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Article

Metal and Pesticide Assessments of Imported and Locally Cultivated Rice (Oryza sativa) in Senegal

by
Anna Ndiaye
1,
Alassane Traore
2,*,
Papa Sam Gueye
3,
Zachary Senwo
4,
Momar Ndiaye
1 and
Abdoulaye Diop
1
1
Département de Chimie, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar 10700, Senegal
2
Département de Physique, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar 10700, Senegal
3
Ceres Locustox, Km 15 Route de Rufisque, Dakar 10700, Senegal
4
Department of Natural Resources & Environmental Sciences, College of Agricultural, Life & Natural Sciences Alabama A&M University, Normal, AL 35762, USA
*
Author to whom correspondence should be addressed.
Appl. Sci. 2024, 14(7), 2876; https://doi.org/10.3390/app14072876
Submission received: 20 January 2024 / Revised: 25 February 2024 / Accepted: 26 February 2024 / Published: 29 March 2024
(This article belongs to the Section Agricultural Science and Technology)
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Abstract

:
Identifying heavy metal and pesticide contaminants is an essential step in assessing the health indicators of rice cultivation and consumption in Africa. Information on the contaminant levels of the imported and cultivated rice consumed in Senegal seems lacking. In this study, we assessed heavy metals, pesticides, ash, and protein in rice using rice samples from India, Thailand, South America, Vietnam, and China. Arsenic, Pb, Cd, Ni, Cu, Mo, Co, Cr, and Al are usually found in the soils used for rice cultivation in northern Senegal. While the heavy metal levels measured in soils were above the threshold limit, only Pb, Cd, and Al were found in cultivated rice. In all the analyzed rice samples from each country, there were certain amounts of Pb, As Al, and Cd. The concentration ranges in the six countries were as follows: 0.635–1.165 mg kg−1 for Pb, 0.047–0.438 mg kg−1 for As, 2.22–95.54 mg kg−1 for Al, and 0.002–0.082 mg kg−1 for Cd. The protein content in cultivated rice in Senegal was 7.31 mg kg−1, while the average from the imported rice ranged between 6.42% and 7.32%. The humidity levels in imported rice ranged between 11.12% and 12.95%. The fat content for the rice from six countries ranged between 0.22% and 0.67%, and the ash content ranged between 0.23% and 0.48%. These results allowed for the determination of the carbohydrate concentration, which varied between 79.18% and 80.82%. Indeed, freshly harvested rice grains typically contain around 80% carbohydrates. We noticed the presence of pesticides in all rice samples. The levels of three pesticides (total Pyrethrin, Bensulfuron-methyl, Propanyl, and 2,4D) were found to be beyond their maximum residue limits (MRLs) from the Codex Alimentarius, whereas deltamethrin was found to be below its MRL. This study indicates the presence of heavy metals carcinogenic to humans (Al, As, Cd, and Pb). Additionally, this study reveals the presence of deltamethrin, which is classified as probably carcinogenic to humans (Group 1), and 2,4-dichlorophenoxyacetic acid, which is classified as possibly carcinogenic to humans (Group 2B).

1. Introduction

Although rice is a main staple food source for over 50% of the world’s population, its major source of high metal toxicities is from soils [1]. Heavy metal contamination of food is a public health problem due to its potential accumulation in biological systems via transport from contaminated water and soils [2]. They may influence high blood pressure and anemia, or affect the lungs, kidneys, and bones [3]. Numerous studies have been conducted on the bioaccumulation of toxic metals in rice and their potential sources of exposure [4,5,6,7]. In November 2011, the IARC published a comprehensive review of more than 100 chemical, physical, occupational, and biological agents that have been classified by the IARC as carcinogenic to humans (Group 1), probably carcinogenic to humans (Group 2A), possibly carcinogenic to humans (Group 2B), and not classifiable as to their carcinogenicity to humans (Group 3).
Lead (Pb) is classified as probably carcinogenic to humans (group 2A) and Cadmium (Cd), aluminum (Al), and arsenic (As) are classified as carcinogenic to humans (group 1).
Deltamethrin is probably carcinogenic to humans (group 1) and 2,4-dichlorophenoxyacetic acid is possibly carcinogenic to humans (group 2B).
Senegal is one of the West African countries where rice constitutes its main cereal food source. The average consumption of milled rice per capita per year is approximately 75 kg, while it is around 52 kg in Asia [8]. In 2009, rice consumption amounted to 1.1 million tonnes; only 45% of what was consumed was produced locally, and 55% was imported from India, Thailand, and Vietnam. On average, the national rice production covers around 20 and not more than 30% of the country’s rice demand [9]. The Senegalese government has prioritized rice self-sufficiency and embarked on massive investments to enhance productivity within Africa [9]. The total production of local paddy rice was estimated at one million tonnes in 2018 compared with 559 tonnes in 2015, which demonstrates an increase of 102% in the past five years. Rice is the main food product consumed in Senegal and has been an important source of heavy metals through absorption effects [10]. Although numerous studies have shown the heavy metal contamination of rice in different countries [11], information is lacking regarding heavy metal contaminants in the rice consumed in Africa [12].
Being exposed to heavy metals is a human health concern. Effective agricultural soil management reduces soil contaminations and heavy metal accumulations in plants like rice [13,14]. While the total As in soils is toxic, its concentration in soils is not usually within the range to assess its potential human toxicity. The acute and chronic toxicities of As depend on the speciation or the various chemical forms and routes of exposure and absorption. Human activities (foundries, coal combustion, and various industrial activities) constitute most As inputs into the environment. As is mainly used to treat wood [15] and constitutes several plant protection products such as Pb or calcium arsenates.
The most assimilating toxic metal in rice is As, which is more efficient throughout seeds compared to other staple cereal crops [16]; inorganic As and dimethyl arsenic (DMA) dominate grain As speciation [17,18]. The key point sources of pollution in paddies and the resulting increase in As concentrations in grains have been characterized and documented in several studies and include the application of arsenical pesticides [19,20], irrigation with groundwater contaminated with As [21,22], and fertilization with municipal solid wastes [23]. The major problems arising in rice production in Asia are linked to rice breeding, the overuse of fertilizers and pesticides, the breakdown of irrigation infrastructure, oversimplified crop management, and a weak extension system [24]. This study provides the levels of heavy metals, especially Pb, Cd, As, Al, Mo, Ni, Cu, Cr, and B, and pesticides in 44 cultivated and imported rice sources and an assessment of the risks associated with the consumption of the rice.
According to the technical sheets for rice from the river valley prepared by The National Society for the Development and Exploitation of Land in the Delta of the Senegal River and the Valleys of the Senegal River and the Falémé (SAED), fertilizers such as urea or pesticide molecules such as propanil, Weedone (2,4D), Decis (deltamethrin), and Bensulfuron-methyl have to be monitored. This monitoring is performed to fulfill the requirement of the contents of pesticides found in food products.

