Arsenic accumulation and speciation in two rice varieties and related health risks

Arsenic is toxic and carcinogenic,so consumption of arsenic accumulated rice may produce serious health risks. Rice varieties (Oryza sativa L.) that accumulate the least arsenic,especially in the rice grain,are desired. Two rice varieties,named Weiyou 402(WY) and Eryou 416(EY) were selected to grow in arsenic spiked soils (0,10,20 and 40 mg·kg-1 arsenic) and arsenic soils (1∶1 of geogenic high level arsenic soil from Guizhou province and silt loam soil from Beijing) in a greenhouse,to compare their arsenic uptake,accumulation,speciation and related health risks. Arsenic was found to greatly inhibit the growth of the two rice varieties,including the biomass of shoots and roots,plant height and the number of spikes,however,EY was less affected than WY by the arsenic treatments. Arsenic in rice grain increased with the addition of arsenic in soils,both in WY and EY,with no difference between the two varieties; however,in natural arsenic soils,EY accumulated significantly less arsenic in rice grain than that of WY,with average arsenic contents measured as 0.062 and 0.278 mg·kg-1 for EY and WY,respectively. Under low arsenic treatment (10 mg·kg-1),more arsenic was translocated from roots to stalks and leaves,whereas no changes were found for these in other arsenic treatments. The constitution and proportion of arsenic species in different parts of the two rice varieties were similar,only non-organic arsenate and arsenite were found in roots,stalks and leaves,while in the rice grains organic arsenic,including MMA and DMA,occupied 40% of the total arsenic. We suggest planting EY rice instead of WY in mining areas in order to reduce the health risks of arsenic.