Arsenic methylation patterns before and after changing from high to lower concentrations of arsenic in drinking water.
Arsenic methylation patterns before and after changing from high to lower concentrations of arsenic in drinking water.
复制标题
从饮用水中从高浓度到较低浓度的砷之前和之后的砷甲基化模式。
DOI：
10.1289/ehp.961041200
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发表时间：
1996-11
影响因子：
10.4
通讯作者：
Smith AH
中科院分区：
文献类型：
--
作者：
Hopenhayn-Rich C;Biggs ML;Kalman DA;Moore LE;Smith AH
无机砷（In-As）是一种职业性和环境致癌物，可通过生物甲基化生成一甲基胂酸酯（MMA）和二甲基胂酸酯（DMA）。有人提出，高暴露水平下甲基化能力的饱和可能导致In-As致癌性的阈值。尿In-As、MMA和DMA的相对分布被用来衡量人的甲基化能力。在世界范围内，最常见的环境暴露途径是通过饮用水。我们在智利北部对长期暴露于高砷含量（600微克/升）自然污染的水的人群进行了一项生物标志物研究。在本文中，我们介绍了对73名接触者进行前瞻性随访的结果，这些人被提供了低砷含量（45微克/升）的水2个月。比较干预前后尿中in - as、MMA、DMA的比例，分析其他因素对砷代谢物分布的影响。这项研究的结果表明，砷暴露的减少与尿液中in - as百分比（从17.8%降至14.6%）和MMA/DMA比率（从0.23降至0.18）的小幅下降有关。其他因素如吸烟、性别、年龄、居住年限和种族主要与MMA/DMA比值的变化相关，其中吸烟的影响最大。然而，所调查的因素仅占观察到的大个体间差异的20%左右。甲基化酶的遗传多态性和其他辅助因素可能导致一些无法解释的变异。观察到的in - as百分比和MMA/DMA比率的变化不支持基于暴露的人体砷甲基化阈值。
Inorganic arsenic (In-As), an occupational and environmental human carcinogen, undergoes biomethylation to monomethylarsonate (MMA) and dimethylarsinate (DMA). It has been proposed that saturation of methylation capacity at high exposure levels may lead to a threshold for the carcinogenicity of In-As. The relative distribution of urinary In-As, MMA, and DMA is used as a measure of human methylation capacity. The most common pathway for elevated environmental exposure to In-As worldwide is through drinking water. We conducted a biomarker study in northern Chile of a population chronically exposed to water naturally contaminated with high arsenic content (600 micrograms/l). In this paper we present the results of a prospective follow-up of 73 exposed individuals, who were provided with water of lower arsenic content (45 micrograms/l) for 2 months. The proportions of In-As, MMA, and DMA in urine were compared before and after intervention, and the effect of other factors on the distribution of arsenic metabolites was also analyzed. The findings of this study indicate that the decrease in arsenic exposure was associated with a small decrease in the percent In-As in urine (from 17.8% to 14.6%) and in the MMA/DMA ratio (from 0.23 to 0.18). Other factors such as smoking, gender, age, years of residence, and ethnicity were associated mainly with changes in the MMA/DMA ratio, with smoking having the strongest effect. Nevertheless, the factors investigated accounted for only about 20% of the large interindividual variability observed. Genetic polymorphisms in As-methylating enzymes and other co-factors are likely to contribute to some of the unexplained variation. The changes observed in the percent In-As and in the MMA/DMA ratio do not support an exposure-based threshold for arsenic methylation in humans.