Analysis and risk assessment of arsenic in rice from different regions of Brazil

Screen for low-arsenic-risk rice varieties based on environment-genotype interactions by using GGE analysis

Arsenic (As) accumulation in rice is a global health concern that has received increased attention in recent years. In this study, 12 rice genotypes were cultivated at four As-contaminated paddy sites in Taiwan. According to the different crop seasons and As levels in the soil, the sites were further divided into 18 environmental conditions. For As in soils, results showed that 67% of the studied environments were likely to represent As contamination. For As in rice, the mean total As concentration in brown rice grains ranged from 0.17 to 0.45 mg kg-1. The analysis of variance for the environment effect indicated that grain As concentration was mainly affected by the environmental conditions, suggesting that there was a remarkable degree of variation across the trial environments. According to the combination of the GGE biplot and cumulative distribution function of order statistics (CDFOS) analysis, five genotypes-TCS17, TCS10, TT30, KH139, and TC192-were regarded as stable, low-risk genotypes because the probability of grain As concentration exceeding the maximum permissible concentration (MPC) was lower for these genotypes across all environmental conditions. Particularly, TCS17 was recommended to be the safest rice genotype. Thus, grain As levels in the selected genotypes were applied to assess the health risk to Taiwanese residents associated with As exposure through rice consumption. Results showed that the upper 75th percentile values of the hazard quotient were all less than unity. This suggested that the health risk associated with consuming the selected rice genotypes was acceptable for most of the residents. The methodology developed here would be applicable to screen for stable, low-As-risk rice genotypes across multiple field environments in other regions or countries.

Coupling phytotoxicity and human health risk assessment to refine the soil quality standard for As in farmlands

In the present study, a field experiment was conducted to investigate arsenic (As) concentrations in soils and in grains of 15 rice varieties in a contaminated site in Taiwan. The studied site was divided into two experimental units, namely plot A and plot B. The results showed that mean total As concentrations were 70.94 and 61.80 mg kg^-1 in plot A and plot B, respectively, and thus greater than or approximate to the soil quality standard for total As in Taiwan (60 mg kg^-1). The As levels in rhizosphere soil in plot A (19.71-32.33 mg kg^-1) were much higher than in plot B (6.41-8.60 mg kg^-1); however, As accumulation in brown rice did not significantly differ between the plots. These results implied that a significant variation in the bioconcentration factor (BCF) value of As existed among different rice genotypes, and a negative correlation was observed between BCF value and rhizosphere As level in the soil. In phytotoxicity, the median values of the ecological risk indicator were 104.85 and 103.89 in plot A and plot B, respectively, indicating considerable risk. In human health risk assessment, the median and 97.5%-tile values for cancer risk for both male and female residents were markedly higher than the acceptable risk (1 × 10^-4). Furthermore, non-cancer and cancer risks were higher for males than females, mainly due to the greater rice ingestion rate of males. Sensitivity analysis showed that total As concentration in soil was the main factor affecting health risks, suggesting that priority should be given to the reduction of soil As levels. To better manage the phytotoxicity of As on rice, as well as the health risk to residents resulting from exposure to As-contaminated soils, the soil quality standard for As in farmland soils should be set between 5 and 10 mg kg^-1. The methodology developed in this study could also be applied to provide the basis for refining and revising the soil quality standard for heavy metals in farmland in other regions and countries.

Assessment of cause-specific mortality and disability-adjusted life years (DALYs) induced by exposure to inorganic arsenic through drinking water and foodstuffs in Iran

The health risk and burden of disease induced by exposure to inorganic arsenic (iAs) through drinking water and foodstuffs in Iran were assessed. The iAs levels in drinking water and foodstuffs (15 food groups) in the country were determined through systematic review of three international databases (PubMed, Scopus, and Web of Science) and meta-analysis. Based on the results of the systematic review and meta-analysis, the average iAs levels in drinking water and all the food groups at the national level were lower than the maximum permissible levels. The total average non-carcinogenic risk of dietary exposure to iAs in terms of hazard index (HI) was 3.4. The average incremental lifetime cancer risk (ILCR) values of dietary exposure to iAs were determined to be 1.5 × 10^-3 for skin cancer, 1.0 × 10^-3 for lung cancer, and 4.0 × 10^-4 for bladder cancer. Over two-thirds of the non-carcinogenic and carcinogenic risk of dietary exposure to iAs was attributed to bread and cereals, drinking water, and rice. The total annual cancer incidence, deaths, disability-adjusted life years (DALYs), death rate, and DALY rate (per 100,000 people) were assessed to be 3347 (95 % uncertainty interval: 1791 to 5999), 1302 (697 to 2336), 72,606 (38,833 to 130,228), 1.6 (0.87 to 2.9), and 91 (49 to 160). The contribution of mortality in the attributable burden of disease was 95.1 %. The contributions of the causes in the attributable burden of disease were 72 % for lung cancer, 16 % for bladder cancer, and 12 % for skin cancer. Due to the significant attributable burden of disease, national and subnational action plans consisting of multi-disciplinary approaches for risk management of dietary exposure to iAs, especially for the higher arsenic-affected areas and high-risk population groups in the country are recommended.

Exposure to Inorganic Arsenic in Rice in Brazil: A Human Health Risk Assessment

In certain populations, rice is the main source of exposure to inorganic arsenic (iAs), which is associated with cancer and non-cancer effects. Although rice is a staple food in Brazil, there have been few studies about the health risks for the Brazilian population. The objective of this study was to assess the risks of exposure to iAs from white rice and brown rice in Brazil, in terms of the carcinogenic and non-carcinogenic effects, and to propose measures to mitigate those risks. The incremental lifetime cancer risk (ILCR) and hazard quotient (HQ) were calculated in a probabilistic framework. The mean ILCR was 1.5 × 10^-4 for white rice and 6.0 × 10^-6 for brown rice. The HQ for white and brown rice was under 1. The ILCR for white and brown rice was high, even though the iAs concentration in rice is below the maximum contaminant level. The risk for brown rice consumption was lower, which was not expected. Various mitigation measures discussed in this report are estimated to reduce the risk from rice consumption by 5-67%. With the support of public policies, measures to reduce these risks for the Brazilian population would have a positive impact on public health.