A study on toxic and essential elements in rice from the Republic of Kazakhstan: comparing the level of contamination in rice from the European Community

ICP-OES analysis of total As and Cd in Columbian Oryza sativa L. rice

Arsenic (As) and cadmium (Cd) are considered toxic elements, even at trace levels. Their accurate quantification in crops can be complex at low levels and due to interference with other elements. The aim of this work was to develop and validate an analytical method for As and Cd quantification in rice stem and grains from the production systems "Irrigated Rice Ecosystems" (IRE) and "Rainfed Rice Ecosystems" (RRE) in Colombia. Mineralisation was carried out by acid digestion using an open system with a heating plate. Metal detection was performed by inductively coupled plasma optical emission spectrometry (ICP-OES). Method adjustment, calibration, and validation were performed in accordance with AOAC standards, considering sensitivity, precision, accuracy, and selectivity parameters. The obtained method was applied to quantify levels in 259 rice stem and 443 grain samples from IRE and RRE.

Characterisation of a low methane emission rice cultivar suitable for cultivation in high latitude light and temperature conditions

Rice cultivation on paddy soil is commonly associated with emissions of methane, a greenhouse gas, but rice varieties may differ in their actual level of emissions. This study analysed methane emissions associated with 22 distinct rice genotypes, using gas chromatography, and identified the cultivar Heijing 5 from northern China as a potential low-methane rice variety. To confirm this and to examine whether Heijing 5 can perform similarly at higher latitudes, Heijing 5 was cultivated in field trials in China (lat. 32° N) and Sweden (lat. 59° N) where (i) methane emissions were measured, (ii) methanogen abundance in the rhizosphere was determined using quantitative PCR, and (iii) the concentrations of nutrients in water and of heavy metals in rice grain and paddy soil were analysed. The results demonstrated that the low-methane rice cultivar Heijing 5 can successfully complete an entire growth period at high-latitude locations such as central Sweden. Massively parallel sequencing of mRNAs identified candidate genes involved in day length and cold acclimatisation. Cultivation of Heijing 5 in central Sweden was also associated with relatively low heavy metal accumulation in rice grains and lowered nutrient losses to neighbouring water bodies.

A review on arsenic in the environment: bio-accumulation, remediation, and disposal

Arsenic is a widespread serious environmental pollutant as a food chain contaminant and non-threshold carcinogen. Arsenic transfer through the crops-soil-water system and animals is one of the most important pathways of human exposure and a measure of phytoremediation. Exposure occurs primarily from the consumption of contaminated water and foods. Various chemical technologies are utilized for As removal from contaminated water and soil, but they are very costly and difficult for large-scale cleaning of water and soil. In contrast, phytoremediation utilizes green plants to remove As from a contaminated environment. A large number of terrestrial and aquatic weed flora have been identified so far for their hyper metal removal capacity. In the panorama presented herein, the latest state of the art on methods of bioaccumulation, transfer mechanism of As through plants and animals, and remediation that encompass the use of physicochemical and biological processes, i.e., microbes, mosses, lichens, ferns, algae, and macrophytes have been assessed. Since these bioremediation approaches for the clean-up of this contaminant are still at the initial experimental stages, some have not been recognized at full scale. Nonetheless, extensive research on these primitive plants as bio-accumulators can be instrumental in controlling arsenic exposure and rehabilitation and may result in major progress to solve the problem on a worldwide scale.

Genetic studies for grain quality traits and correlation analysis of mineral element contents on Al-Ahsa rice and some different varieties (Oryza Sativa L.)

