This systematic review examined the role of arsenic contamination in affecting the food chain. The study emphasised factors that are influencing the uptake of rice. The primary aim of the study was to assess the challenges in the food chain due to the presence of arsenic; analyse the role of arsenic in the contamination of soil; evaluate the impact of arsenic in the food chain, and identify the factors related to arsenic that influence the uptake in rice and to provide recommendations for reducing arsenic in the food chain that influence the uptake in rice. The qualitative research methodology was used to investigate the aims and objectives of the study, where data was collected through secondary sources. Secondary data was examined through the tool of content analysis by considering all measures essential for secondary data analysis. This systematic review explored the increased level of arsenic in rice's huge impact on the food chain industry. It was identified that the increasing use of arsenic in rice is contaminating the soil and, thus, the groundwater, ultimately affecting the whole ecosystem. The factors related to arsenic that influence the uptake in rice include pH, phosphate, microorganisms, organic substances, and flooding. This review proposed recommendations to provide training on discriminating high-arsenic and low-arsenic sources, blending low-arsenic water with high-arsenic water in order to get an acceptable concentration level of arsenic and installing of arsenic removal system at necessary places.
Arsenic (As) is a natural element in soil, water, and food. Arsenic is usually present in agricultural land because it is an essential element that facilitates vegetation growth (Shakoor et al., 2016). However, it is crucial to comprehend that arsenic levels in the soil must be maintained in limited amounts to ensure that cultivated crops are not contaminated with excessive arsenic- a condition known as arsenic poisoning (Li et al., 2016). Furthermore, arsenic levels must be checked constantly, especially when fertilizer has been applied to soils, to ensure the risk of arsenic contamination is minimised (Jain and Chandramani, 2018). Lindsay and Maathuis (2017) explain that arsenic has two forms: organic and inorganic. The author further describes that organic arsenic is naturally occurring and is present in the soil, water, and air. During farming, the organic arsenic is absorbed in the crops as per their concentration in the soil. However, Rahman et al. (2018) reported that the inorganic arsenic compound is considered detrimental to health. According to Shrivastava et al. (2017), the absorption of arsenic and contamination of food like vegetables, fruits and grains are among the key causes of arsenic poisoning in major parts of the world arsenic is not present naturally in drinking water. Abdul et al. (2015) explain that the high toxicity of arsenic leads to individuals suffering from chronic and prolonged pain in their stomach, kidneys, liver and coronary heart diseases and diabetes. The International Agency for Research on Cancer (IARC) has categorised arsenic as a carcinogen because it causes lung, bladder, liver, kidney and skin cancer in individuals who consume excessive arsenic rice (Ruíz-Huerta et al., 2017). According to an experiment conducted by Shi et al. (2016) to measure the levels of arsenic in rice, the researchers found that in the soil where the rice was being cultivated, arsenic was present in the soil, equating to 5.60mg/kg. This was because the water being used to irrigate the soil already contained toxic substances such as ammonia, and nitrates/nitrites, which increased the levels of arsenic within the soil, thereby being absorbed by crops in greater amounts (Hojsak et al., 2015). In the study of Davis et al. (2017), the researcher tested out 223 samples of rice to find out the concentration of arsenic in those rice. After testing all the samples, the researchers revealed that the highest concentration of arsenic was found in brown rice, followed by basmati brown, whole grain brown rice, and aromatic brown rice. The researchers further tested brown rice by removing its hull and described that with the bran removed to produce white rice during the milling process, the white rice contained 20 times more arsenic levels than normal, indicating arsenic contamination (Davis et al., 2017).
