Arsenic Concentration In Rice Research Articles

Alternate wetting and drying decreases arsenic content and increases yield of rice grown in organic matter amended soil

Organic matter (OM) shows a critical role in mobilization and uptake of arsenic (As) by rice, and water management practice can mitigate this problem. However, very few research highlighted the impact of management of water on rice as influenced by OM amendment. Therefore, this study has evaluated the changes in As mobilization in paddy soil under different OM amendment and water management practices. Here, rice was grown to maturity in a two-factorial pot experiment comprising two different water management practices [continuous flooding (CF) and alternate wetting drying (AWD)] and eight combinations of As and OM amendment [comprising two As treatments (0 and 20 ppm) and four OM amendments (0, 0.25%, 0.5% and 5.0% w/w)]. Application of OM in As contaminated soil caused a significant increase in As accumulation in rice, and exhibited decreased growth and yield of rice. However, the results showed that rice growth and yield was significantly higher under AWD practice compared to CF. Arsenic concentration in rice was the lowest in As and OM control pots (44.67 µg/kg in AWD and 62.13 µg/kg in CF), and higher in As treated pots. Moreover, As concentration in rice grain increased with increasing levels of OM amendment. The As concentration in rice grain (168.44 µg/kg in AWD and 183.85 µg/kg in CF) was significantly higher in As treated pots with 0.5% OM amendment compared to other treatment combinations. Application of 5% OM in As contaminated soil did not produce any grains due to extreme toxicity. Thus, As accumulation in rice can be decreased by AWD water management technique without compromising yield. The findings suggest that applying OM in paddy soils with high soil As content should be done with caution.

Arsenic Levels in Soil and Rice and Health Risk Assessment via Rice Consumption in Industrial Areas of East Java, Indonesia

Industrial use of arsenic can potentially cause environmental problems in water, soil, and air. Arsenic is one of heavy metals that is highly toxic and carcinogenic. Arsenic contamination in the environment is harmful to human health because it can enter the body through the food chain. This study determined the concentration of arsenic in soil and rice and its impact on human health risks. Sampling was carried out in several East Java industrial cities or districts, for instance, Gresik, Mojokerto, Sidoarjo, Nganjuk, Ponorogo, and Surabaya. The measurement of arsenic in soil was done using Energy Dispersive X-Ray fluorescence (EDXRF), while the measurement of arsenic in rice was done by Total X-Ray Fluorescence (TXRF). The results showed that arsenic concentration in several areas of East Java has varying levels. The concentration of arsenic in soil was highest in Gresik (13,786 mg/kg). The highest arsenic concentration in rice was found in Mojokerto (0.154 mg/kg). The results of risk assessment in this study showed that the Hazard Quotient (HQ) value was >1 and the Excess Cancer Risk (ECR) was >10-4 in all areas at the age of children <2 years. Health risk assessment of adults showed HQ>1 and ECR>10-4 in several areas of East Java. This indicates that consumption of rice contaminated with arsenic has the potential to pose non-carcinogenic and carcinogenic health risks.

Mitigating effect of various phosphorus sources on arsenic toxicity in anaerobic conditions for rice and aerobic conditions for sunflower and maize plants

Arsenic (As) contamination is one of the major factors that contribute to environmental pollution and it plays havoc with sustainability of crop production. Nano-hydroxyapatite (nHAP) can be an effective phosphorus (P) source to cope with As toxicity. The mitigating effects of variable P sources on As toxicity in rice, sunflower and maize grown in alkaline soil were evaluated. Arsenic was applied at 0 and 20 mg kg-1 and P was applied at 0, 50 and 500 mg kg-1 in the form of Triple Super Phosphate (TSP) and nHAP. In addition, the same amount of phosphoric acid (PA) was also used in sunflower and maize experiments with the other P sources. The structural and functional properties of nHAP were determined by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-Ray Spectroscopy (EDX). Stunted growth was observed in rice, and less in sunflower; maize remained unaffected by As toxicity. In the presence of As, a high dose of TSP (TSP500) and nHAP (nHAP500) significantly increased dry weights of rice plants compared with control plants. Arsenic concentrations in rice were decreased by about 25% in the presence of 50 mg kg-1 TSP (TSP50) and nHAP500 treatments. Phosphorus treatments had no significant effect on the As concentrations of sunflower, while in maize plants As levels increased with TSP500 treatment as compared with P0As0. In the absence of As, TSP500 and nHAP500 treatments significantly increased rice P concentration (2.80 and 2.27 g kg-1) whereas, in the presence of As, TSP500 significantly increased P concentration in rice plants as compared with P0. Arsenic had no significant effect on sunflower P concentration while the maize P concentration was decreased in the P0 treatment. It can be concluded that TSP and nHAP were effective in alleviating As toxicity in rice and sunflower. Comparative studies are further needed to determine the long-term effects of TSP and nHAP on prevention of As toxicity in field conditions.