One of the most significant goals in plant breeding programs is to generate new rice varieties with increased elements and good grain quality. In this experiment, ten rice genotypes were evaluated for grain quality traits and protein percentage. Also, milled rice of the ten genotypes were used for analysis of mineral elements. The results revealed that mean squares attributable to genotypes were significant for all traits during the two growing seasons, showing the presence of broad genetic variability among genotypes for all traits under consideration. However, the Indica type (Egyptian Yasmin and Giza 182) gave the highest value for grain length (7.10, 6.52 mm) and grain shape (2.87, 2.82 mm) under the two seasons. While, Al-Ahsa Type1 and Al-Ahsa Type2 rice varieties gave the highest values in protein percentage, which gave 10.80 and 9.80%. Correlation coefficients among the nine grain quality traits clarifying eight absolute positive correlation grain length with grain shape, grain width with hulling % and head rice %; grain shape with amylose content %; hulling % with milled rice and head rice %; milled rice % with head rice %; head rice % with gelatinization temperature. On the other hand, there were seven absolute negative correlations between grain length with grain width; grain width with grain shape and amylose content %; grain shape with hulling % and head rice %; amylose content % with milled rice %, head rice % and gelatinization temperature. In micronutrient elements Al-Ahsa Type1 and Al-Ahsa Type2 varieties gave the heights value for N, P, K, Mg %. Also, gave the heights value for Na (73.25, 73), Fe (20.12, 19.80), and Zn (125.60, 122.70). Pearson’s correlation observed eight absolute positive and significant correlations, which were between; nitrogen content (N), P, K, Mg, Na, Fe, Zn, Cu and protein percentage.

Arsenic contamination, impact and mitigation strategies in rice agro-environment: An inclusive insight

Arsenic (As) contamination and its adverse consequences on rice agroecosystem are well known. Rice has the credit to feed more than 50% of the world population but concurrently, rice accumulates a substantial amount of As, thereby compromising food security. The gravity of the situation lays in the fact that the population in theAs uncontaminated areas may be accidentally exposed to toxic levels of As from rice consumption. In this review, we are trying to summarize the documents on the impact of As contamination and phytotoxicity in past two decades. The unique feature of this attempt is wide spectrum coverages of topics, and that makes it truly an interdisciplinary review. Aprat from the behaviour of As in rice field soil, we have documented the cellular and molecular response of rice plant upon exposure to As. The potential of various mitigation strategies with particular emphasis on using biochar, seed priming technology, irrigation management, transgenic variety development and other agronomic methods have been critically explored. The review attempts to give a comprehensive and multidiciplinary insight into the behaviour of As in Paddy -Water - Soil - Plate prospective from molecular to post-harvest phase. From the comprehensive literature review, we may conclude that considerable emphasis on rice grain, nutritional and anti-nutritional components, and grain quality traits under arsenic stress condition is yet to be given. Besides these, some emerging mitigation options like seed priming technology, adoption of nanotechnological strategies, applications of biochar should be fortified in large scale without interfering with the proper use of biodiversity.

Evaluation of environmental contamination by toxic trace elements in Kazakhstan based on reviews of available scientific data

The environmental situation concerning pollution by (eco)toxic and persistent trace elements in Kazakhstan has been investigated by analytical reviews of scientific studies published over the past 20 years reporting concentrations of 10 toxic trace elements (TTE) observed in soil, sediments, or surface water. A database of 62 articles published in Kazakh, Russian, or English covered the majority of the territory of the country for soil and water samples but to a lesser extent for sediments. Reported concentrations were summarized using statistical parameters, then spatialized and finally classified in contamination classes according to local legislation. This analysis revealed some hotspots of TTE in surface waters (Cd and Pb), soil (As), and sediments (Cd and As). Hotspots of less toxic Cu, Zn, and Mn were also detected. Spatialization of results allowed localization of these hotspots close to industrial sites, such as smelters or mining and metallurgic combines. Others have been shown to be close to disused mining sites or landfills with municipal waste. Methodological improvements for further studies have been suggested, such as to integrate more West Kazakhstan or remote areas in sampling campaigns, but also to describe more exhaustively the used analytical methods and to be more attentive to the speciation of the analyzed form of the element. Finally, a management strategy to strengthen a sustainable food policy has been proposed: to reduce emissions by modernization of industrial facilities and better waste management, to organize land use depending on the contamination levels, and to reduce the bioavailability of the toxic elements.

