北京市场大米和小麦面粉中砷的含量及其形态分析

CONCENTRATION AND SPECIATION OF ARSENIC IN RICE GRAINS AND WHEAT FLOUR FROM BEIJING MARKET

以湖南省某污染区大米为对照,分析了北京市场大米、小麦面粉中总砷的含量水平和部分米中砷的形态.北京市场大米总砷的含量范围从未检出至0.218μg·g-1,算术平均值为0.097μg·g-1.湖南省某污染区大米总砷的含量范围为0.157—2.885μg·g-1,算术平均值为0.415μg·g-1,4例湖南省某污染区大米以无机砷为主,平均含量为0.341μg·g-1.北京市场面粉总砷的含量范围从未检出至0.057μg·g-1,算术平均值为0.006μg·g-1.有17例面粉样品未检出砷,占总样品的45%.与《食品中砷限量指标》(GB2762-2005)的限量值(大米无机砷0.15μg·g-1,面粉无机砷0.1μg·g-1)相比,北京市场的大米和面粉均未超标.湖南省某污染区4例大米无机砷含量全部超过限量标准,为标准的1.2—4.8倍.以WHO最大日允许无机砷摄入量2.1μg·kg-1bw·d-1为参照标准,普通成人每日通过北京市场大米和面粉摄入的无机砷相当于WHO最大日允许摄入无机砷量(MTDI)的13%和0.5%,通过湖南省某污染区大米摄入的无机砷则相当于MTDI的57%.

Arsenic concentration in polished rice and wheat flour from Beijing markets were investigated. Most samples were purchased from supermarkets and trade centers, and a few flour samples from local residents. There were 30 rice samples and 38 flour samples from Beijing, and 23 rice samples from contaminated areas in Hunan. Results showed that the concentrations of As in rice from Beijing ranged from below detection limit to 0. 218 μg·g^-1 the average concentrations of As was 0. 097 μg·g^-1 , ; Arsenic concentrations in rice from Hunan ranged from 0. 157 μg·g^-1 to 2. 885 μg·g^-1, with an average concentration of 0. 415 μg·g^-1 ; Arsenic concentrations in flour from Beijing ranged from below detection limit to 0. 057 μg·g^-1, with an average of 0. 006 μg·g^-1 Furthermore, arsenic was speciated by ion chromatography coupled with atomic fluorescence spectrometry. It was found that the dominant arsenic species was inorganic from contaminated area in Hunan and in four rice samples the concentration % inorganic arsenic all exceeded 0. 15 μg·g^-1 （GB2762 -2005 China National Standard）. By comparing WHO maximum tolerable daily intake MTDI for inorganic As, a grain As level of 0. 097 μg·g^-1 （ Beijing rice ） and 0. 415 μg·g^-1 （ Hunan contaminated rice ） would equate to 13% and 57% of the MTDI , respectively. It is clear that the health risk associated with arsenic in rice is higher for samples from contaminated area in Hunan than from Beijing market through daily consumption of rice.