2. Materials and Methods

2.1. Local and Imported Rice Sampling

The rice samples used for this study were obtained from the river valley in northern Senegal and various markets within the Dakar environs after a survey was conducted to find out the origin of rice sold in the various markets. The results of the survey showed that the rice came from India, China, Vietnam, Thailand, South America, and the Senegal River valley. We imported rice samples from India, Thailand, South America, Vietnam, and China. Sampling of the cultivated rice was carried out based on the rice brands consumed by the locals. All the local rice samples came from northern Senegal in the River Valley, cultivated using irrigation systems. The water gradient has a variable height of 5 to 10 cm depending on the vegetative stages. The origins and information on local rice were obtained from the labels on the packages and others are from the field.

2.2. Preparation and Measurement of Toxic Metals

The dried soil samples were sieved through a 2 mm sieve and about 0.2 g was weighed into digestion vessels. Add 3 mL of nitric acid (4.1) and 0.5 mL of hydrogen peroxide (4.5), and close the digestion bottle and the bottle holder correctly. Allow the pre-mineralization to take place outside the microwave oven (5.3) for approximately 30 min. Apply low microwave energy at the start of digestion then slowly increase the energy to high power maximum, to reach at least 210 °C. Maintain this temperature for at least 20 min, and cool for at least 20 min to 25 min. Dilute the mineralization solution accordingly with water. Treat a blank the same way. As, Al, Cd, B, and Pb contents in rice and soil were measured by ICP-MS [25]. Commercial standard solutions of 1000 mg/l were used to prepare the solutions for the calibration curve. The limit of detection for Cd is 0.0002 mg/kg, for Al 0.005 mg/kg, for Pb 0.001 mg/kg, and for As 0.0002 mg/kg. The recovery of heavy metals is measured in the range of 70–120%. We analyzed a blank.

2.3. Preparation and Measurement of Pesticides

Prior to the extraction procedure, the rice samples were milled and the dry soil samples were sieved through a 2 mm sieve. An amount of 5 g of milled rice or dried soil sample was weighed and placed into 50 mL centrifuge tubes for extraction. Then, 10 mL of organic solvent consisting of a 1:1 mixture of acetone–dichloromethane (DCM) was added to the samples. The centrifuge tubes with the samples were then placed in an ultrasonic bath and sonicated for one hour. Then, they were centrifuged at 2000 rpm for 15 to 20 min to separate the organic layer from the sample. The extracts were transferred to evaporation tubes by decanting or using a Pasteur pipette. The residue was re-extracted for 30 min with another 10 mL of the acetone–DCM mixture and the second extract was transferred to the same evaporation tube. The residue was re-extracted again for 30 min with another 10 mL of the acetone–DCM mixture and transferred to the same evaporation tube. Then, the whole volume was placed in a water bath at 55 degrees Celsius and evaporated to near dryness. Next, 1 mL of methanol was added and the volume was evaporated to dryness. Finally, the remaining residue was dissolved by cautiously shaking on the vortex with two aliquots of 0.5 mL of methanol that were each transferred to the same 1 mL volumetric tube and made up to volume with methanol. The samples were transferred to 2 mL GC vials and stored in a refrigerator until analysis by GC-MS (7890A–5975C) [26]. The detection limits for deltamethrin, 2,4D, Pyrethrin 1 and 2, Propanil, and Bensulfuron-methyl are 0.01 mg/kg. The recovery of pesticides measured in the range of 70–120%. We analyzed a blank. The analysis was carried out in the Laboratory for Environmental Analysis, Center for Applied Isotope Studies, University of Georgia.

Preparation and Measurement of Protein, Lipids, Ash, Lipid, Humidity and Total Carbohydrate

