Heavy metals and probabilistic risk assessment via rice consumption in Thailand

Uncertainty and sensitivity analyses of human health risk from bioaccessible arsenic exposure via rice ingestion in Bangkok, Thailand

BACKGROUND

Rice can be a source of arsenic (As) exposure, causing health impacts after ingestion.

OBJECTIVE

This study analyzed health risks due to As exposure through rice consumption, focusing on both bioaccessible (bAs) and total (tAs) As levels.

METHODS

Monte Carlo simulations were applied to determine health risk uncertainties and to analyze factors influencing health risks.

RESULTS

Cooked white and brown rice contained lower tAs and bAs than FAO/WHO standards of 0.20 and 0.35 mg/kg, respectively. As became less bioaccessible after cooking (14.0% in white rice and 18.5% in brown rice). Non-carcinogenic effects (MOS < 1) were found in 5% of children. Carcinogenic effects (MOE<100), especially lung cancer, were found in 75% of adults, with a probable incidence of 7 in 1,000,000. The lowest and highest annual cancer cases were 18 in 10,000,000 adolescents and 15 in 1,000,000 adults, respectively. The risks were mainly affected by body weight and bAs concentration.

SIGNIFICANCE

The results identified a certain risk level of non-carcinogenic effects in children and adolescents as well as carcinogenic effects in adults. The per capita consumption of rice in Thai adults should be reduced to prevent incidences of lung cancer.

Metal(loid)s Spatial Distribution, Accumulation, and Potential Health Risk Assessment in Soil-Wheat Systems near a Pb/Zn Smelter in Henan Province, Central China

To understand the influence of Pb/Zn smelter on surrounding environment, 110 soil and 62 wheat grain samples (62 paired samples) were collected nearby a Pb/Zn smelter in Jiaozuo City, Henan Province, China. The content and spatial distribution of metal(loid)s in the soil-wheat system, and the potential health risk via consumption of wheat grains were determined. Results showed that the average content of Pb, Cd, As, Cu, Zn, and Ni in soil were 129.16, 4.28, 17.95, 20.43, 79.36, and 9.42 mg/kg, respectively. The content of Cd in almost all soil samples (99.1%) exceeded the national limitation of China (0.6 mg/kg). Spatial distribution analysis indicated that atmospheric deposition might be the main pollution source of Pb, Cd, As, and Zn in soil. In addition, the average content of Pb, Cd, As, Cu, Zn, and Ni in wheat grain were 0.62, 0.35, 0.10, 3.7, 35.77, and 0.15 mg/kg, respectively, with the average Pb and Cd content exceeding the national limitation of China. The average bioaccumulation factor of these metal(loid)s followed the following order: Zn (0.507) > Cu (0.239) > Cd (0.134) > Ni (0.024) > Pb (0.007) > As (0.006). Health risk assessment indicated that the average noncarcinogenic risk of children (6.78) was much higher than that of adults (2.83), and the carcinogenic risk of almost all wheat grain is higher than the acceptable range, with an average value of 2.43 × 10−2. These results indicated that humans who regularly consume these wheat grains might have a serious risk of noncarcinogenic and carcinogenic diseases.

Pollution monitoring, risk assessment and target remediation of heavy metals in rice from a five-year investigation in Western Fujian region, China

Recently, rice contamination by heavy metals (HMs) has become a severe problem. Taking the Western Fujian region as an example in this study, a total of 1311 rice samples containing eight HMs were collected from 2015 to 2019, then used to explore their pollution characteristics, health risks, and Spatio-temporal variations, finally derive the target remediation areas of the key pollutants. The results showed that average concentrations of all the HMs had not reached the limits of the National Standards of Food Safety, but pollution indexes of As (0.783) and Cu (0.665) were at accumulation level (>0.6), which posed high pollution risks. Furthermore, locations of higher HMs concentrations coincided with those of higher pollution estimation probabilities. The non-carcinogenic risk (4.150, 2.434) and carcinogenic risk (4.96 × 10^-3, 2.92 × 10^-3) for children and adults cannot be negligible, As and Cd were the largest contributors. Children were more susceptible than adults due to the metal concentrations and rice intake rate. The spatio-temporal changes indicated that a decreasing trend in average concentrations of HMs (except Cr), but As (0.37%-0.88%) contents increased in the west and northeast parts, and so did Cd (1.92%-5.11%) in the central region during monitoring. For the target remediation, particular regions in the western and eastern were used as risky areas of As and Cd, respectively. Our results will provide theoretical support for the pollution management of HMs in rice.