Influence of Mining Activities on Arsenic Concentration in Rice in Asia: A Review

Crop and livestock farming on contaminated soil has been found to induce the accumulation of trace elements in edible parts of plants, with subsequent risk to human and animal health. Since rice crop is a major source of energy in worldwide diets and is consumed by more than 3 billion people, the soil–rice pathway is regarded as a prominent route of human exposure to potentially toxic elements. This study provides an overview of arsenic contamination in paddy rice from mining-impacted areas in several Asian countries that are primary rice consumers. From this review, it may be concluded that mining activities, along with the associated residual waste, significantly contribute to arsenic contamination of this food crop as rice samples from these regions were highly contaminated, with the highest total arsenic concentrations recorded being 3–4 times higher than the maximum levels proposed by the Codex Alimentarius Commission. While the contamination in China, Korea, Indonesia, and Thailand appeared to be slightly affected by mining activities, the elevated levels of arsenic in rice from mining areas in India, Bangladesh, and Vietnam could be derived from arsenic-contaminated groundwater.

Water Management and Varietal Selection Approach in Mitigation of Arsenic in Inceptisols of West Bengal, India

ABSTRACT Irrigation with contaminated Arsenic (As) water is greatly correlated with increased soil As along with enhanced uptake in plants, which in turn biologically accumulates in different parts of the plant at toxic levels. The current study is aimed at characterization and mitigation of Arsenic contamination through irrigation and varietal selection. Characterization of arsenic was done through staggered random sampling. Experimental plots were laid in highly As contaminated farmer’s field with three rice varieties and three moisture regime in randomized block design keeping summer rice as standing crop. According to the Artificial Neural Network (ANN) study, soil phosphorus, followed by soil pH, Nitrogen, and Potassium have been found to be more sensitive in regulating soil As. The Alternate Wetting Drying (AWD) irrigation regime has significantly less arsenic concentration in rice when compared with Saturation (SAT)<Continuous Submergence (CS). Interestingly, maximum transfer of arsenic from soil to grain has been observed in AWD, with the least use of contaminated irrigation. Transfer factors (TFs) for As was least in cultivar IET-17430 as compared with IR-36> IET-4786.

Arsenic speciation and elemental composition of rice samples from the Slovenian market

A survey of highly toxic arsenic compounds, together with some other elements was carried out on 40 polished rice samples (white, basmati and parboiled) and 10 brown rice samples from the Slovenian market. The average total As concentration was 157 ± 60 μg kg−1; highest levels were found in parboiled and brown rice and lowest in basmati. The average inorganic As concentration was 90 ± 35 μg kg−1. Dimethylarsinic acid and monomethylarsonic acid, which also exhibit high toxicity levels in some cases constitute >50% of total arsenic and might deserve more attention. Contrary to other foods, the total arsenic concentration in rice may even be a better health hazard indicator than the inorganic arsenic concentration. Elemental analysis of rice revealed large differences between polished and brown rice, especially for Mg, Mn, P, Fe and K, which were 2–4 times higher in brown rice than in polished rice.

Effect of cooking on arsenic concentration in rice.

This study assessed the effect of rinsing and boiling on total content of As (tAs) and of its inorganic and organic forms in different types of rice (polished and brown) from Spain and Ecuador. Rice was subjected to five different treatments. The results showed that the treatment consisting of three grain rinsing cycles followed by boiling in excess water showed a significant decrease in tAs content compared with raw rice. Regarding As species, it is worth noting that the different treatments significantly reduced the content of the most toxic forms of As. The estimated lifetime health risks indicate that pre-rinsing alone can reduce the risk by 50%, while combining it with discarding excess water can reduce the risk by 83%; therefore, the latter would be the preferable method.