The main nutrients in rice grains are starch, protein, and lipids. The protein content was performed using a procedure that allows us to account for nitrogen in milling rice grain. A LECO TruSpec model CHN was performed to estimate protein content using the combustion method (Duma’s method). One method consisted of rice-free grain by combustion to measure nitrogen and using a thermal conductivity detector to assess the percent nitrogen content, which will be carried out to calculate the protein content, with 5.95 used as a rice protein conversion factor. The Kjeldahl method has been mostly applied to perform total nitrogen content [27]. Nitrogen content was then multiplied by a factor to arrive at the total protein content. Two assumptions have been taken into consideration based on this approach: dietary carbohydrates and fats do not contain nitrogen, and nearly all the nitrogen in the diet is present as amino acids in proteins. However, all the total nitrogen found in rice samples was multiplied by over 16% for a conversion factor of 6.25.
Ash: Typically, samples of 5 g are used in the analysis of ash content. Dry ashing procedures use a high-temperature muffle furnace capable of maintaining temperatures of between 550 °C for 3 h. Water and other volatile materials are vaporized and organic substances are burned in the presence of oxygen in the air to CO2, H2O, and N2. The food sample is weighed before and after ashing to determine the concentration of ash present (AOAC Official Method 942.05).
Lipids: Accurately weigh 5 g of the sample into the thimble/flask, and dry the sample in an oven at 102 °C for 5 h. After that, insert the thimble in a Sox let liquid/solid extractor. Accurately weigh a clean, dry 150 mL round bottom flash and put about 90 mL of petroleum ether in the flask. Assemble the extraction unit in an electric heating mantle or a water bath. Heat the solvent in the flask until it boils (adjust the heat source so that solvent drips from the condenser into the sample chamber at the rate of about 6 drops per second), and continue the extraction process for 6 h. Remove the extraction unit from the heat source and remove the extractor and condenser (replace the flask on the heat source and evaporate off the solvent).
Humidity: Dry the empty dish and lid in the oven at 105 °C for 3 h and transfer to the desiccator to cool. Weigh the empty dish and lid. Weigh about 3 g of sample to the dish. Spread the sample with a spatula. Place the dish with the sample in the oven. Dry for 3 h at 105 °C. After drying, transfer the dish with a partially covered lid to the desiccator to cool. Reweigh the dish and its dried sample (AOAC 930.15-1930).
Total Carbohydrate: content was determined by the formula below:
Total Carbohydrate (%) = 100 − [SUM (%Protein + %humidity + %lipid + %ash)].

3. Results

The results represented in Table 1 showed all local rice produced in the Senegal River regarding As, Cd, Pb, and Al contents. Aluminum concentrations ranged between 1.18 and 50.44 mg/kg and the average value is very significant at about 8.35 mg/kg compared to those obtained in the previous studies [26,28]. The recommended maximum Pb in rice is 0.3 mg/kg, according to WHO/FAO. An amount of 11.08% of rice samples analyzed contained over 0.1 mg/kg of Cd. The recommended value by the Food and Drug Administration for the Department of Health is around 15 mg/kg [29]; however, 82.4% of rice sampled contained over 0.1 mg/kg of Pb compared to the amount of Cd found in cultivated rice in Japan [11]. On average, the rice analyzed from each country showed certain amounts of Pb, As, Al, and Cd except rice from China (Table 2). The application of fertilizers is of concern on the agriculture base, Chinese farmers are applying 282 kg/ha of fertilizer at effective nutrition, a level already considered to be one of the highest in the world [13]. Generally, rice cultivations require a tiny selection of suitable areas for growth and an understanding of the environment surrounding the atmosphere. This atmosphere should be free of disease control, pest eradication, fertilization rate, and watering throughout the growing stages.
At present, farmers are increasingly using pesticides and inorganic fertilizers because they are not labor intensive, convenient, and enhance yields [30]. These suggest that heavy metals such as Cd, Pb, Hg, Cu, Cr, and Fe are introduced in soil and rice [31] in two major countries, Iran and China. These metals interfere with cell biological functions of living organisms [3,32,33]. When comparing results with research from [34], heavy metals in Thai rice seeds are found in 54 samples. The results of [35] revealed As content in polished white rice obtained from 10 countries including rice from Thai. The As detected in most rice is the inorganic form. The results also show that rice from the United States, Thailand, and Ghana contained As 0.22 mg/kg, 0.15 mg/kg, and 0.11 mg/kg, respectively [36].

3.1. Local and Imported Rice

Table 1 represents the concentrations of heavy metals content in local rice by targeting As, Cd, Pb, Al, Cu, Cr, Mo, and Ni.
The average metal contents (Al, As, Cd, Pb), the micronutrient B in local and imported rice, and the nutritional composition in percent are reported in Table 2.
K was the most abundant mineral component in all Local and imported rice with a range of 560.05 to 1012.07 mg/kg.

Acceptable Daily Intake (ADI) of Metals

Acceptable daily intake is an important consideration in assessing potential health risks associated with certain substances. In this study where the elemental concentration of toxic metals was determined, it helps to determine whether an individual’s level of exposure is within safe limits or exceeds acceptable levels, which can be used to inform risk management decisions and public health guidelines.
In Table 3, we summarized the calculation of the ADI based on the rice consumption in Senegal for an adult person of around 60 kg.
ADI (mg/kg/Day) = (Concentration of element × Consumption)/Weight body.

3.2. Soil

As, Pb, Cd, Ni, Cu, Mo, Co, Cr, and Al are found in the soil (Table 4) where rice is grown in northern Senegal. The measurements performed for the soil samples collected are high in toxic metals above the threshold limit. But, only Pb, Cd, and Al are found in cultivated rice. The concentration levels of the toxic elements in rice are lower than in soil.
The statistical analysis is added to Table 2 and it is related to the normal distribution of the data and the symmetric aspect of the obtained results.
A statistical study of the results has been made and graphically abstract as well.
In Figure 1, we highlighted the distribution of toxic metals such as Pb, As, and Cd in cultivated rice.
And, in Figure 2 below, we highlighted the distribution of toxic metals as Pb, As, and Cd in imported rice.

3.3. Pesticide Contents

We noticed the presence of pesticides in all rice samples, see Table 5. The levels of three pesticides (total Pyrethrin, Bensulfuron-methyl, Propanyl, and 2,4D) were found beyond the maximum residue limit (MRL) from the Codex Alimentarius. The limit values of total Pyrethrin, Bensulfuron-methyl, Propanyl, and 2,4D are 0.3 mg/kg, 0.01 mg/kg, 0.01 mg/kg, and 0.1 mg/kg, respectively [37,38]. Deltamethrin is found below the MRL for cereal and it was set to 2 mg/kg by the Codex Alimentarius.

