Analysis of urinary arsenic methylation metabolites in population exposed to arsenic through drinking water before and after water improvement / 中华地方病学杂志

ABSTRACT

Objective:To study the effect of water improvement on urinary arsenic methylation metabolism in population exposed to arsenic through drinking water.Methods:A cluster sampling method was used to select drinking water type arsenism areas in Bayannur City, Inner Mongolia Autonomous Region. Permanent residents lived in the arsenism areas for more than 10 years were selected as the survey subjects. Urine samples ( n = 874, 111, 145) were collected in 2004 (before water improvement), 2014 (4 years after water improvement) and 2017 (7 years after water improvement), respectively, and some subjects were followed up in 2014 and 2017. High performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used to detect different forms of arsenic metabolites in urine [inorganic arsenic (iAs), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA)], and total arsenic (tAs), the iAs percentage (iAs%), MMA percentage (MMA%), DMA percentage (DMA%), monomethylation rate (PMI), dimethylation rate (SMI), and the ratio of MMA to DMA (MMA/DMA) were calculated. The content and distribution of urinary arsenic metabolites in people exposed to arsenic before and after water improvement were compared and analyzed. Results:Compared with 2004, the levels of iAs, MMA, DMA, tAs and iAs% in urine of arsenic exposed population in 2014 were lower ( Z =-14.12,-12.79,-14.27,-14.21,-6.90, P < 0.001), the levels of MMA%, DMA% and PMI were higher ( Z =-3.22,-2.91,-6.90, P < 0.05); in the same drinking water arsenic exposed population, compared with 2004, the levels of iAs, MMA, DMA, tAs and iAs% in urine ( n = 48) were lower ( Z =-5.57,-5.53,-5.54,-5.55,-2.86, P < 0.05) in 2014, and PMI level was higher ( Z =-2.86, P = 0.004). Compared with 2014, the levels of iAs% and MMA/DMA in urine of arsenic exposed population in 2017 were lower ( Z =-4.97,-2.25, P < 0.05), the levels of MMA, DMA, tAs, DMA%, PMI and SMI were higher ( Z =-4.01,-5.39,-4.77,-4.61,-4.97,-2.25, P < 0.05); in the same drinking water arsenic exposed population, compared with 2014, the level of iAs% in urine ( n = 28) was lower ( Z =-2.87, P = 0.004) in 2017, the levels of DMA% and PMI were higher ( Z =-2.32,-2.87, P < 0.05). Conclusion:Water improvement could significantly reduce the levels of urinary arsenic metabolites iAs, MMA, DMA and tAs and increase the level of DMA% in arsenic exposed population.