Genotypic differences in shoot silicon concentration and the impact on grain arsenic concentration in rice

AbstractSilicon in rice (Oryza sativa L.) has been demonstrated to be involved in resistance to lodging, drought, and salinity, and also enhances resistance to pests and diseases. The aim of this study was to determine the range of silicon concentration in a set of rice (Oryza sativa L.) accessions, and to determine if the natural variation of shoot silicon is linked to the previously identified silicon transporters (Lsi genes). Silicon concentration was determined in 50 field‐grown accessions, representing all sub‐populations of rice, with all accessions being genotyped with 700K SNPs. SNPs within 10 kb of the Lsi genes were examined to determine if any were significantly linked with the phenotypic variation. An XRF method of silicon determination compared favourably with digestion and colorimetric analysis. There were significant genotypic differences in shoot silicon ranging from 16.5 to 42.4 mg g−1 of plant dry weight, but there was no significant difference between the rice sub‐populations. Plants with different alleles for SNPs representing Lsi2 and Lsi3 were significantly different for shoot silicon concentration. Shoot silicon correlated negatively with grain arsenic in the tropical and temperate japonica sub‐population, suggesting that accessions with high shoot silicon have reduced grain arsenic. This study indicates that alleles for Lsi genes are excellent candidate genes for further study to explain the natural variation of shoot silicon in rice.

Effects of Arsenic, Iron and Fertilizers in Soil on Rice in Cambodia.

Background.In parts of Cambodia, irrigation with groundwater results in arsenic accumulation in soils and rice, leading to health concerns associated with rice consumption. A high concentration of iron in groundwater can precipitate arsenic and reduce its bioavailability, however high concentrations of arsenic and iron can also reduce rice production. Furthermore, concerns have been raised about chemical contamination from inorganic fertilizers used to grow rice. The relationship between soil geochemistry and arsenic concentrations in rice is not yet fully understood.Objectives.The primary objective of this project was to investigate the relationship between arsenic concentrations in irrigation water, soil and rice collected from different sites in Cambodia. A secondary objective was to explore arsenic and phosphorus levels in fertilizer samples obtained from the study area in Cambodia.Methods.The present study collected 61 well water samples, 105 rice samples, 70 soil samples, 11 inorganic fertilizer samples and conducted interviews with 44 families along the Mekong River in Cambodia. Analyses for metals, total arsenic, and arsenic species in the water and rice were conducted in Canada by inductively coupled plasma mass spectrometry. Analyses for metals, total arsenic and phosphorus in soils and inorganic fertilizers were conducted in Cambodia and Singapore by X-ray fluorescence.Results.The concentration of arsenic in rice paddy soils was highly variable and as much as 20 times higher near the irrigation wells than in more distal areas of the paddy. Two farmers in Preak Russey had integrated soil samples with arsenic levels above the concentration associated with toxicity to rice in Taiwan (40 mg/kg) and above the Dutch concentration requiring intervention or remediation (55 mg/kg). The highest total arsenic measured in soil was 95 mg/kg. In Preak Russey, the loading of arsenic from irrigation water was 3710 times greater than the loading of arsenic from inorganic fertilizers. Half of the commercial inorganic fertilizers had less than 50% of the labelled content of phosphorus.Conclusions.Emphasis should be placed on improving the management of irrigation water, not on inactivation of arsenic in soil. The high levels of iron in groundwater mitigate arsenic toxicity, but the accumulation of iron could later result in lower rice productivity. Irrigation of rice with groundwater is not likely sustainable. To improve rice productivity, the content of phosphorus in local inorganic fertilizers must be improved to world standards. X-ray fluorescence analysis can quickly identify poor quality fertilizers.Informed Consent. ObtainedCompeting Interests.The authors declare no competing financial interests

Groundwater Irrigation and Arsenic Speciation in Rice in Cambodia.