4. Discussion

The presence of Pb, Cd, Al, As, and B is found in all imported and cultivated rice samples from Senegal, China, Thailand, Vietnam, and South America. Based on the representative of Pb in all samples, it is noted that 81% of Pb is present on cultivated rice and the results range between 0.21 and 2.22 mg/kg (Table 1). Of the six imported kinds of rice, the Pb concentrations are above the maximum tolerated limit by WHO/FAO, 2004, which is around 0.3 mg/kg. Similarly, the Food and Drug Administration of the Department of Health has conducted several analyses of different types of rice and the obtained values were above the limit of 0.1 mg/kg. On the other hand, the Cd concentrations for rice from the six countries are lower than the value set by the Food and Drug Administration of the Department of Health, which is around 0.1 ppm. Moussa Ndong et al. [11], revealed the presence of Pb and Cd in rice from northern Senegal below the concentrations specified by WHO/FAO standards and the Food and Drug Administration of the Department of Health [39]. The UN-authorized amount of As in rice is 0.2 ppm. As is a natural element of the earth’s crust, about 1.8 mg/kg on average [40], and is widely present in the environment, whether in the air, water, or soil. It is very toxic in its natural inorganic form and more present in rice than in the organic form [41]. However, inorganic arsenic is easily absorbed by rice, according to the WHO. We note the presence of As in all imported and cultivated rice; however, rice brands from Senegal, China, South America, and Vietnam exceeded the standard set by the WHO/FAO, which is around 0.2 mg/kg. In China, the maximum tolerated limit for As is 0.15 mg/kg.
As in drinking water and food can biologically accumulate at the bottom of the food chain. The main human exposure of such toxic metals, as As is from food consumption, and, upon prolonged intake of toxic elements, serious health effects may occur. With inorganic As, the most toxic fraction is known to cause skin, lung, and bladder cancer [42]. The presence of Pb and As in rice is different from one source to another [11]. Studies by Naseri et al. [10] showed certain amounts of Pb and Cd in local and imported rice grains sold in Shiraz, Lebanon [1]. The presence of Cd may be due to the nature of the soil, fertilizers used, and the quality of the irrigation water [3]. Several studies have suggested washing and soaking polished rice grains reduced Cd content by about 7%, indicating that Cd intake is overestimated when using Cd concentration data [43,44]. Cd in rice was estimated in the mean range of 21 mg/kg in Japan [45]. Al is present in all rice samples at concentrations ranging between 2.22 and 95.54 mg/kg. Knowledge of the relationship between the flood recession (duration, extension, and period) and soil (moisture, texture, and depth) can be a good asset in adaptation strategies (sowing period, crop varieties). All these physical and chemical parameters can be correlated with fertilizer concentrations and periods of use.
The Bore concentration as a micronutrient is reported in Table 2, which is about 0.01 and 1.17 mg/kg. Its important role, in plant metabolism, is highlighted by its presence in cell wall synthesis and maintaining plant structure and integrity [46,47]. Freshly, harvested rice grains contain about 80% carbohydrate, which includes starch, glucose, sucrose, and dextrin. In Table 2, the amount of carbohydrates is less than that expected regarding the local rice contents of carbohydrates in China, India, and Vietnam. However, South American and Thailand-imported rice present a very acceptable amount of carbohydrate content. Senegal has a protein content in cultivated rice of around 7.31%; meanwhile, the average from imported rice is around 6.42% and 7.32%. In the literature, it is found that the amount of protein present in seeds varies from 10 to 40% of the dry weight [48]. We have found that the results of imported and cultivated sativa rice indicate that the amount of protein is very low. Due to its nutritional quality and higher digestibility, rice is still among the most consumed cereals [49]. The humidity levels of all rice varied between 11.12% and 12.95% (Table 2), which is lower than the safe moisture content (14%) for the safe storage of processed rice [50]. Both local and imported rice fulfilled the 12% required humidity for long-term storage to avoid insect infestation and microbial growth [51]. The fat content was significantly different for all rice except for that from Senegal and India, which is almost the same value. Rice from Thailand had the highest fat content, followed by rice from Senegal and India at about 0.6% and South America at 0.3%, whereas Vietnamese rice exhibited the lowest fat content (0.2%) (Table 2). It is important to note that the presence of high levels of Al in rice can vary depending on factors such as geographic location, soil composition, irrigation practices, and industrial activities in the surrounding area. Monitoring and regulation of Al levels in rice production are essential to ensure food safety and protect public health. Additionally, proper cooking and processing methods may help reduce Al content in rice to some extent.
When rice plants absorb more B than necessary, it can lead to a condition known as B toxicity (see Table 3). Symptoms of B toxicity in rice plants may include leaf chlorosis, leaf tip burning, stunted growth, and reduced crop yield. From a human health perspective, consuming rice with high levels of B may pose health risks. Excessive intake of B has been associated with adverse effects on human health, including gastrointestinal issues, skin irritation, and potential developmental problems. Therefore, it is essential to monitor and regulate B levels in rice to ensure food safety and prevent potential health hazards. Factors contributing to high levels of B in rice include soil composition, irrigation water quality, and agricultural practices. Soil with naturally high B content or irrigation water containing elevated B levels can contribute to increased B uptake by rice plants.
This study recommends periodic monitoring for endrin and trifluralin. The prime method is a Persistent Organic Pollutant heavily regulated by the Stockholm Convention. The latter, trifluralin, is a herbicide that is very stable in water with a high potential to bioaccumulate in biological tissues of organisms and biomagnify throughout the food web.