There are many research articles and published data available reporting the uptake of arsenic in rice (Ma et al., 2016; Seyfferth et al., 2016; Suriyagoda, Dittert, and Lambers, 2018) and discuss those factors that contribute to the addition of arsenic in soil, water or air. Various studies discuss factors that impact arsenic uptake in rice and explain how each factor affects the uptake. These studies also discuss the potential adverse health effects of ingesting rice containing high arsenic levels, leading to cancer development. Wang et al. (2016) describe that during arsenic stress, the production of reactive oxygen species is increased, leading to membrane damage in rice plants along with non-specific oxidation of proteins and lipid membranes and causing damage to the DNA. Furthermore, the study of Althobiti, Sadiq and Beauchemin (2018) highlights that since rice is an efficient accumulator of silica as compared to other crop plants, the concentration of arsenic in the plant increases due to increased accumulation of silicic acid in the crop, which leads to a higher concentration of arsenic exceeding the safe limit, which is 0.39 ppm should be present in the soil. In the study of Otero et al. (2016), the author describes that uncertainties, such as varying levels of absorption by different rice plants, the rate at which inorganic arsenic is absorbed in the body, and the accurate molecular mechanism in the body, which leads to cancer formation, can be noticed in experiments concerning the investigation of inorganic arsenic in rice as pointed out by the FDA and the US Food and Drug Administration. The uncertainties are seen in the consumption level of rice and rice products which have been contaminated with inorganic arsenic. The main factors determining the increase of arsenic in soil and consequently in rice pertain to the location of where it was planted, along with the methods employed to process the rice and the overall plant physiology (Mishra, Mattusch and Wennrich, 2017). Numerous studies have carried out different factors and different varieties of rice in different geographical locations to analyse the soil conditions that affect the uptake of rice. Hence, conducting a systematic review of arsenic in the food chain and the factors that influence the uptake in rice in this study allows the researcher to be knowledgeable of all the factors and review appropriate recommendations facilitating a reduction in arsenic contamination in rice.
This research aims to conduct a systematic review of arsenic in the food chain and identify the factors that influence the uptake of arsenic in rice. The objectives of this research are as follows:
The research questions of this research are as follows:
The structure of this research pertains to the execution of this research throughout five chapters whereby. Chapter one introduces the research and background for a better understanding of this study. In this chapter, the aim and objectives of the study are developed and noted to ensure that subsequent chapters of the study conform to the objectives developed and are being fulfilled during the execution. The research problem has also been identified and described as why it was necessary to conduct research on the selected topic of the study.
Chapter two of this research consists of a literature review, whereby different studies will be reviewed for data collection, developing arguments, and providing facts and figures regarding arsenic contamination in the food chain and the aspects that impact its uptake in rice. This chapter provides an explanation of the different factors influencing the uptake of arsenic in rice and provides a theoretical framework as well.
Chapter three of this study provides an explanation and justification for the methodology adopted for successfully executing this research. It includes information regarding the research philosophy adopted, the research approach, the methods of data collection and data analysis and justifications to depict why it was necessary to adopt a philosophy or research approach.
Chapter four includes the analysis of the data and their results and discussion. In this chapter, data that has been collected with the method mentioned in chapter three is analysed as per the analysis method also mentioned. After the data analysis and the results are obtained, these results are discussed based on the study's objectives.
Chapter five is the final chapter of this research and conforms to provide the researcher's conclusion and final thoughts on this research. The data analysis findings were summarised, and appropriate recommendations were given to reduce the uptake of arsenic in rice.
Arsenic is one of the toxic metalloids for animals and plants. Arsenic is released into the soil through the use of contaminated irrigation water, some anthropogenic activities and mining (Li et al., 2014). Moreover, in many countries, rice is one main food whose annual production is extremely high. As analysed from the report of The United States Department of Agriculture in 2014, the production of rice was observed as 474.86 million tons by the world's major producers such as India, China, Bangladesh and Vietnam (Bastías and Beldarrain, 2016). As reported, some of these countries use groundwater with arsenic contamination and thus resulting in soil contamination with high levels of arsenic (Awasthi et al., 2017).
Additionally, it has been observed that rice is an efficient arsenic accumulator because of the soil's biochemical characteristics (Bastías and Beldarrain, 2016). It has been estimated that more than 150 million people worldwide have been affected due to the increased concentrations of arsenic. One of the routes to arsenic exposure in humans is oral ingestion. Li et al. (2014) reported in their research that arsenic contamination is greatly visible in countries with huge populations, such as Bangladesh, China, India, Turkey, Columbia, Chile and Argentina. Furthermore, Li et al. (2014) state that the worst affected country is Bangladesh, and it is due to the wide presence of Arsenic in groundwater used for drinking, therefore exposing its population.
