Impact of Arsenic methylation of population exposed to chronic arsenic through drinking water

Abstract

Objective To investigate the arsenic methylation level of people chronically exposed to different levels of arsenic in drinking water. Methods A cluster sampling method was used to select 874 cases that had drank different concentration arsenic-contaminated water from arsenic endemic area in Bayannaoer City. They were divided into four groups according to arsenic exposure level: control (≤10 μg/L), low (> 10-50 μg/L), medium (> 50-200 μg/L) and high groups (> 200 μg/L), 146, 155, 224, 349 cases, respectively. The content of arsenic in drinking water and the arsenic species in urine were analyzed by inductively coupled plasma mass spectrometry (ICPMS), and the results were expressed as median. Results The inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and total-arsenic (tAs) in urine of low, medium and high groups increased following increasing of arsenic exposure level (χ2= 605.08, 609.96, 615.83, 628.64, all P 0.05). Compared to the ≤30 age group, the MMA, DMA and tAs of 31-45 age group increased and DMA, DMA%, PMI of ≥46 age group increased while iAs% decreased in high group (μg/L: 72.71 vs 109.13, 307.90 vs 419.50, 505.59 vs 684.60, 307.90 vs 418.26; 64.31% vs 68.45%, 0.79 vs 0.83, 20.71% vs 17.35%, χ2= 10.72, 10.24, 8.20, 10.24, 9.89, 20.96, 20.96, all P < 0.017). Compared to the 31-45 age group, DMA% and PMI of ≥46 age group increased while iAs% decreased (64.91% vs 68.45%, 0.80 vs 0.83, 20.14% vs 17.35%, χ2= 9.89, 20.96, 20.96, all P < 0.017). Conclusion There is a significant dose response relationship between arsenic metabolites and arsenic exposure level, and arsenic methylation is related to gender and age. Key words: Arsenic exposure; Methylation; Metabolism