5. Conclusions

Our findings clearly clarify the quality of imported and cultivated rice in Senegal. We imported rice brands from India, Thailand, South America, Vietnam, and China. The cultivated rice sampling was carried out based on rice brands consumed by Senegalese people. As, Pb, Cd, Ni, Cu, Mo, Co, Cr, and Al were found in the soil media where rice is grown. The concentration levels of the toxic elements in cultivated rice are lower than observed in the soils. This is probably due to the variety of selections or to the natural translocations of macronutrients and toxic elements within rice compartments from the plant roots. Monitoring and regulation of Al levels in rice production are essential to ensure food safety and protect public health. Additionally, proper cooking and processing methods may help reduce Al content in rice, to some extent. To mitigate the risk of B accumulation in rice, agricultural practices such as proper irrigation management, soil amendment, and selection of B-tolerant rice varieties can be implemented. Additionally, regular monitoring of B levels in rice and adherence to safety regulations are crucial for maintaining food safety standards. The effects of the degree of milling must be taken into consideration for the accounting of protein contents during industrial processing. At this stage of the study, we need to validate the impact of industrial processing by carrying out the changes due to the degree of milling correlating with protein contents in rice plants. It was pointed out there is no longer a relationship between toxic trace metals and pesticide presence in cultivated rice samples regarding the source of contamination coming from anthropogenic activities. Senegal is a member of several organizations, gathering several countries, working for the regulation of the use of pesticides, and metal contaminants in environmental monitoring in West Africa. Pesticide information on this broad range of herbicides in water and rice plants is most of the time not available to the farmers and/or to the consumers.
The toxic kinetics and the eco dynamics have to be taken into consideration during the period of spraying pesticides over the crops in the river valley. The water monitoring period has to be shortened due to the fact that it constitutes the beverage of five million consumers through the Water Company (SDE) of Senegal.

Author Contributions

Conceptualization, A.T., Z.S., A.D. and A.N.; methodology, A.N., A.D. and Z.S.; validation, A.D., A.N. and Z.S.; formal analysis, Z.S. and A.N.; writing—original draft preparation, A.T. and A.N.; writing—review and editing, Z.S. and M.N.; supervision, A.D.; administrative issues, M.N., P.S.G. and A.D. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the 2018 USDA-FAS Borlang International Agricultural Science and Technology Fellowship program, Alabama A&M University, the University of Georgia Athens, and the Ceres Locustox Foundation.

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Acknowledgments

We are very grateful to Rakesh K. Singh and Casimir C. Akoh from the Department of Food Science and Technology in the College of Agriculture and Environmental Sciences for their kind help. The support received from the CEA-AGRISAN and the head of Ceres Locustox was an utmost contribution to the sampling material and travel support to reach rice fields. We would like to express our gratitude to Abdoulaye Diop posthumously, who was the main mentor of this study during its conceptualization.