However, the soil also has the ability to transport or absorb arsenic. The International Agency for Cancer Research Arsenic has reported that arsenite (AsIII) and arsenate (AsV) are determined as carcinogenic agents (Bastías and Beldarrain, 2016). Therefore, the increasing rice production is also increasing the harm caused by arsenic and has become an important concern for the scientific community (Bastías and Beldarrain, 2016). According to Azam, Sarker and Naz (2016), the foods that are produced on soils are impacted by the mining activities of the Pb-Zn and due to the uptake of arsenic; these mining activities are determined crucial for health. A survey was taken, and the results showed that the concentration of arsenic in all the rice does not satisfy the national food standards. In contrast, the least arsenic is observed in the rice cultivators “SY-89” and “DY-162” (Li et al., 2014). Additionally, it has been analysed that the arsenic accumulation within rice plants is strongly related to soil properties such as phosphorous, silicon, pH, organic matter and clay ((Awasthi et al., 2017; Bastías and Beldarrain, 2016).
This chapter of the research has assessed the critical literature review of the previous studies to analyse their results related to the arsenic in the food chain and the factors associated with arsenic that influence the uptake of rice. Further, it also presents the impact of arsenic on the food chain, followed by a literature gap and an important point to be concluded in the chapter summary.
Nightingale’s environmental theory was developed by Florence Nightingale and described the methods allowing to increase the well-being of individuals and enhance their health. The use of Nightingale’s environmental theory aids in this research because a systematic review is being conducted to evaluate the factors that influence the uptake of arsenic in rice. Since arsenic is considered toxic, it promotes the development of cancer cells in the body. This environmental theory proposed by Nightingale describes utilising natural resources to improve the individual's health. (de Florence Nightingale and Crítica, 2015). By utilising natural resources to promote the well-being of a person, it would allow for an enhanced recovery process. However, Pirani (2016) highlights that many factors affect the natural resources of the environment, polluting them and consequently reducing the effectiveness of these resources in facilitating the health of the individual. The theory further describes the environmental factors that promote an individual’s health; these factors include: the intake of fresh environmental air; Clean and fresh environmental air would allow people to inhale an increased amount of clean oxygen, which is free from any carcinogenic elements, thereby increasing the efficiency of their lungs and purity of their blood (Mughal and Irshad Ali, 2017). By drinking pure and clean water, an individual's internal organs will always remain healthy since the body does not need to extract all the poisonous material being ingested (Kamau, 2015). Cleanliness of the environment; the overall cleanliness of the environment allows for the reduction of diseases developed in that environment which would affect the person's health. Since arsenic is a compound that can be found in soil, water and air, this theory allows for a better understanding of the adverse health effects of arsenic contamination in the food chain. It allows for the development of appropriate recommendations where different methods and procedures can be employed to provide people with clean water, clean air and safe amounts of arsenic ingestion into the body.
The Theory of Pollution Policy describes that it is impossible to eliminate pollution that is emanating from a process. Smith (2018) highlights that no process in the world produces no waste products, thereby not harming the environment. With the aid of this theory, an extensive understanding of the processes can be done to determine the processes that retain arsenic compounds in the food chain. Since arsenic is a toxic compound and higher levels of arsenic are poisonous, it is important to note that the process employed during the extraction of rice retains much of the arsenic within the rice, which results in it being unsafe for consumption. According to this theory, it is important for people to identify the sources of pollution and research methods to reduce the levels of pollution contaminating their daily consumable products and damaging their environment (Rowe et al., 2016).
