血清维生素B12水平与砷甲基化能力及砷中毒风险的关系研究

Relationships between serum vitamin B12 level and arsenic methylation capability, and risk of arsenicosis

目的了解不同血清维生素B12水平与砷暴露人群砷甲基化能力及砷中毒发病风险的关系。方法在云南大理弥渡县的3个村，采用横断面调查方法，选择研究对象103人，按照饮水砷暴露情况及是否为砷中毒患者将研究对象分为3组，分别为对照组（28例，无高砷暴露）、砷暴露患者组（30例）、砷暴露非患者组（45例）。采集研究对象即时尿样及外周血血样，应用氢化物发生一冷井捕集．原子吸收分光光度法测定尿中各形态砷含量，化学发光免疫法测定血清中维生素B12水平。比较不同组别人群尿中各形态砷含量及血清维生素B12水平，探讨不同水平血清维生素B12人群砷中毒发病情况，分析血清维生素B12水平与砷甲基化代谢能力的相关性。结果各组人群尿中无机砷（iAs）、一甲基砷（MMA）、二甲基砷（DMA）、总砷（tAs）含量比较差异均有统计学意义（F=13．032、20．778、21．978、22．155，P均〈0．05），砷暴露患者组[（94．56±107．62）、（75．76±54．31）、（270．19±185．10）、（444．02±323．28）μg／gCr]和砷暴露非患者组[（40．05±47．47）、（45．11±46．06）、（183．91±151．45）、（270．84±231．45）μg/gCr]均显著高于对照组[（7．58±4．82）、（4．27±2．01）、（26．89±11．45）、（38．91±13．34）μg／gCr，P均〈0．05]。各组人群血清维生素B12水平比较差异有统计学意义（F=6．650，P〈0．05），砷暴露患者组[（366．05±120．03）ng/L]显著低于对照组[（533．70±180．12）ng／L，P〈0．05]。不同水平血清维生素B12人群砷中毒患病率比较差异有统计学意义（x^2=8．13，P〈0．05），血清维生素B12水平越低的人群，砷中毒的发病情况越严重。血清维生素B12水平与尿MMA％呈负相关（r=-0．21，P〈0．05），与二甲基化率（SMR）呈正相关（r=0．21，P〈0．05）。结论血清维生素B12水平低的人群砷中毒的发病风险增高。

Objective To investigate the relationship between serum vitamin B12 level and arsenic methylation and the risk of arsenic poisoning in the arsenic exposed population. Methods Three villages in Midu County, Dali City, Yunnan Province were investigated. Cross-sectional study was used to select 103 subjects. The population was divided into three groups according to drinking water arsenic exposure situation and whether arsenic poisoning patients： 28 cases of control group （not exposed to high arsenic）, 30 cases of arsenic patient group and 45 cases of non patient group. Instant peripheral blood samples and urine samples were collected. The content of arsenic in urine was determined by hydride generation cold trap and atomic absorption spectrophotometry. The levels of vitamin B12 in serum were determined by chemiluminescence immunoassay. The urine arsenic and serum vitamin B12 contents in different groups were compared, the arsenic poisoning prevalence rate in people with different levels of serum vitamin B12 was investigated, and the correlation between serum vitamin B12 level and the metabolism of arsenic methylation was analyzed. Results The level of urinary inorganic arsenic （iAs）, monomethylated arsenic （MMA） and dimethylated arsenic （DMA）, total arsenic （tAs） were significantly different between groups （F = 13.032,20.778, 21.978, 22.155, all P 〈 0.05）. The levels of urine arsenic in patients with arsenic exposure [（94.56 ± 107.62）, （75.76 ± 54.31）, （270.19 ± 185.10）, （444.02 ± 323.28） μg/g Cr] and non patient with arsenic exposure [（40.05 ± 47.47）, （45.11 ± 46.06）, （183.91± 151.45）, （270.84 ± 231.45）μg/g Cr] were significantly higher than those in control group [（7.58 ± 4.82）, （4.27 ± 2.01）, （26.89 ± 11.45）, （38.91 ± 13.34） μg/g Cr, all P 〈 0.05]. The serum levels of vitamin B12 were significantly different between groups （F = 6.650, P 〈 0.05）, patients exposed to arsenic [（366.05 ± 120.03） ng/L] was significantly lower than the control group [（533.70 ± 180.12） ng/L, P 〈 0.05]. There were significant differences in the detection rate of arsenic poisoning among different levels of serum vitamin Bl2 （x^2 = 8.13, P 〈 0.05）, the lower dose of vitamin B12, the more serious the incidence of arsenic poisoning. The content of vitamin B12 was negatively correlated with MMA% （r = - 0.21, P 〈 0.05）, and positively correlated with SMR （r = 0.21, P 〈 0.05）. Conclusion Low levels of vitamin B12 in serum may increase the risk of arsenic poisoning.