Water quality improvement is the most efficient way to prevent arsenic exposure. After the cessation of arsenic ingestion, arsenic methylation capacity of the exposed population can change significantly. The factors associated with these changes remain poorly understood. Therefore, arsenic methylation capacity in a study cohort was estimated before and after water quality improvement in the present study. Results indicated that urinary content of the arsenic species in the study cohort significantly decreased after water quality improvement. In addition, the proportions of inorganic arsenic (%iAs) and monomethyl arsenic acid (%MMA) were significantly decreased, while proportions of dimethyl arsenic (%DMA) increased. The primary methylation index (PMI) and secondary methylation index (SMI) increased from 0.85 to 0.92 and 0.82 to 0.84, respectively. Arsenic species urinary content and arsenic methylation index varied slightly between the study cohort after water quality improvement and the control cohort. The rate of increase in PMI was higher than that in SMI. The study group aged 31–50 years had the highest increase in PMI. Logistic regression revealed that %DMA before water quality improvement was negatively associated with the increase in PMI, while %iAs were positively related, and %MMA were positively associated with the increase in SMI. It is concluded that urinary arsenic species content and arsenic methylation capacity increased to the levels of the control cohort after water quality improvement. An increase in primary arsenic methylation capacity may be a burden on the secondary arsenic methylation capacity. The main role of arsenic methylation capacity recovery may be the cessation of arsenic exposure.

水质的改善是防止砷暴露的最有效方法。砷摄入停止后，接触人群的砷甲基化能力可能发生显着变化。与这些变化相关的因素仍然知之甚少。因此，在本研究中，对研究人群中砷甲基化能力的估算是在水质改善前后。结果表明，研究人群中砷的尿含量在水质改善后显着降低。此外，无机砷（％iAs）和单甲基砷酸（％MMA）的比例显着降低，而二甲基砷（％DMA）的比例增加。一级甲基化指数（PMI）和二级甲基化指数（SMI）分别从0.85增至0.92和0.82至0.84。在水质改善后的研究人群和对照人群之间，砷种类的尿含量和砷甲基化指数略有不同。PMI的增长率高于SMI。31至50岁的研究组的PMI增幅最高。Logistic回归显示，水质改善前的DMA与PMI的增加呈负相关，而％iA与PMI的增加呈正相关，而MMA与SMI的增加呈正相关。结论是，水质改善后，尿中砷的含量和甲基化能力增加到对照组的水平。初级砷甲基化能力的增加可能是次级砷甲基化能力的负担。