Furthermore, all consumable goods need to have well-defined property rights, which allow for the safe trading of these goods and are safe for consumption. Without having such rights, it is possible that goods being traded may not be at par with safety standards of consumption and can affect the well-being of the individual who consumes such products (Åström, (2017). Hu and McKitrick (2016) explain that with the use of the theory of pollution policy, the sources or processes which produce the highest waste or contaminate food sources and the environment can be identified along with other factors of influence as well and can allow individuals to work on processes that reduces as much pollution as possible. However, De Vries and Hanley (2016) have pointed out that in some cases, this theory can be difficult to put into practice because it is difficult to measure and different the damage is done to the environment by certain sources. Furthermore, it is also difficult to monitor and enforce pollution policies in a certain area and difficult to add taxes on pollution considering the political and financial costs. Pope III et al. (2015) shed light that market-based instruments provide some level of flexibility to polluters in the sense that regarding agriculture, a certain amount of toxic substance within the product has been indicated, and the products should not cross the specified limit. Ebenstein et al. (2017) depict that adopting a command and control approach allows an enhanced level of control regarding the pollution of consumable products by inducing a specific limit. Consumable goods being transported to different areas provide a classic example that allows the government to control the level of pollution or toxic substances in the products and enables full control. Failing to comply with the safe levels of toxic substances in the products allows the stakeholders to destroy the product or resend them so that their toxicity levels are reduced for safe consumption (Mohai and Saha, 2015).
In the food chain, arsenic is considered to be of high severity. Bakhat et al. (2017) have stated that the easiest form of ingesting arsenic is through food. The author further states that the Joint FAO/WHO Expert Committee on Food Additives (JECFA) studied arsenic consumption through food. The result of the meeting was that the committee had eradicated the Provisional maximum Tolerable Weekly Intake (PTWI) perimeter for ingesting arsenic of 15mg/kg body weight (bw) (Bakhat et al., 2019).
Zia et al. (2017) assert that arsenic enters the food chain through irrigation water, which is usually contaminated. The author further states that groundwater is the main drinking water source in numerous countries, which usually mixed with arsenic.
|Country||Area sq. mile||Population||Proportion of groundwater|
Groundwater used by countries (Zia et al., 2017)
From Table 1, it can be seen that around one-third of the world’s population makes use of groundwater for drinking purposes. The World Health Organisation (WHO) guideline strictly states that the maximum consumable threshold of arsenic in drinking water is 10 µg/L. However, Kumarathilaka et al. (2018) believe that numerous developing countries use 50 µg/L of arsenic in their drinking water as a standard which could be an indicator of arsenic contamination. This is relevant to the food chain because it shows arsenic can be consumed through drinking water too. The quantity might be different, but the consumption does occur.
The dietary arsenic intake is also an aspect that must be considered in the food chain. Majumdar, Kumar and Bose (2020) assert that dietary arsenic is the main basis of arsenic exposure in most developing countries. People who are high fish consumers would consume a high quantity of organic arsenic from this specific food group. Data related to the absorption of total arsenic shows that arsenic in foods is mainly a combination of inorganic species and oranosenicals comprising arsenobetaine (Punshon et al., 2017). The factual total arsenic absorptions in different foodstuffs vary from the nation, depending on the food type and the rising conditions that surround it (which are the type of soil, water, geochemical activity, using arsenical pesticides), and the processing methods.
|Country||Sampling method/ Other info||Arsenic intake (µg/kg bw per day)|
|Bangladesh||Average food intake without water||3.01||0.88|
|Five scenarios (including water)||2.68-5.07||-|
|Small community without water||-||1.68-3.00|
|India||Urine Analysis in arsenic contaminated areas (DD)||-||3.32-12.9|
|China||Total Dissolved Solids (including water)||-||0.24-0.76|
|China (Taiwan)||Small community without water (adult)||-||0.91|
|Japan||Total Dissolved Solids including water (Adult)||-||0.36-0.46|
|Europe||Adult (European Food Safety Authority)||-||0.21-0.61|
|Canada||Total Dissolved Solids (All without water)||-||0.29|
|USA||TDA (adult, water included in some studies||-||0.08-0.20|
|Australia||>17years (MB) not per Kg bw||41||-|
Dietary Intake (Azam, Sarker and Naz, 2016)
From table 2 above, it can be seen that there are variations in the dietary intake of adults, which imitates mainly the inconsistency in the consumption forms of arsenic-rich food groups (fish, shellfish, and meats), with their intake rates not high either (Azam, Sarker and Naz, 2016). Moreover, it also shows confirmation regarding regional differences in arsenic intake that occurs when human health is assessed for any effects of arsenic contamination.