Arsenic bioaccessibility in rice grains via modified physiologically-based extraction test (MPBET): Correlation with mineral elements and comparison with As relative bioavailability

Rice consumption is a major dietary source of human exposure to arsenic (As), with As bioavailability being an important factor influencing its health risk. In this study, the As bioaccessibility was measured in 11 rice grains (140-335 μg As kg^-1), which were compared to As relative bioavailability previously measured based on a mouse bioassay (Li et al., 2017). Using modified physiologically-based extraction test for rice (MPBET), As bioaccessibility in raw rice samples (44-88% in the gastric phase and 47-102% in the intestinal phase) was similar to those in cooked rice (42-73% and 43-99%). Arsenic bioaccessibility in rice was generally higher in the intestinal phase than in the gastric phase, with Fe and Ca concentrations in rice being negatively correlated with As bioaccessibility in the gastric phase (R² = 0.47-0.49). In addition, for cooked rice, strong positive correlation was observed between bioaccessible As and inorganic As (R² = 0.63-0.72), suggesting inorganic As in rice was easier to dissolve than organic As in gastrointestinal digestive fluids. Due to limited variation in As bioaccessibility and As bioavailability among the 11 samples, a weak correlation was observed between them (R² = 0.01-0.03); however, As bioaccessibility values measured by the gastric phase (GP) of the MPBET agreed with As bioavailability values based on a mouse bioassay, suggesting the potential of the MPBET_GP to predict As bioavailability in rice. Future work is needed to ascertain the robustness of the MPBET_GP in predicting As bioavailability in rice using additional samples.

Identifying the Food Sources of Selected Minerals for the Adult European Population among Rice and Rice Products

The problem of dietary deficiency of several essential elements among different stages of life is still observed. The consumption of whole grains (among others unprocessed rice) is recommended as a part of a healthy diet. This research aimed to determine the content of selected macro- and microelements in rice and rice products to verify whether the tested products could be regarded as a source of selected minerals in the diet of the adult European population.

METHODS

A total of 99 samples from 12 groups of rice products (basmati, black, brown, parboiled, red, wild, white rice and expanded rice, rice flakes, flour, pasta, and waffles) were obtained. The atomic absorption spectrometry method (AAS) was used to determine the content of Ca, Cu, Fe, Mg, Mn, Se and Zn in the study material.

RESULTS

The average measured contents of Ca, Cu, Fe, Mg, Mn, Se and Zn were as follows: 226.3 ± 160.6 mg/kg, 3.6 ± 2.8 mg/kg, 9.4 ± 7.0 mg/kg, 618.0 ± 498.4 mg/kg, 16.7 ± 10.0 mg/kg, 242.9 ± 140.4 µg/kg and 19.5 ± 15.0 mg/kg, respectively. Statistical analyses confirmed the differences in the levels of the studied elements between the subgroups of processed and unprocessed products. Considering the tolerable upper intake level of studied elements, the tested products could be regarded as safe to consume.

CONCLUSION

All tested products can be recommended as a source of Cu, Mn, and Se, while a majority of studied products can be considered a source of Mg and Zn in the diet of the adult European population.

Probabilistic assessment of the daily intake of microelements and toxic elements via the consumption of rice with different degrees of polishing

BACKGROUND

The polishing process plays a key role in determining the beneficial quality of rice. However, the effects of polishing on human exposure to essential and toxic elements are not well reported. This study evaluated the effects of polishing on the levels of essential and toxic elements in rice grains and evaluated the status of their daily intake using probabilistic assessment.

RESULTS

The levels of essential elements decreased as the degree of polishing increased. The highest reduction percentages of essential elements [24% of copper (Cu), 26% of nickel (Ni), and 52% of manganese (Mn)] were found after the first polishing step. The highest zinc (Zn) reduction (15%) was found after the fourth polishing step. For toxic elements, polishing significantly reduced the arsenic (As) concentration (15-31%) from that of the whole grains, of which 26% was removed after the first step.

