟加拉国盖班达区招募了 784 名孕妇（中位数[IQR]孕周：14[13,15]）。人体测量指标包括 BMI、肩胛下和肱三头肌皮褶厚度以及上臂中部周长（MUAC）、脂肪面积（MUAFA）和肌肉面积（MUAMA）。砷甲基化测量值为尿 iAs、MMA 和 DMA 除以它们的总和并乘以 100（iAs%、MMA%和 DMA%）、初级甲基化指数（MMA/iAs；PMI）和次级甲基化指数（DMA/MMA；SMI）。在完整的病例中（n=765[97.6%]），我们使用线性、β 和 Dirichlet 回归模型来估计每个人体测量指标每 IQR 单位差异的 iAs%、MMA%、DMA%、PMI 和 SMI 的横断面差异，同时调整饮用水砷、年龄、胎龄、教育、生活水平指数以及血浆叶酸、维生素 B12 和同型半胱氨酸。
中位数（IQR）BMI、肩胛下皮褶厚度、肱三头肌皮褶厚度、MUAC、MUAFA 和 MUAMA 分别为 21.5（19.4，23.8）kg/m、17.9（13.2，24.2）mm、14.2（10.2，18.7）mm、25.9（23.8，28.0）cm、15.3（10.5，20.3）cm 和 29.9（25.6，34.2）cm，中位数（IQR）iAs%、MMA%、DMA%、PMI 和 SMI 分别为 12.0（9.3，15.2）%、6.6（5.3，8.3）%、81.0（77.1，84.6）%、0.6（0.4，0.7）和 12.2（9.3，15.7）%。在未调整和调整后的线性模型中，所有人体测量指标均与 iAs%、MMA%和 PMI 呈负相关，与 DMA%和 SMI 呈正相关。例如，在 BMI、肩胛下皮褶厚度、肱三头肌皮褶厚度、MUAC、MUAFA 和 MUAMA 的每 IQR 单位差异的 DMA%完全调整后的平均差异（95%CI）分别为 1.72（1.16，2.28）、1.58（0.95，2.21）、1.74（1.11，2.37）、1.45（0.85，2.06）、1.70（1.08，2.31）和 0.70（0.13，1.27）pp。
在妊娠早期中期，人体测量指标与孕妇砷甲基化效率呈正相关。