Background.Arsenic bioaccumulation in rice is a global concern affecting food security and public health.Objective.The present study examined arsenic species in rice in Cambodia to characterize health risks with rice consumption and to clarify uncertainties with Codex guidelines.Methods.The present study collected 61 well water samples, 105 rice samples, 70 soil samples, and conducted interviews with 44 families in Preak Russey near the Bassac River and Kandal Province along the Mekong River in Cambodia. Analyses of metals, total arsenic and arsenic species were conducted in laboratories in Canada, Cambodia and Singapore.Results.Unlike in Bangladesh, rice with the highest total arsenic concentrations in Cambodia contains mostly organic arsenic, dimethylarsinic acid (DMA), which is unregulated and much less toxic than inorganic arsenic. The present study found that storing surface runoff in ditches prior to irrigation can significantly reduce the arsenic concentration in rice. It is possible to remove > 95% of arsenic from groundwater prior to irrigation with natural reactions.Conclusions.The provision of high quality drinking water in 2015 to Preak Russey removed about 95% of the dietary inorganic arsenic exposure. The extremes in arsenic toxicity that are still obvious in these farmers should become less common. Rice from the site with the highest documented levels of arsenic in soils and water in Cambodia passes current Codex guidelines for arsenic.Informed Consent.ObtainedCompeting Interests.The authors declare no competing financial interests.

Effects of compost amended lead–arsenate contaminated soils on total and inorganic arsenic concentrations in rice

ABSTRACTRice (Oryza sativa L.), a staple crop for over 50% of the world's population, is also a source of dietary arsenic (As) because of it's efficiencyat accumulating As. Lead–arsenate pesticide was used in agriculture, these soils potentially may be used for rice production. The objective of this study was to determine the effects of compost on total and inorganic As concentrations in rice grown on lead–arsenate contaminated soils. Three lead–arsenatesoils were amended with 10% by weight of compost and planted with rice under flooded and non-flooded conditions. Rice grain yieldwas higher with compost but not flooding. Flooding significantly increased total and inorganic As concentrations. In most cases, rice inorganic Asconcentrations were higher than the limit set by Chinaat 0.2 mg kg−1. Compost at therate used did not reduce rice grain As to safe levels.Lead–arsenate contaminated soils are not recommended for rice production.

Arsenic uptake, accumulation and toxicity in rice plants: Possible remedies for its detoxification: A review.

Arsenic (As) is a toxic metalloid. Serious concerns have been raised in literature owing to its potential toxicity towards living beings. The metalloid causes various water- and food-borne diseases. Among food crops, rice contains the highest concentrations of As. Consuming As-contaminated rice results in serious health issues. Arsenic concentration in rice is governed by various factors in the rhizosphere such as availability and concentration of various mineral nutrients (iron, phosphate, sulfur and silicon) in soil solution, soil oxidation/reduction status, inter-conversion between organic and inorganic As compounds. Agronomic and civil engineering methods can be adopted to decrease As accumulation in rice. Agronomic methods such as improving soil porosity/aeration by irrigation management or creating the conditions favorable for As-precipitate formation, and decreasing As uptake and translocation by adding a inorganic nutrients that compete with As are easy and cost effective techniques at field scale. This review focuses on the factors regulating and competing As in soil-plant system and As accumulation in rice grains. Therefore, it is suggested that judicious use of water, management of soil, antagonistic effects of various inorganic plant-nutrients to As should be considered in rice cultivated areas to mitigate the building up of As in human food chain and with minimum negative impact to the environment.

Arsenic speciation in locally grown rice grains from Hunan Province, China: Spatial distribution and potential health risk

Arsenic contaminations have been evaluated in rice grains from Hunan Province, China. Forty-three locally grown rice samples were collected from 40 counties. Arsenic species including As(III), As(V), MMA and DMA were separated and determined by HPLC-ICP-MS method. The mean concentration of total arsenic in rice samples was 129.4±49.2μg/kg, lower than the Chinese maximum contaminant levels of inorganic arsenic in rice (200μg/kg). The dominant species detected in rice samples was As(III), following DMA, As(V) and MMA. The Pearson's correlation analysis indicated significant positive relationships between As(III) and total arsenic (r=0.939, p<0.01), and DMA and total arsenic (r=0.761, p<0.01). However, the percentage of As(III) decreased with the total arsenic concentration in rice (r=−0.515, p<0.01). Spatial distribution map of total arsenic concentration in rice samples from Hunan Province was obtained using kriging interpolation. High levels of total arsenic in rice grains were observed in south and east regions associated with mining activities and urbanization process. The cancer risk and hazard quotient were employed to estimate the potential human health risk. The results suggested great carcinogenic risk and high potential non-carcinogenic risk to people consuming local rice in Hunan Province.