CONCLUSION

Polishing removed both essential and toxic elements from rice grains. The highest losses of Cu, Mn, Ni, and As were found after the first polishing step since these elements generally localize in the aleurone layers of rice grains. The last polishing step caused a significant Zn reduction from the grain. Polishing had no significant effect on the cadmium (Cd) concentration in grains. The consumption of all types of rice could not supply sufficient amounts of all microelements except Mn to maintain optimum health. Both As and Cd intake levels were lower than the benchmarks of toxic health effects. Thus, the potential health impacts of both of these elements in rice can be neglected. © 2020 Society of Chemical Industry.

Arsenic in rice and rice products in Northwestern Mexico and health risk assessment

The aim of this study was to evaluate the health risk of arsenic exposure by consumption of rice and its products marketed in northwestern Mexico. Sixty-six national and imported rice products were purchased in markets in northwestern Mexico, an endemic arsenic region. Total and inorganic arsenic in rice samples were analysed by inductively coupled plasma atomic emission spectroscopy and the risk assessment was evaluated according to the hazard quotient (HQ) and carcinogenic risk (CR). Total and inorganic arsenic in rice samples ranged from 0.06 to 0.29 mg/kg and from 0.03 to 0.13 mg/kg, respectively, and 40% of the analysed samples exceeded FAO/WHO arsenic recommended levels. The inorganic/total arsenic ratio ranged from 15% to 65%. The HQ and CR values for total and inorganic arsenic did not exceed safety levels. Therefore, rice supply in the northwestern of Mexico appears to be safe for human consumption.

Pollution with trace elements and rare-earth metals in the lower course of Syr Darya River and Small Aral Sea, Kazakhstan

Over recent decades the Aral Sea has faced a major human-driven regression leading to environmental, economic and health impacts. Previous research has indicated that its region may be highly polluted yet there is little recent data to assess the scale or nature of the pollution. The present study investigated the concentration of elements for which the World Health Organization (WHO) has established guideline levels (Al, As, B, Ba, Cd, Cr, Cu, Ni, Pb, Sb) as well as 16 rare-earth elements (Ce, Eu, Er, Gd, La, Nd, Pr, Sc, Sm, Dy, Ho, Lu, Tb, Tm, Y, Yb) in the Small Aral Sea (SAS) and its inflow, the Syr Darya River (SDR). The latter displayed increased levels of Al (mean 851 μg L^-1), As (35.8 μg L^-1), Cd (2.8 μg L^-1), Pb (10.1 μg L^-1) and U (4.9 μg L^-1), exceeding the guideline limits at selected sites. In the SAS these limits were exceeded at certain locations in the case of As and U. The total mean concentration of REEs in the SDR and SAS amounted to 22.6 and 61.7 μg L^-1, respectively, with Pr, Ce and Nd constituting the greatest share. The concentrations of B, Ba Cr, Cu, Se and Ni were below the WHO guideline levels at all studied sites while Sb and Hg were always below detection limits. This research provides an updated status on the levels of contamination of the surface waters in the ecological disaster zone of the Aral Sea in Kazakhstan.

Toxic metals (As and Pb) in Sargassum elegans Suhr (1840) and its bioactive compounds

Sargassum elegans Suhr 1840 (Phaeophyta) is a brown marine macro alga, which is used both nutritionally and medicinally in the coastal areas of Southern Africa. Consequently, we conducted a phytochemical and analytical investigation on samples of this species collected from seven sites along the coast of KwaZulu-Natal, South Africa. Sargassum elegans was found to be rich in β-sitosterol, fucosterol and phaeophytin a as confirmed by spectroscopic techniques. Concentrations of essential and toxic elements varied significantly with location and were in the order of Ca > Mg> Fe > As > Cu > Zn > Mn > Ni > Pb > Co > Se > Cr > Cd. The accumulation of As by S. elegans was also evident as concentrations ranged from 42 to 105 mg kg-1, of which, 21 to 53 mg kg-1 was in inorganic form; consumption of this species may therefore increase dietary exposure to inorganic arsenic. Abbreviation: CRM: Certified reference material; NMR: Nuclear magnetic resonance; ICP - OES: Inductively coupled plasma - optical emission spectroscopy; PCA: Principal component analysis.