Mukherjee et al. (2017) view the abrupt and long-term influence of using arsenic-contaminated water for irrigating paddy soils as the root through which arsenic transmits from water to the soil and eventually into the food chain. This alarming situation needs to be controlled by the people and government at all levels. Bastías and Beldarrain (2016) state that soil arsenic level is usually increased by 1 µg/g per annum due to the constant use of irrigation with water that has arsenic contamination. This notion was further supported by Kwon, Nejad and Jung (2017), who mentioned in their study that irrigation water which is rich in arsenic, can increase the levels of arsenic in agricultural soil up to five times. Although the element arsenic is not a crucial element for plants and animals, it plays a vital role in food crops in its growth factor. Suriyagoda, Dittert and Lambers (2018) state in their study that food crops, which are vegetables and cereals, become the path through which arsenic makes its way into the food chain. However, a key aspect to note here is that for fishes, the phytoplanktons are the cause through which fishes are able to consume arsenic and make their way to the food chain. The author further states that the food crops reflect the levels of arsenic in the environment, in which they have been cultivated through soil and irrigation water. This is the point where the build-up of arsenic in rice field soil and its role in the food chain through uptake by the rice plant is seen as a key issue.
Arsenic is a universal chemical element in the biosphere that transpires naturally in both inorganic and organic forms. The role of arsenic in soil contamination is vital because it creates an environment through which plants can survive in the food chain. Arsenic in acidic conditions creates compounds with aluminium and iron, and under alkaline conditions, calcium arsenate is seen to be the predominant compound. The role of the bioavailability of arsenic in the uptake of arsenic from soil to plants is another vital aspect to consider. Awasthi et al. (2017) believe that the significant inorganic arsenic composites are sodium arsenite, arsenic trioxide, arsenic acid and arsenates trichloride, and arsenic pentoxide (which are lead and calcium arsenates). The author further states that organic arsenic compounds are methylmalonic acid, dimethylarsinic acid, arsanilic acid, and arsenobetaine (AB). AB is seen as the leading organoarsenic in marine biota. Afzal, Hussain and Farooqi (2018) mention other organoarsenicals comprising arsenocholine, dimethloxyarsylethanol, trimethylammonium lactate, arsenic which comprises sugars, and phospholipids which are found in fish. The author further states that arsenites and arsenates are available in water, even though methylarsonic and dimethylarsinic acids are at low stages.
Zecchin et al. (2017) assert that rice plants are exposed to arsenic by numerous factors. The author further states that rice plants accumulate arsenic which naturally exists in the soil or is added through groundwater irrigation or through contaminated soil additives, as seen in the figure below
Bakhat et al.
Groundwater Irrigation - (Bakhat et al., 2019)
Bakhat et al. (2019) reported that there are combined pieces of evidence which prove that high rice-producing nations like India, Bangladesh, Taiwan, and China, tend to exceed the usual absorption of arsenic in soil (10.0 mg/kg) and the extreme standard allowed by the United States Environmental Protection Agency which is 20.0mg/kg as shown in the figure below.
Agricultural soil (mg arsenic/kg)
Groundwater (µg arsenic/L)
Arsenic Concentration (Awasthi et al., 2017)
Bangladesh is shown in three rows because of different levels of arsenic in groundwater. In China and Taiwan, the organic arsenic composite roxarsone exists in poultry brood, which is usually utilised as a fertiliser for rice, usually present at sea-level rice plants. Chatterjee, Sharma and Gupta (2017) believe that rice grain yield is decreased by arsenic absorption of the soil where the limit of the roxarsone/kg soil which killed rice plant was 200mg. It can be seen clearly that the arsenic absorption in the rice grain surpassed the statutory acceptable limit of 0.01 that has been set by the WHO (Wang et al., 2020).
Costa et al. (2016) assert that rice plants uptake arsenic largely in the form of arsenic III, arsenic V, dimethlarsinic acid (DMA) and monomethylarsonic acid (MMA) via the roots. Of these elements, arsenic III is considered to be the major type. The author further states that after accumulation, there are different forms of arsenic species that do not change throughout translocation to diverse plant parts, mainly shoot, root and grain. Arsenic III and DMA are the main species which were noticed in the United States rice (Boye, Lezama-Pacheco and Fendorf, 2017).