Arsenic concentration in rice, fish, meat and vegetables in Cambodia: a preliminary risk assessment

To assess arsenic contaminations and its possible adverse health effects, food samples were collected from Kandal, Kratie and Kampong Cham in Cambodia. The highest and the lowest concentrations were observed in fish (mean 2,832 ng g(-1), ww) collected from Kandal province and cattle stomach (1.86 ± 1.10 ng g(-1), ww) collected from Kratie, respectively. The daily intake of arsenic via food consumption was 604, 9.70 and 136 μg day(-1) in Kandal, Kratie and Kampong Cham, respectively. The arsenic dietary intake in Kandal ranked No. 1 among all the 17 compared countries or regions. Fish consumption contributed the greatest proportion of total arsenic daily intake in Kandal (about 63.0 %) and Kampong Cham (about 69.8 %). It is revealed to be a much more important exposure pathway than drinking water for residents in Kampong Cham. The results of risk assessment suggested that the residents in Cambodia, particularly for people in Kandal province, suffer high public health risks due to consuming arsenic-contaminated food.

Silicate Mineral Impacts on the Uptake and Storage of Arsenic and Plant Nutrients in Rice (Oryza sativa L.)

Arsenic-contaminated rice grain may threaten human health globally. Since H₃AsO₃⁰ is the predominant As species found in paddy pore-waters, and H₄SiO₄⁰ and H₃AsO₃⁰ share an uptake pathway, silica amendments have been proposed to decrease As uptake and consequent As concentrations in grains. Here, we evaluated the impact of two silicate mineral additions differing in solubility (+Si(L), diatomaceous earth, 0.29 mM Si; +Si(H), Si-gel, 1.1 mM Si) to soils differing in mineralogy on arsenic concentration in rice. The +Si(L) addition either did not change or decreased As concentration in pore-water but did not change or increased grain-As levels relative to the (+As--Si) control. The +Si(H) addition increased As in pore-water, but it significantly decreased grain-As relative to the (+As--Si) control. Only the +Si(H) addition resulted in significant increases in straw- and husk-Si. Total grain- and straw-As was negatively correlated with pore-water Si, and the relationship differed between two soils exhibiting different mineralogy. These differing results are a consequence of competition between H₄SiO₄⁰ and H₃AsO₃⁰ for adsorption sites on soil solids and subsequent plant-uptake, and illustrate the importance of Si mineralogy on arsenic uptake.

Bioaccessibility of arsenic in various types of rice in an in vitro gastrointestinal fluid system

Rice can be a major contributor to dietary arsenic exposure because of the relatively high total arsenic concentration compared to other grains, especially for people whose main staple is rice. This study employed in vitro gastrointestinal fluid digestion to determine bioaccessible or gastrointestinal fluid extractable arsenic concentration in rice. Thirty-one rice samples, of which 60 % were grown in the United States, were purchased from food stores in New York City. Total arsenic concentrations in these samples ranged from 0.090 ± 0.004 to 0.85 ± 0.03 mg/kg with a mean value of 0.275 ± 0.161 mg/kg (n = 31). Rice samples with relatively high total arsenic (>0.20 mg/kg, n = 18) were treated by in vitro artificial gastrointestinal fluid digestion, and the extractable arsenic ranged from 53 % to 102 %. The bioaccessibility of arsenic in rice decreases in the general order of extra long grain, long grain, long grain parboiled, to brown rices.

Inorganic arsenic and trace elements in Ghanaian grain staples

A total of 549 samples of rice, maize, wheat, sorghum and millet were obtained from markets in Ghana, the EU, US and Asia. Analysis of the samples, originating from 21 countries in 5 continents, helped to establish global mean trace element concentrations in grains; thus placing the Ghanaian data within a global context. Ghanaian rice was generally low in potentially toxic elements, but high in essential nutrient elements. Arsenic concentrations in rice from US (0.22 mg/kg) and Thailand (0.15 mg/kg) were higher than in Ghanaian rice (0.11 mg/kg). Percentage inorganic arsenic content of the latter (83%) was, however, higher than for US (42%) and Thai rice (67%). Total arsenic concentration in Ghanaian maize, sorghum and millet samples (0.01 mg/kg) was an order of magnitude lower than in Ghanaian rice, indicating that a shift from rice-centric to multigrain diets could help reduce health risks posed by dietary exposure to inorganic As.

