Relationships between serum vitamin B12 level and arsenic methylation capability, and risk of arsenicosis / 中华地方病学杂志

ABSTRACT

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 patients28 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 B12 (x2=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.