He et al. (2020) believe that agriculture condiments, such as fertilizers, desiccants and pesticides, are the key causes of arsenic in the soil. The author further states that low stages of arsenic in nitrogen and potassium fertilisers, along with lime, also plays a significant role in the uptake of rice. The possible arsenic accumulation level, which is increased in soils, is mainly due to the repeated application of arsenic that comprises fertilisers. Ma et al. (2017) assert that sources of drinking and irrigation water pollution from Concentrated Animal Feeding Operations (CAFOs) comprise absolute expulsions, open feedlots, action and stowage lagoons, land usage of compost to the fields and manure stocks. The CAFOs from the animals’ wastes can cause arsenic pollution in different parts of the world due to the extensive use of feed additives with organoarsenic.
The bioavailability of arsenic present in the soil is another factor that influences the arsenic during the uptake of rice. Bakhat et al. (2017) state that the origin and type of bioavailability of arsenic can vary significantly. The author further states that water-soluble arsenic level is more efficiently connected with the arsenic substance in the plant than in the soil. The parameters of soil possibly affect arsenic accumulation in rice, which are the arsenic content, soil texture, plant-available silicon, plant-available phosphorous and absorption of poorly crystalline iron-(hydr)oxides.
Du et al. (2019) focus on the soil properties and components that influence the solubility of arsenic and its toxicity. The organic carbon content, pH, ionic robustness of the soil solution, cation conversation capacity and iron oxides are the vital aspects which affect the arsenic availability in soils. Pokhrel et al. (2020) mention that soil environments can differ from site to site. This means that the phytoavailability of nutrients and contaminants can differ via the rhizosphere. It should be noted here that the influence of limits which are iron, manganese, phosphorous, organic matter contents, pH value, the occurrence of microorganisms and flood, tends to clarify the arsenic concentrations in the soil of the rice plants (Di et al., 2019).
The impact of various factors of bioavailability/soil concentrations plays a major role in the uptake of rice. The main impacts that would be analysed are from the effect of manganese and iron, the influence of pH, the effect of phosphate, microorganisms, organic substances, and flooding.
Effect of manganese and iron
Bakhat et al. (2017) state in their study that manganese and iron precipitate as iron and manganese oxides in a toxic atmosphere. The author further states that there is a rising similarity between iron and manganese oxides and arsenic, along with residue redox possible. The firmness of iron and iron (hydr)oxides mainly depends on the pH of the deposit (Awasthi et al., 2017). Afzal, Hussain and Farooqi (2018) believe that iron transpires in soluble procedures in an acidic atmosphere. In a non-aligned power of hydrogen (pH), the iron can persist in a solution with low redox or is considered a soluble organic compound in toxic soils. Zia et al. (2017) believe that iron and manganese (hydr)oxides decrease the arsenic flexibility in deep soil horizons. This leads to iron acting as a vigorous purpose in the arsenic circulation on the rice field. Arsenic mobility occurs through adsorption on iron oxides which substitutes the surface hydroxyl groups with arsenic ions and through the creation of unsolvable secondary oxidation minerals and shapeless iron III arsenates (Kumarathilaka et al., 2018).
Majumdar, Kumar and Bose (2020) are of the view that spatial circulation of arsenic absorptions of soil, irrigation water and rice plant in a tube-well command area and its link with iron and manganese have been analysed in various studies. The arsenic concentration is usually between 68-136 µg/L in water in 110m extensive irrigation channels, reducing the distance from the shallow tube-well point (Punshon et al., 2017). A declining trend was witnessed in the iron concentrations. Moreover, in light of the soil arsenic, the concentration of arsenic is exposed through a decreased inclination with a distance from the tube well pump. Soil arsenic was shown to be positively linked with rice grain arsenic.
Influence of pH
Azam, Sarker and Naz (2016) state that soil pH contributes to the activity of flexibility and bioavailability of arsenic. The author further states that arsenic has elevated similarity for oxide surfaces. The specificity of arsenic immersion of specific soil elements is affected by the pH and depends on the organic matter, soil texture, and the nature and parts of minerals (Mukherjee et al., 2017). Compared with other elements, which can be cadmium and zinc, the low pH of the extractant is held responsible for having low extractability of arsenic.