Migration of heavy metals in the soil-grape system and potential health risk assessment

The accumulation of heavy metals in soil may introduce them to the food chain and cause health risks for humans. In the present study, 43 pairs of soil and grape samples (leaf and fruit) were collected form vineyards in the suburbs of Kaifeng city (wastewater-irrigated area in Henan Province, China) to assess the heavy metal (Pb, Cd, Cu, Zn and Ni) pollution level in soil, heavy metal accumulation in different grape tissues and the potential health risk via consumption of grapes. The results showed that the average contents of Pb, Cd, Cu, Zn and Ni in vineyard soil were 42.27, 3.08, 62.33, 262.54 and 26.60 mg/kg, respectively. Some of these soil samples were severely contaminated with Cd and Zn, with an average pollution index (P_i) of 5.14 and 0.88, respectively. Most of these soil samples were severely polluted by heavy metals, with an average Nemerow integrated pollution index (P_N) of 3.77. The bioavailable heavy metals were negatively correlated with soil pH and positively correlated with soil organic matter (OM). In addition, heavy metals were more likely to accumulate in grape leaves, and their contents in grape pulp were all within the maximum permissible limit set by China (GB 2762-2017). The average bioaccumulation factors (BFs) of Pb, Cd, Cu, Zn and Ni in grape pulp were 0.007, 0.096, 0.160, 0.078 and 0.023, respectively. Health risk assessment indicated that there was no noncarcinogenic risk for grape consumers (adults and children). However, the carcinogenic risk (CR) ranged from 4.95 × 10^-7 to 2.17 × 10^-4, and the CR value of three grape samples was higher than 10^-4, indicating that a probability of carcinogenic disease existed for humans who regularly consumed the grapes from this region.

Heavy Metals and Probabilistic Risk Assessment via Pheretima (a Traditional Chinese Medicine) Consumption in China

Earthworms are known to accumulate inorganic contaminants from the soil; they are also used as a traditional Chinese medicine (TCM) called Pheretima, which might cause safety problems with long-term exposure. Here, this study was conducted to determine and analyze the level of heavy metal contamination such as arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), and lead (Pb) in Pheretima and then explore the probabilistic health risks caused by 8 heavy metals in 98 batches of Pheretima using Monte Carlo simulation. A risk assessment strategy was conducted to assess heavy metal-associated health risk of Pheretima based on consumption data. For random consumption sampling, the results found that the non-carcinogenic risk of As is higher than the acceptable level, and the carcinogenic risk levels of As and Cr exceeded the acceptable risk recommended by the USEPA. Cr and As were regarded as the priority metals for risk control in the present study. Finally, it was recommended that the dosing frequency should be less than 24 d/y. In general, this study conducted a probabilistic risk assessment of heavy metals in Pheretima, which would be of significance for policy makers to take effective strategies to improve the quality and safety of Pheretima.

Tracing the Geographical Origin of Thai Hom Mali Rice in Three Contiguous Provinces of Thailand Using Stable Isotopic and Elemental Markers Combined with Multivariate Analysis