Conflicts of Interest

The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

References

  1. Naseri, M.; Vazirzadeh, A.; Kazemi, R.; Zaheri, F. Concentration of some heavy metals in rice types available in Shiraz market and human health risk assessment. Food Chem. 2015, 175, 243–248. [Google Scholar] [CrossRef] [PubMed]
  2. Lokeshwari, H.; Chandrappa, G.T. Impact of heavy metal contamination of Bellandur Lake on soil and cultivated vegetation. Curr. Sci. 2006, 91, 622–627. [Google Scholar]
  3. Khaniki, G.R.; Zozali, M.A. Cadmium and lead contents in rice (Oryza sativa) in the north of Iran. Int. J. Agric. Biol. 2005, 7, 1026–1029. [Google Scholar]
  4. Batista, B.L.; Nacano, L.R.; de Freitas, R.; de Oliveira-Souza, V.C.; Barbosa, F. Determination of Essential (Ca, Fe, I, K, Mo) and Toxic Elements (Hg, Pb) in Brazilian Rice Grains and Estimation of Reference Daily Intake. Food Nutr. Sci. 2012, 03, 129–134. [Google Scholar] [CrossRef]
  5. Lin, H.-T.; Wong, S.-S.; Li, G.-C. Heavy metal content of rice and shellfish in Taiwan. J. Food Drug Anal. 2004, 12, 5. [Google Scholar] [CrossRef]
  6. Shimbo, S.; Zhang, Z.-W.; Watanabe, T.; Nakatsuka, H.; Matsuda-Inoguchi, N.; Higashikawa, K.; Ikeda, M. Cadmium and lead contents in rice and other cereal products in Japan in 1998–2000. Sci. Total. Environ. 2001, 281, 165–175. [Google Scholar] [CrossRef]
  7. Zhang, Z.W.; Watanabe, T.; Shimbo, S.; Higashikawa, K.; Ikeda, M. Lead and cadmium contents in cereals and pulses in north-eastern China. Sci. Total. Environ. 1998, 220, 137–145. [Google Scholar] [CrossRef]
  8. Samal, P.; Babu, S.C.; Mondal, B.; Mishra, S.N. The global rice agriculture towards 2050: An inter-continental perspective. Outlook Agric. 2022, 51, 164–172. [Google Scholar] [CrossRef]
  9. FAO. Rice Market Monitor Trade and Markets Division; Food and Agriculture Organization of the United Nations: Rome, Italy, 2010. [Google Scholar]
  10. Zakir, H.M.; Islam, F.; Quadir, Q.F.; Rahman, A. Metallic Health Risk through Consumption of Different Rice Varieties Cultivated in Industrial Wastewater Irrigated Farmers’ Fields of Bhaluka Area, Bangladesh. Curr. J. Appl. Sci. Technol. 2020, 39, 76–91. [Google Scholar] [CrossRef]
  11. Tsukahara, T.; Ezaki, T.; Moriguchi, J.; Furuki, K.; Shimbo, S.; Matsuda-Inoguchi, N.; Ikeda, M. Rice as the most influential source of cadmium intake among general Japanese population. Sci. Total. Environ. 2003, 305, 41–51. [Google Scholar] [CrossRef]
  12. Ndong, M.; Mise, N.; Okunaga, M.; Kayama, F. Cadmium, arsenic and lead accumulation in rice grains produced in Senegal river valley. Fundam. Toxicol. Sci. 2018, 5, 87–91. [Google Scholar] [CrossRef]
  13. Sun, L.; Zheng, M.; Liu, H.; Peng, S.; Huang, J.; Cui, K.; Nie, L. Water management practices affect arsenic and cadmium accumulation in rice grains. Sci. World J. 2014, 2014, 596438. [Google Scholar]
  14. Li, H.; Luo, N.; Li, Y.W.; Cai, Q.Y.; Li, H.Y.; Mo, C.H.; Wong, M.H. Cadmium in rice: Transport mechanisms. Influencing factors and minimizing measures. Environ. Pollut. 2017, 224, 622–630. [Google Scholar] [CrossRef] [PubMed]
  15. Laperche, V.; Hammade, V. Diagnostic rapide sur site. Utilisation de méthodes d′évaluation de la teneur en métaux de sols pollués par mesure de leur susceptibilité magnétique et par fluorescence X. In Rap. CNRSSP/02/05; 2002; 16 p + ann. Available online: https://infoterre.brgm.fr/rapports (accessed on 25 February 2024).
  16. Sohn, E. Contamination: The toxic side of rice. Nature 2014, 514, S62–S63. [Google Scholar] [CrossRef]
  17. Williams, P.N.; Price, A.H.; Raab, A.; Hossain, S.A.; Feldmann, J.; Meharg, A.A. Variation in Arsenic Speciation and Concentration in Paddy Rice Related to Dietary Exposure. Environ. Sci. Technol. 2005, 39, 5531–5540. [Google Scholar] [CrossRef] [PubMed]
  18. Torres-Escribano, S.; Leal, M.; Vélez, D.; Montoro, R. Total and Inorganic Arsenic Concentrations in Rice Sold in Spain, Effect of Cooking, and Risk Assessments. Environ. Sci. Technol. 2008, 42, 3867–3872. [Google Scholar] [CrossRef] [PubMed]
  19. Garelick, H.; Jones, H.; Dybowska, A.; Valsami-Jones, E. Arsenic Pollution Sources. In Reviews of Environmental Contamination Volume 197. Reviews of Environmental Contamination and Toxicology; Springer: New York, NY, USA, 2009; Volume 197. [Google Scholar]
  20. Matthew, A.D.; Antonio, J.S.P.; Maria, A.; Francis, S.; Claire, P.; Tracy, P.; Anala, G.; Habibul, A.; Margaret, R.K. Assessment of human dietary exposure to arsenic through rice. Sci. Total Environ. 2017, 586, 1237–1244. [Google Scholar] [CrossRef]
  21. Meharg, A.A.; Rahman, M. Arsenic Contamination of Bangladesh Paddy Field Soils: Implications for Rice Contribution to Arsenic Consumption. Environ. Sci. Technol. 2002, 37, 229–234. [Google Scholar] [CrossRef]
  22. Britta, P.F.; Carolin, F.K.; Andrea, E.C.; Blanco, S.C. Dimethylated Thioarsenates: A Potentially Dangerous Blind Spot in Current Worldwide Regulatory Limits for Arsenic in Rice. J. Agric. Food Chem. 2022, 70, 9610–9618. [Google Scholar] [CrossRef]
  23. Bhattacharyya, P.; Chakrabarti, K.; Chakraborty, A. Residual effect of municipal solid waste compost on microbial biomass and activities in mustard growing soil: Restwirkung von müllkompost auf die mikrobielle biomasse und mikrobielle aktivitaten in boden mit senfbewuchs. Arch. Agron. Soil Sci. 2003, 49, 585–592. [Google Scholar] [CrossRef]