Bastías and Beldarrain (2016) focus on the bauxite residue (red mud) as the fine fraction excess once the arsenic extraction from the bauxite occurs through the bayer process. The author further states that the remobilisation of red mud-related arsenic V is extremely pH reliant and the accumulation of phosphate to red mud suspensions is linked to arsenic discharge for the solution.
Effects of phosphate
Kwon, Nejad and Jung (2017) view that under aerobic environments, arsenic V is known to be the key type of arsenic in soils and views with the nutrient phosphorous of plants in the form of phosphate (PV). The author further states that this aspect is not only for sorption sites on mineral sides in soil but is also applicable for root membrane transporters. Moreover, the arsenic V and PV allocate the comparable transport pathway in rice roots by inhibiting rice plants' high-similarity arsenic V/PV accretion system. This rapidly reduces to arsenic III (Suriyagoda, Dittert and Lambers, 2018).
Zecchin et al. (2017) assert that research shows that arbuscular mycorrhizal fungi (AMF) can upsurge arsenic lenience in plants. The author further states that AMF is known to reduce the proportions of inorganic and organic arsenic in rice grains. The rice injected with AMF under aerobic soils has the capability to expand the soil nutrients, which are nitrogen and phosphate. Moreover, it also helps with the growth factors, affecting the arsenic translocation to the root system. Bakhat et al. (2019) state that the effects of AMF (which are glomus geosporum and G. intraradices) on arsenic by lowland (Guangyinzhan) and upland rice were assessed in the soil. The result of this experiment was that there was a spike with and without 60mg arsenic/kg. The author further states that in arsenic-contaminated soil, Guanghizhanincoluated with G. intraradices or Handao 502 inoculated with G. geosporumimproved the acceptance of arsenic elements. There were also the AMF/rice mixtures which had striking (p<.05) roles on grain arsenic absorption (Chatterjee, Sharma and Gupta, 2017). The link between rice cultivars and mycorrhizal inoculation had significant outcomes on root biomass (p<.001), straw (p<.0001), grain yield (p<.001), grain arsenic concentration (p<.0001), root, straw and grain arsenic uptake (p<.05) showing that arsenic uptake can be restricted through the rice/AMF mixtures.
Wang et al. (2020) believe that organic material is a complicated matter of practical organic acids, which is attained from the decay of water and terrestrial plants and animals. The author adds that organic matter is robustly linked to arsenic adsorption, which depends on numerous factors of redox capability, pH, arsenic absorption and speciation, along with complexing ligands and opposing ions, aquifer mineralogical properties, and Flooding
Costa et al. (2016) mention that flooding is the main factor in arsenic uptake in rice plants. The author further states that extensive repetition of rice farming comprises endless flooding in the irrigated land. This leads to soil decreasing during cultivation, which increases the bioavailability of arsenic in the soil. The result is the accretion of arsenic in rice grains resulting in arsenic contamination. Boye, Lezama-Pacheco and Fendorf (2017) state that under the flood and aerobic environments, the dynamic of arsenic speciation in the soil solution and association arsenic build-up in rice gain and shoot in a greenhouse was analysed. The result attained by the authors was that flooding caused a rapid mobilisation of arsenic, mainly the arsenic III in the soil solution.
Moreover, in the active rice growth period, which is of 12 to 97 days, the arsenic absorption in the soil solution was seen to be 4-13 times greater under the flooded condition (He et al., 2020). It is important to note here that arsenic concentration changes according to the conditions in the soil, causing the rice plants to react accordingly in the flooded condition. There is a need for further analysis in this area that the authors have not studied.
In this study, the literature review focused on assessing arsenic in influencing the uptake in rice, along with analysing their impact on its uptake. These factors are mainly the irrigated contaminated water, as well as the soil that is used for the rice plants. The bioavailability of arsenic in the soil is another area that has been analysed in the literature review, with a specific focus on the effects of manganese and iron, the influence of pH, and the effects of phosphate, microorganisms, and organic substances. The researcher has analysed how arsenic impacts the soil content, which affects the rice plants. However, the literature gap exists in a few areas that will be analysed through this study. The first literature gap will focus on observing and evaluating arsenic's effect on rice uptake.