Rice is a staple food for more than half of the world’s population. The discrimination of geographical origin of rice has emerged as an important issue to prevent mislabeling and adulteration problems and ensure food quality. Here, the discrimination of Thai Hom Mali rice (THMR), registered as a European Protected Geographical Indication (PGI), was demonstrated. Elemental compositions (Mn, Rb, Co, and Mo) and stable isotope (δ¹⁸O) in the rice were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) and elemental analyzer isotope ratio mass spectrometry (EA-IRMS), respectively. The recoveries and precisions of all elements were greater than 98% and lower than 9%, respectively. The analytical precision (±standard deviation) was below ±0.2‰ for δ¹⁸O measurement. Mean of Mn, Rb, Co, Mo, and δ¹⁸O levels was 14.0 mg kg⁻¹, 5.39 mg kg⁻¹, 0.049 mg kg⁻¹, 0.47 mg kg⁻¹, and 25.22‰, respectively. Only five valuable markers combined with radar plots and multivariate analysis, linear discriminant analysis (LDA) could distinguish THMR cultivated from three contiguous provinces with correct classification and cross-validation of 96.4% and 92.9%, respectively. These results offer valuable insight for the sustainable management and regulation of improper labeling regarding geographical origin of rice in Thailand and other countries.

Ecological and human health risk evaluation of potential toxic metals in paddy soil, rice plants, and rice grains (Oryza sativa) of Omor Rice Field, Nigeria

Potential toxic metals from natural and anthropogenic sources accumulate in soil and plants, and represent important environmental contamination challenges. The ecological and human health risks of the potential toxic metals in rice grain, paddy soil, and rice plants of Omor rice field were assessed. The total metal concentration from the four sampling sections (mg/kg) were soil-Zn (29.51 ± 2.23), Mn (55.27 ± 8.10), Cd (5.49 ± 2.24), Cu (2.94 ± 1.47), Pb (14.35 ± 6.54), and Cr (27.06 ± 8.31); rice grain-Zn (21.70 ± 5.44), Mn (3.30 ± 0.21), Cd (00.14 ± 0.11), Cu (2.80 ± 0.34), Pb (11.98 ± 0.58), and Cr (15.86 ± 2.79); and for rice plant-Zn (5.24 ± 1.93), Mn (4.68 ± 1.91), Cd (0.21 ± 0.11), Cu (4.88 ± 0.61), Pb (15.24 ± 6.16), and Cr (46.5 ± 6.05). The estimated daily intakes for adult showed that Cd and Pb exceeded the safe limit by 1% and 93%, respectively. The metal hazard quotients (Zn-0.0007, Mn-0.00019, Cd-0.16, Cu-0.19, and Cr-0.0000077) were less than 1 indicating no probable health risk originating from their exposure. The total hazard index (0.35) also suggests no probable health risk connected with the rice consumption. The metals' ecological risk indices of the soil showed low-risk (< 40), except Cd in some sections of the rice field which indicated moderate potential ecological risk (40-80).

Development, Validation and Application of an ICP-SFMS Method for the Determination of Metals in Protein Powder Samples, Sourced in Ireland, with Risk Assessment for Irish Consumers

A method has been developed, optimised and validated to analyse protein powder supplements on an inductively coupled plasma-sector field mass spectrometer (ICP-SFMS), with reference to ICH Guideline Q2 Validation of Analytical Procedures: Text and Methodology. This method was used in the assessment of twenty-one (n = 21) elements (Al, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Pb, Pt, Sn, Ti, Tl, V) to evaluate the safety of thirty-six (n = 36) protein powder samples that were commercially available in the Irish marketplace in 2016/2017. Using the determined concentrations of elements in samples (µg·kg-1), a human health risk assessment was carried out to evaluate the potential carcinogenic and other risks to consumers of these products. While the concentrations of potentially toxic elements were found to be at acceptable levels, the results suggest that excessive and prolonged use of some of these products may place consumers at a slightly elevated risk for developing cancer or other negative health impacts throughout their lifetimes. Thus, the excessive use of these products is to be cautioned, and consumers are encouraged to follow manufacturer serving recommendations.

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.