  24. Peng, S.; Tang, Q.; Zou, Y. Current Status and Challenges of Rice Production in China. Plant Prod. Sci. 2009, 12, 3–8. [Google Scholar] [CrossRef]
  25. NF EN 17053; Aliments des Animaux—Méthodes D’échantillonnage et D’analyse—Dosage par ICP-MS (Multi Méthode) des Éléments Traces, Métaux Lourds et Autres Éléments Inorganiques Présents dans les Aliments. European Committee for Standardisation: Paris, France, 2018.
  26. Ofoe, R.; Thomas, R.H.; Asiedu, S.K.; Wang-Pruski, G.; Fofana, B.; Abbey, L. Aluminum in plant: Benefits, toxicity and tolerance mechanisms. Front. Plant Sci. 2023, 13, 1085998. [Google Scholar] [CrossRef]
  27. AOAC. Official Methods of Analysis, 17th ed.; The Association of Official Analytical Chemists: Gaithersburg, MD, USA, 2000. [Google Scholar]
  28. Roy, B.; Bhadra, S. Effects of Toxic Levels of Aluminium on Seedling Parameters of Rice under Hydroponic Culture. Rice Sci. 2014, 21, 217–223. [Google Scholar] [CrossRef]
  29. FDA. Dietary Supplements Foods and Beverage; FDA: Silver Spring, MD, USA, 2023.
  30. Kheankhun, N.; Sringam, J.; Kumpunit, W.; Wattanakornsiri, A.; Phengphai, P. Contaminated heavy metal in rice of Surin province, Thailand. Naresuan Univ. J. Sci. Technol. 2020, 28, 55–64. [Google Scholar]
  31. Roya, A.Q.; Ali, M.S. Heavy metals in rice samples on the Torbat-Heidarieh market, Iran. Food Addit. Contam. Part B 2017, 10, 59–63. [Google Scholar] [CrossRef]
  32. Bundschuh, J.; Nath, B.; Bhattacharya, P.; Liu, C.-W.; Armienta, M.A.; López, M.V.M.; Lopez, D.L.; Jean, J.-S.; Cornejo, L.; Macedo, L.F.L.; et al. Arsenic in the human food chain: The Latin American perspective. Sci. Total. Environ. 2012, 429, 92–106. [Google Scholar] [CrossRef] [PubMed]
  33. Ahmed, M.K.; Shaheen, N.; Islam, M.S.; Habibullah-al-Mamun, M.; Islam, S.; Mohiduzzaman, M.; Bhattacharjee, L. Dietary intake of trace elements from highly consumed cultured fish (Labeo rohita. Pangasius pangasius and Oreochromis mossambicus) and human health risk implications in Bangladesh. Chemosphere 2015, 128, 284–292. [Google Scholar] [CrossRef]
  34. Siri-anusornsak, W.; Soiklom, S.; Thanaruksa, R. Determination of Heavy Metals (Cd, Cr and Pb) in Thai Rice; Kasetsart University: Bangkok, Thailand, 2017; pp. 65–71. [Google Scholar]
  35. Meharg, A.A.; Lombi, E.; Williams, P.N.; Scheckel, K.G.; Feldmann, J.; Raab, A.; Zhu, Y.; Islam, R. Speciation and Localization of Arsenic in White and Brown Rice Grains. Environ. Sci. Technol. 2008, 42, 1051–1057. [Google Scholar] [CrossRef] [PubMed]
  36. Nookabkaew, S.; Rangkadilok, N.; Mahidol, C.; Promsuk, G.; Satayavivad, J. Determination of arsenic species in rice from Thailand and other Asian countries using simple extraction and HPLC-ICP-MS analysis. J. Agric. Food Chem. 2013, 61, 6991–6998. [Google Scholar] [CrossRef] [PubMed]
  37. Maybury, R.B. Codex Alimentarius Approach to Pesticide Residue Standards. J. AOAC Int. 1989, 72, 538–541. [Google Scholar] [CrossRef]
  38. Anderson, L. National Food Safety Standards Maximum Residue Limits for Pesticides in Food; Gain Report Number CH17016; USDA: Beijing, China, 2017; p. 218.
  39. U.S. Food and Drugs. Arsenic in Food and Dietary Supplement. Contents 06-01-2023. Available online: https://www.fda.gov/food/environmental-contaminants-food/arsenic-food-and-dietary-supplements (accessed on 1 September 2022).
  40. Kabata-Pendias, A. Trace Elements in Soils and Plants, 4th ed.; CRC Press: Boca Raton, FL, USA, 2022; p. 105. [Google Scholar]
  41. Mania, M.; Rebeniak, M.; Szynal, T.; Starska, K.; Wojciechowska-Mazurek, M.; Postupolski, J. Exposure assessment of the population in Poland to the toxic effects of arsenic compounds present in rice and rice based products. Rocz. Państwowego Zakładu Hig. 2017, 68, 339–346. [Google Scholar]
  42. Ramírez-Zavala, B.; Reuß, O.; Park, Y.-N.; Ohlsen, K.; Morschhäuser, J. Environmental Induction of White–Opaque Switching in Candida albicans. PLoS Pathog. 2008, 4, e1000089. [Google Scholar] [CrossRef] [PubMed]
  43. Shindoh, K.; Yasui, A. Changes in Cadmium Concentration in Rice during Cooking. Food Sci. Technol. Res. 2003, 9, 193–196. [Google Scholar] [CrossRef]
  44. Jorhem, L.; Åstrand, C.; Sundström, B.; Baxter, M.; Stokes, P.; Lewis, J.; Grawé, K.P. Elements in rice from the Swedish market: 1. Cadmium, lead and arsenic (total and inorganic). Food Addit. Contam. Part A 2008, 25, 284–292. [Google Scholar] [CrossRef] [PubMed]
  45. Kitagishi, K.; Yamane, I. (Eds.) Heavy Metal Pollution in Soils of Japan; Japan Science Society Press: Tokyo, Japan, 1981; p. 302. [Google Scholar]
  46. Goldbach, H.E.; Wimmer, M.A.; Findeklee, P. Discussion paper: Boron—How can the critical level be defined? J. Plant Nutr. Soil Sci. 2000, 163, 115–121. [Google Scholar] [CrossRef]
  47. Oso, A.A.; Ashafa, A.O. Nutritional Composition of Grain and Seed Proteins. Grain Seed Proteins Funct. 2021, 31–50. [Google Scholar] [CrossRef]
  48. Shewry, P.R.; Napier, J.A.; Tatham, A.S. Seed Storage Proteins: Structures and Biosynthesis. Plant Cell Am. Soc. Plant Physiol. 1995, 7, 945–956. [Google Scholar]
  49. Anjum, F.M.; Pasha, I.; Bugti, M.A.; Batt, M.S. Mineral composition of different rice varieties and their milling fractions Pak. J. Agric. Sci. 2007, 44, 51–58. [Google Scholar]