Distribution of nutrient and toxic elements in brown and polished rice

Rice is a staple food in many countries around the world and it is a source of not only the nutrients, but also toxic elements. In this study, we evaluated four degrees of polishing and determined the elemental content (P, S, K, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Hg, Pb) in brown rice, rice bran and the resulting white rice using microwave assisted decomposition followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. Additionally, individual rice grains at every polishing step were analyzed by laser ablation ICP-MS to generate elemental distribution maps. While P, K, Mn and Fe were predominantly located in bran layer, S, Cu, Zn, As, Se, Mo, Cd, and Hg were present in both the bran and endosperm. As the elemental distribution in the grain varies, polishing to produce white rice results in removal of different amounts of nutrient and toxic elements.

Geographical variation of arsenic distribution in paddy soil, rice and rice-based products: A meta-analytic approach and implications to human health

Arsenic is considered as ubiquitous toxic element belonging to the highest health hazard category. Wide ranges of natural as well as anthropogenic activities are subject to create global arsenic distribution in the broad sense. Rice is the major staple food consumed by world's population on the maximum scale. Growing environment of rice typically attributed by geographical origin may influence on arsenic bioavailability in rice grain. Over exploitation of arsenic contaminated, groundwater resources have recognised as major concern in agricultural perspective for rice production. On the other hand, biogeochemical weathering of arsenic bearing rocks as the geogenic origin, mining activities and application arsenical pesticides are recognised to be well known factors responsible to increase the soil arsenic level. Transfer of arsenic into rice is rightly acquainted from these possible sources of contamination in different regions around the world. Consequently, such substantial geographical variation reflects bioavailability as well as speciation of arsenic in rice. In this manuscript, we discuss the contribution of different arsenic entering pathways in soil-rice systems from regional variability. Furthermore, we attempted to apply the meta-analysis in order to predict the comparative risk assessment on distribution pattern of total and inorganic arsenic in rice commercialised from various rice producing regions of Asia, Europe and US by considering a selected number of data set an extensive range of market basket and field survey. In addition, we finally focus on health risk assessment associated by the consumption of rice and rice-based infant products as the dietary intake from the different of origin. Furthermore, we must detect and categorize the possible source of contamination, which may critically enhance the bioavailability of arsenic in rice in order to minimize the risk. These are the major aspects reviewed here.

A Comprehensive Review of Arsenic Exposure and Risk from Rice and a Risk Assessment among a Cohort of Adolescents in Kunming, China

Inorganic arsenic (iAs) is carcinogenic and highly concentrated in rice. Dietary exposure to iAs is concerning among adolescents due to their developmental stage and iAs’s long-latency effects. This paper aimed to assess iAs exposure from rice and related lifetime cancer risks (LCR) among adolescents in Kunming, China. A comprehensive literature review of iAs levels in rice and LCR in humans was also conducted. Average daily consumption of rice (ADC) was estimated from 267 adolescents (15–18 years). Rice samples obtained from 6 markets were analyzed for iAs concentration (AC). Estimated daily intake (EDI) of iAs was calculated using ADC, AC, and average body weight (BW). Lifetime Cancer Risk (LCR) was calculated using EDI and U.S. EPA derived iAs oral slope factor. The AC was 0.058 mg/kg and the average BW and ADC were 67.5 kg and 410 g/day for males and 55.5 kg and 337 g/day for females. The EDI and LCR were 3.52 × 10⁻⁴ mg/kg-BW/day and 5.28 × 10⁻⁴ for both males and females, with LCR 5 times above the U.S. LCR upper limit of 1.0 × 10⁻⁴. While the AC was below the Chinese maximum contaminant level of 0.2 mg/kg, study results indicated that Kunming adolescents may be at increased risk for iAs-related cancers.