Ultratrace Detection of Nickel(II) Ions in Water Samples Using Dimethylglyoxime-Doped GQDs as the Induced Metal Complex Nanoparticles by a Resonance Light Scattering Sensor

This study aimed to synthesize dimethylglyoxime (DMG) (N-source)-doped graphene quantum dots (N-GQDs) via simultaneous pyrolysis of citric acid and 1.0% (w/v) DMG. The maximum excitation wavelength (λmax, ex = 380 nm) of the N-GQD solution (49% quantum yield (QY)) was a red shift with respect to that of bare GQDs (λmax, ex = 365 nm) (46% QY); at the same maximum emission wavelength (λmax, em = 460 nm), their resonance light scattering (RLS) intensity peak was observed at λmax, ex/em = 530/533 nm. FTIR, X-ray photoelectron spectroscopy, XRD, energy-dispersive X-ray spectroscopy, and transmission electron microscopy analyses were performed to examine the synthesized materials. The selective and sensitive detection of Ni2+ using the RLS intensity was performed at 533 nm under the optimum conditions consisting of both 25 mg L-1 N-GQDs and 2.5 mg L-1 DMG in the ammonium buffer solution of pH 9.0. The linearity of Ni2+ was 50.0-200.0 μg L-1 with a regression line, y = 5.031x - 190.4 (r 2 = 0.9948). The limit of detection (LOD) and the limit of quantitation (LOQ) were determined to be 20.0 and 60.0 μg L-1, respectively. The method precision expressed as % RSDs was 4.90 for intraday (n = 3 × 3) and 7.65 for interday (n = 5 × 3). This developed method afforded good recoveries of Ni2+ in a range of 85-108% when spiked with real water samples. Overall, this innovative method illustrated the identification and detection of Ni2+ as a DMG complex with N-GQDs, and the detection was highly sensitive and selective.

A Fluorescence Switching Sensor for Sensitive and Selective Detections of Cyanide and Ferricyanide Using Mercuric Cation-Graphene Quantum Dots

This study aims to use graphene quantum dots (GQDs) as a fluorescence switching sensor (turn on-off) for the simultaneous detection of cyanide (CN-) and ferricyanide [Fe(CN)6]3- in wastewater samples. The GQDs were synthesized by pyrolyzing solid citric acid. The intrinsic blue color of the solution was observed under ultraviolet irradiation. The fluorescence spectrum was maximized at both excitation and emission wavelengths of 370 and 460 nm, respectively. The fluorescence intensity of GQDs decorated with Hg2+ (turn-off mode as the starting baseline) could be selectively turned on in the presence of CN- and once back to turn-off mode by [Fe(CN)6]3-. The fluorescence switching properties were used to develop a fluorescence turn-on-off sensor that could be used to detect trace amounts of CN- and [Fe(CN)6]3- in water samples. For highly sensitive detection under optimum conditions (Britton-Robinson buffer solution in the pH range of 8.0-9.0, linearity ranges of 5.0-15.0 μM (R 2 = 0.9976) and 10.0-50.0 μM (R 2 = 0.9994), respectively, and detection limits of 3.10 and 9.48 μM, respectively), good recoveries in the ranges of 85.89-112.66% and 84.88-113.92% for CN- and [Fe(CN)6]3-, respectively, were recorded. The developed methods were successfully used for the simultaneous and selective detection of CN- and [Fe(CN)6]3- in wastewater samples obtained from local municipal water reservoirs.

Association between heavy metals and colon cancer: an ecological study based on geographical information systems in North-Eastern Iran

Background

Colorectal cancer has increased in Middle Eastern countries and exposure to environmental pollutants such as heavy metals has been implicated. However, data linking them to this disease are generally lacking. This study aimed to explore the spatial pattern of age-standardized incidence rate (ASR) of colon cancer and its potential association with the exposure level of the amount of heavy metals existing in rice produced in north-eastern Iran.

Methods

Cancer data were drawn from the Iranian population-based cancer registry of Golestan Province, north-eastern Iran. Samples of 69 rice milling factories were analysed for the concentration levels of cadmium, nickel, cobalt, copper, selenium, lead and zinc. The inverse distance weighting (IDW) algorithm was used to interpolate the concentration of this kind of heavy metals on the surface of the study area. Exploratory regression analysis was conducted to build ordinary least squares (OLS) models including every possible combination of the candidate explanatory variables and chose the most useful ones to show the association between heavy metals and the ASR of colon cancer.