  50. Rules on Sorting. In Packaging and Presentation of Rice Ministry of Agriculture; National Secretariat of Supply: Athens, Greece, 1988.
  51. Adair, C.R.; Bollich, C.N.; Bowman, D.H.; Joson, N.E.; Johnston, T.H.; Webb, B.D.; Atkins, J.G. Rice breeding and testing method in the United States. In Rice in the United States: Varieties and Production; Department of Agriculture of the United States: Washington, DC, USA, 1973; pp. 22–27. [Google Scholar]
Applsci 14 02876 g001
Figure 1. (a) Distribution level of Cadmium content in cultivated rice, (b) distribution level of arsenic content in cultivated rice, (c) distribution level of Plomb content in cultivated rice.
Figure 1. (a) Distribution level of Cadmium content in cultivated rice, (b) distribution level of arsenic content in cultivated rice, (c) distribution level of Plomb content in cultivated rice.
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Figure 2. (a) Distribution level of Cadmium content in imported rice, (b) distribution level of Plomb content in imported rice, (c) distribution level of arsenic content in imported rice.
Figure 2. (a) Distribution level of Cadmium content in imported rice, (b) distribution level of Plomb content in imported rice, (c) distribution level of arsenic content in imported rice.
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Table 1. Metal contents in local rice based on dry mass (mg/kg).
Table 1. Metal contents in local rice based on dry mass (mg/kg).
Rice BrandMetal Contents
AsCdPbAlB
CASL<LoD *0.131.5550.442.90
Salam<LoD *0.070.754.922.46
Terral Entier0.240.072.019.441.94
Coumba<LoD *0.07<LoD ***7.011.31
Royal Senegal<LoD *<LoD **2.225.281.74
Thiebou Walo<LoD *0.141.112.430.35
Karolina<LoD *0.071.313.04<LoD ****
GIE Mbodj and Freres0.240.070.892.13<LoD ****
Thiossane0.050.070.631.18<LoD ****
Rixel0.430.070.147.14<LoD ****
Terral Brise<LoD *0.07<LoD ***2.58<LoD ****
Royal Senegal Maison<LoD *0.07<LoD ***4.74<LoD ****
Riz In Field #1<LoD *<LoD **0.2817.842.20
Riz In Field #2<LoD *<LoD **0.216.86<LoD ****
Riz In Field #3<LoD *<LoD **0.764.962.48
Riz In Field #4<LoD *<LoD **1.683.573.36
Average0.240.080.858.351.17
NB: Cr, Cu, Mo, Ni are not detected in Local rice samples. LoD * = 0.005; LoD ** = 0.002; LoD *** = 0.021; LoD **** = 0.001.
Table 2. Average metal contents in local and imported rice on dry mass (mg/kg) with proximate composition value.
Table 2. Average metal contents in local and imported rice on dry mass (mg/kg) with proximate composition value.
ParametersSenegalIndiaChinaSouth AmericaVietnamThailandSkewnessKurtosis
Al8.35195.5415.4116.4412.2222.6733.34733411.977796
Pb0.8461.1650.6850.8581.0060.6350.494440−0.934050
Cd0.0800.0820.0020.0690.0350.0690.217715−0.792027
As0.2410.4380.1420.2400.2400.0472.1777044.112999
B1.1720.6590.0980.2691.6690.0980.389291−1.554029
K831.0591012.069957.799910.409560.039655.898−1.8140714.909083
Protein (%)7.317.326.427.517.096.821.0056222.311697
Fat (%)0.600.590.450.30.220.67−0.130692−1.379063
Humidity (%)12.7612.2612.7311.1212.9511.36−0.5906981.910566
Ash (%)0.440.430.390.480.230.42−0.290591−0.532768
Total
Carbohydrate (%)		79.1279.3579.9780.2379.5080.820.0381000.035373
The recovery of heavy metals measured in the range of 70–120%.
Table 3. Determination of the acceptable daily intake based on toxic metals in rice (mg/kg/day).
Table 3. Determination of the acceptable daily intake based on toxic metals in rice (mg/kg/day).
AlPbCdAsB
Senegal0.0330.00340.00030.0010.0047
India0.3820.00470.00030.00170.0026
China0.02160.00270.000010.00060.00004
South America0.02580.00340.00030.0010.0011
Vietnam0.00890.00400.00010.0010.0067
Thailand0.01070.00250.00030.00020.0004
ADI (WHO,2011)-0.025-0.0003-
ADI (USDA)----0.1
RFD (US-EPA)-0.00050.001-
Table 4. Metal contents in cultivated soils (mg/kg).
Table 4. Metal contents in cultivated soils (mg/kg).
Samples AsCdCoCrCuMoNiPbAl
Soil3.460.6910.6734.5115.6617.8814.009.506449
No crop6.520.696.9343.4417.9130.8112.6312.2811,975
Dry soil4.460.423.2118.754.0422.176.347.607460
Salty soil3.900.566.8934.9316.7722.6111.139.398669
Table 5. List of targeted pesticides in countries in mg/kg.
Table 5. List of targeted pesticides in countries in mg/kg.
Targeted PesticidesSenegalIndiaChinaSouth AmericaVietnamThailand
Pyrethrin I43.8525.8558.3833.9638.3137.09
Pyrethrin II1.481.091.051.431.711.19
Propanil0.730.420.370.250.320.67
2,4D83.5643.86120.1913.697.4872.7
Deltamethrin<0.01<0.01<0.01<0.01<0.01<0.01
Bensulfuron methyl0.650.541.050.610.670.85
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Ndiaye, A.; Traore, A.; Gueye, P.S.; Senwo, Z.; Ndiaye, M.; Diop, A. Metal and Pesticide Assessments of Imported and Locally Cultivated Rice (Oryza sativa) in Senegal. Appl. Sci. 2024, 14, 2876. https://doi.org/10.3390/app14072876

AMA Style

Ndiaye A, Traore A, Gueye PS, Senwo Z, Ndiaye M, Diop A. Metal and Pesticide Assessments of Imported and Locally Cultivated Rice (Oryza sativa) in Senegal. Applied Sciences. 2024; 14(7):2876. https://doi.org/10.3390/app14072876

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Ndiaye, Anna, Alassane Traore, Papa Sam Gueye, Zachary Senwo, Momar Ndiaye, and Abdoulaye Diop. 2024. "Metal and Pesticide Assessments of Imported and Locally Cultivated Rice (Oryza sativa) in Senegal" Applied Sciences 14, no. 7: 2876. https://doi.org/10.3390/app14072876

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