Effect of rice-cooking water to the daily arsenic intake in Bangladesh: results of field surveys and rice-cooking experiments

The effect of rice-cooking water to the daily arsenic intake of Bangladeshi people was investigated. At the first field survey, uncooked rice and cooked rice of 29 families were collected. Their arsenic concentrations were 0.22+/-0.11 and 0.26+/-0.15 mg/kg dry wt, respectively. In 15 families, arsenic concentration in rice increased after cooking. Good correlation (R(2)=0.89) was observed between arsenic in rice-cooking water and the difference of arsenic concentration in rice by cooking. In the second survey, we collected one-day duplicated food of 18 families. As a result, we estimated that six of 18 families likely used the arsenic contaminated water for cooking rice even they drank less arsenic-contaminated water for drinking purpose. We also conducted rice-cooking experiments in the laboratory, changing arsenic concentration in rice-cooking water. Clear linear relationships were obtained between the arsenic in rice-cooking water and the difference of arsenic concentration in rice by cooking. Factors that affect arsenic concentration in cooked rice are suggested as follows: (1) arsenic concentration in uncooked rice, (2) that in rice-cooking water, (3) difference in water content of rice before and after cooking, and (4) types of rice, especially, the difference between parboiled and non-parboiled rice.

Effect of two different rice dehusking procedures on total arsenic concentration in rice

Pollution of subterranean water by arsenic (As) in Asia has resulted in the worst chemical disaster in human history. For populations living on subsistence rice diets, As contamination of rice grain contributes greatly to dietary As exposure. The main objectives of this study were to compare two dehusking processes: (a) wet process (soaking of rice, boiling and mechanical hulling) and (b) dry process (mechanical hulling), and recommend the method leading to a lower As content in commercial rice. In general, hulling of paddy rice (373 μg As kg−1) significantly decreased As content in rice grain (311 μg As kg−1). The final As concentrations in boiled rice (final product of the wet process) and atab rice (dry process) were 332 and 290 μg kg−1. Thus, the dry method is recommended for dehusking paddy rice if not As-free water is available. However, villagers can reduce the As content in the wet system by discarding the soaking water and using new water for the light boiling. Finally, it is not recommended to use rice husk for feeding animals because the As concentration is very high, approximately 1,000 μg As kg−1.

Arsenic concentrations in rice, vegetables, and fish in Bangladesh: a preliminary study

Arsenic contaminating groundwater in Bangladesh is one of the largest environmental health hazards in the world. Because of the potential risk to human health through consumption of agricultural produce grown in fields irrigated with arsenic contaminated water, we have determined the level of contamination in 100 samples of crop, vegetables and fresh water fish collected from three different regions in Bangladesh. Arsenic concentrations were determined by hydride generation atomic absorption spectrophotometry. All 11 samples of water and 18 samples of soil exceeded the expected limits of arsenic. No samples of rice grain ( Oryza sativa L.) had arsenic concentrations more than the recommended limit of 1.0 mg/kg. However, rice plants, especially the roots had a significantly higher concentration of arsenic (2.4 mg/kg) compared to stem (0.73 mg/kg) and rice grains (0.14 mg/kg). Arsenic contents of vegetables varied; those exceeding the food safety limits included Kachu sak ( Colocasia antiquorum) (0.09–3.99 mg/kg, n=9), potatoes ( Solanum tuberisum) (0.07–1.36 mg/kg, n=5), and Kalmi sak ( Ipomoea reptoms) (0.1–1.53 mg/kg, n=6). Lata fish ( Ophicephalus punctatus) did not contain unacceptable levels of arsenic. These results indicate that arsenic contaminates some food items in Bangladesh. Further studies with larger samples are needed to demonstrate the extent of arsenic contamination of food in Bangladesh.