Chronic exposure to Arsenic (As) causes significant human health effects including various cancers. Total As concentrations from 300 polished rice samples cultivated near the mining areas in Korea were analyzed to estimate a probabilistic assessment of human health risk from As-contaminated rice. The mean of total As concentrations in rice was 0.09 mg/kg and lognormal distribution model was set for total As concentrations. Human health risk for As in rice was estimated using gender-specific rice consumption data and average daily dose (ADD). While cancer risk (CR) and hazard quotient (HQ) were calculated using oral cancer slope factor (OCSF) and Reference dose (RfD) suggested by the U.S. EPA. Mean of CR posed by total As was 2.16 (for male) and 1.83 (for female) per 10,000. The HQ for general population from rice cultivated near the mining areas in Korea was below 1 as the 50th percentile of general population. However, less than 10% of general population consuming rice cultivated near the mining areas would exceed 1.0. This result is similar with those from each gender-specific group.

Objective of this study was to investigate the difference of cadmium (Cd) levels in rice grains from non-polluted fields and to define the gene associated with Cd uptake for producing safety food. Cd was analyzed by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The average concentration of Cd in rice grains was 0.943 μg/kg and Cd levels ranged from 0.050 to 5.699 μg/kg. Genome-Wide Association study (GWAS) based on phenotype data for Cd levels was performed. However, results of GWAS were affected by subpopulation structure and caused false positive. Therefore, GWAS for rice ecotypes (temperate Japonica, tropical Japonica, Indica, Aus, Aromatic, and Admixture) was performed to minimize false positive. GWAS results showed that Os01g0611300, Os01g0611900, Os01g0611950, Os01g0612000, Os01g0612200, Os11g0444400, Os11g0444700, Os11g0444800, and Os11g0444900 genes have significant correlation with Cd levels in rice grains. The sequences of these genes were compared to sequence positions of each other gene (haplotype analysis). According to the results of haplotype analysis, Cd levels of non-synonymous group were higher than other groups and sequence of non-synonymous group was similar to that of Indica. These results were corresponding to the previous research result that Cd levels of Indica were higher than Japonica. Therefore, candidate genes detected through GWAS need to be examined by knock-out or cross breeding.

Iron is an essential mineral found in every cell of the human body to make the oxygen-carrying proteins hemoglobin and myoglobin. More than 2 billion people face Fe deficiency. Rice can be a potentially valuable source to supplement that mineral since it is staple food for two-thirds of the world’s population. To bring the nutritional level of the milled product up to that of the whole grain (brown), rice should be enriched with thiamin, niacin and iron. Thus we searched a possible allelic source from Heuristic or core rice set, which is derived from a total 24,368 rice germplasms, to increase the mineral content in rice varieties. The concentration and distribution of Fe in 137 accessions of core set of brown rice grain flour sample were determined by ICP-OES. The range of the concentration and distribution of Fe in 137 core accessions of brown rice grain were wide, from 0.088mg/L to 1.205mg/L, with mean 0.292mg/L. To examine Fe related genes, whole-genome resequencing data of 137 accessions of rice core set were analyzed by Genome Wide Associations Study (GWAS). Our result suggests that Fe determined by ICP-OES facilitates the evaluation of the differences in Fe composition for future rice breeding program