Exposure Assessment Studies For Inorganic Arsenic In Chinese Rice

This paper aimed at developing an efficient, quick, stable and cheap rice iAsdetermination analytical method, with which we would monitor and assess theinorganic exposure situation in Chinese population. Trifluoroacetic acid （TFA）,hydrochloric acid, nitric acid, and acetic acid were taken into comparison for riceiAs extraction using SRM1568a and real rice sample as analytes. Meanwhile, theextraction modes ultrasonic and microwave were compared with heat extraction.For detection, both atomic fluorescence spectrometry （AFS） and inductivelycoupled plasma mass （ICP-MS） were optimized for As species separation anddetection. Took the efficiency, stability and cost of the method into consideration,best determination method were decided. Samples for exposure assessment were446whole grain samples collected from15Chinese provinces, which embrace themain rice-producing areas in China. All the grains were preliminary machined intoboth polished and unpolished rice flour. SRM1568a was contained in each batch ofdetermination to control the quality of our results. Point assessment was utilized fordata analysis to evaluate situation of iAs exposure in China.Through the comparision of the four extraction acid, besides TFA,0.15MHNO3was found to have satisfied effect and stability. Heat was efficient and theextraction temperature was decided to be90℃, last for2.5h. Determination resultsof SRM1568a were right in the reference range. Recoveries of different spike levelsin SRM1568a and real rice sample were98.71%¹11.71%（n=4）, with all RSD＜5%. Although, ultrasonic and microwave also had good effects of extraction, thecosts of their equipments were much higher than heat, and hard to popularize.Among all the samples As（Ⅲ） was the predominant species, secondly were As（Ⅴ）and DMA. The content ranges of inorganic arsenic in both polished and unpolishedrice were0²06.4ng/g and0⁴45.5ng/g with average contents of58.4ng/g and131.5ng/g, rarely exceed150ng/g, which were much lower than the predecessors’results in China. Samples from Jiangxi showed the highest inorganic arsenicconcentration which was95.3μg/kg, and the lowest was Jiangsu33.2μg/kg. Dailyaverage intake of inorganic arsenic was0.25μg/kg^-1bw·d^-1which was11.52%ofprovisional tolerable daily intake requirement （PTDI）, and MOE value of themedian exposure level was13. Through the comparison of our data and the resultsof EU, Japan, Australia and USA, our inorganic arsenic content was at therelatively lowest level. China is one of the biggest rice consumption and exportion countries in the world, with which in mind, rice is still the mian exposure rotine foriAs and need for increased vigilance.