Results

The highest concentrations of heavy metals were found in the central part of the province and particularly counties with higher amount of cobalt were shown to be associated with higher ASR of men with colon cancer. In contrast, selenium concentrations were higher in areas with lower ASR of colon cancer in men. A significant regression equation for men with colon cancer was found (F(4,137) = 38.304, P < .000) with an adjusted R² of 0.77. The predicted ASR of men colon cancer was − 58.36 with the coefficients for cobalt = 120.33; cadmium = 80.60; selenium = − 6.07; nickel = − 3.09; and zinc = − 0.41. The association of copper and lead with colon cancer in men was not significant. We did not find a significant outcome for colon cancer in women.

Conclusion

Increased amounts of heavy metals in consumed rice may impact colon cancer incidence, both positively and negatively. While there were indications of an association between high cobalt concentrations and an increased risk for colon cancer, we found that high selenium concentrations might instead decrease the risk. Further investigations are needed to clarify if there are ecological or other reasons for these discrepancies. Regular monitoring of the amount of heavy metals in consumed rice is recommended.

Bioaccessibility-corrected health risk of heavy metal exposure via shellfish consumption in coastal region of China

A systematic investigation into bioaccessible heavy metals in shellfish Crassostrea ariakensis, Chlamys farreri, and Sinonovacula constricta from coastal cities Shenzhen, Zhoushan, Qingdao, and Dandong was carried out to assess the potential health risk to residents in coastal regions in China. The bioaccessible fractions of heavy metals were (μg‧g-1): Zn (0.63-15.01), Cu (0.10-12.91), Cd (0.01-0.64), As (0.11-0.33), Cr (0.07-0.12), Pb (0.01-0.03). The bioaccessibilities of heavy metals were Cr 61.86%, inorganic As (iAs) 60.44%, Pb 55.74%, Cu 46.83%, Zn 28.16%, and Cd 24.99%. As for child and adult, the bioaccessibility-corrected estimated daily intakes were acceptable and the non-carcinogenic risks posed by heavy metals were not obvious. The carcinogenic risks posed by bioaccessible heavy metals at the fifth percentile were 10-fold higher than the acceptable level (10-4), with iAs and Cd to be the major contributors, regardless of child or adult. The probabilistic estimation showed the low risk of shellfish consumption, which was verified by higher values of maximum allowable consumption rate and monthly meals at the 95 percentile; while some control of consumption rate and monthly meals was necessary for reducing heavy metal exposure of most shellfish samples, except for the safe consumption of S. constricta for both child and adult in Qingdao and Shenzhen, China.

Content of Toxic Elements in 12 Groups of Rice Products Available on Polish Market: Human Health Risk Assessment

Background: Rice is one of the most commonly consumed grains. It could be a good source of nutrients in a diet, but its consumption could also contribute to exposure to toxic elements. All rice products available on the Polish market are imported, which may pose a particular concern as to the safety of their consumption. The aim of our study was to estimate the content of As, Cd, Pb, and Hg in rice products and to assess the health risk indicators related to exposure to toxic elements consumed with rice products among the adult population in Poland. 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) available in the Polish market were obtained. The content of Hg was determined using the atomic absorption spectrometry method (AAS). To measure As, Cd, and Pb, inductively coupled plasma-mass spectrometry (ICP-MS) was used. The health risk was assessed by calculating several indicators. Results: The average As, Cd, Pb, and Hg contents in all studied products were 123.5 ± 77.1 μg/kg, 25.7 ± 26.5 μg/kg, 37.5 ± 29.3 μg/kg, and 2.8 ± 2.6 μg/kg, respectively. Exceedance of the limit established by the Polish National Food Safety Standard was observed in one sample as regards the As content and exceedance of the European Commission standard in two samples for Hg. The samples of foods imported from European markets (n = 27) had statistically higher As content (p < 0.05) than those imported from Asian countries (n = 53). The values of health risk indicators did not show an increased risk for the Polish adult population. However, the daily intake of 55 g of rice corresponds to the benchmark dose lower confidence limit (BMDL) for Pb. Conclusion: The studied rice products could be regarded as safe for consumption by the Polish population as far as the content of As, Cd, Pb, and Hg is concerned.