Oi\ice can assist in linking the gap between society and the scientific public for environmental health hazards and managing exposure to arsenic. The second literature gap in the research related to doubts in the study of inorganic arsenic in rice, along with observing the effect of arsenic on crops due to the level of arsenic growing from time to time. The researcher will focus on fulfilling the literature gaps that have been identified and provide complete research for the future purpose of other analysts.
To summarise this chapter, the developed theoretical framework consists of Nightingale’s Environmental Theory and the Theory of Pollution Policy. The employment of both of these theories for the execution of this research allows the researcher to be knowledgeable of the various processes and sources that increase the level of arsenic in the rise and determine the basic source from where an increased amount of arsenic is being added to the soil, water, and air. Both theories provide concepts that are employed to reduce the levels of arsenic uptake in rice. Furthermore, to reduce the levels of arsenic in soil, the water that is being used to irrigate the crops must be clean and pure since higher levels of arsenic in water also increases the uptake of arsenic in rice which then leads to arsenic poisoning in the individual who consumes rice with higher levels of arsenic.
Numerous developing countries, such as Bangladesh, Taiwan, and China, are using high concentrations of arsenic, despite strict limitations set by the WHO and USA food authorities to keep arsenic levels limited in food usage. Various factors are related to arsenic in influencing the uptake of rice, which also leads to having an impact on the food chain, eventually causing an influence in the uptake of rice. These factors are mainly the irrigated contaminated water and the soil elements that significantly influence the rice plants. The impact of factors has been analysed in light of the effects of manganese and iron, the influence of pH, the effects of phosphate, microorganisms, organic substances, and flooding. Each factor plays a vital role in affecting the rice plants with a high concentration of organic arsenic available in each condition.
Research methodologies are the specific procedures essential to analyse the research objectives and yield an effective result. Therefore, this chapter presents the selected tools appropriate for the study: the research design, research philosophy, research approach and method for data collection and analysis. Later, it assesses the research limitations and ethical considerations that were considered while conducting this research.
According to Pham (2018), the research philosophy is an important part of any research, which is classified into three major categories: positivism, interpretivism and realism. Moreover, these approaches are essential as they enable the researchers to decide the appropriate research approach for the research questions (Antwi and Hamza, 2015). Positivism is an approach to quantitative studies in which a hypothesis is developed, and realism analyses the experience by our senses. In contrast, interpretivism emphasizes the interpretation of research from multiple perspectives used for qualitative research (Mack, 2010).
Therefore, interpretivism philosophy was used in this research to focus on the meaning and reflect the different aspects of the topic selected for the study, i.e. arsenic in the food chain. The interpretivism research philosophy was selected for this research as, in the words of (Antwi and Hamza (2015), the philosophy is rooted in the understanding of knowledge through facts related to human behaviour. Additionally, by adopting the realist ontology, this philosophy provides multiple interpretations with a deeper level of understanding and gain of information through evaluating complexity from its unique context (Antwi and Hamza, 2015). Interpretivist research philosophy was beneficial for this research since it provides reliable information through qualitative research and explanation of the topic to a certain extent that provides a high level of validity and multiple viewpoints for the critical analysis (Pham, 2018).
Research design is broadly classified into quantitative and qualitative methods, and the selection of methods depends upon the underlying research philosophy. Quantitative research methods produce data that is always numerical to determine the impact through surveys or observational research (Jason and Glenwick, 2016; Silverman, 2016). At the same time, qualitative research methods investigate the research question through a rich and in-depth analysis that is particularly useful for exploring the “WHY” question (Hennink, Hutter and Bailey, 2020). Therefore, in this research, the qualitative method was implied to assess the data through secondary sources such as Academic Info, Google Scholar, Iseek Education, etc. The method was effective for the research to determine the different factors related to Arsenic and their impact on the food chain industry.
Moreover, according to Pathak, Jena and Kalra (2013), qualitative research is known to be multi-method as it focuses on the naturalistic and interpretive approach for data analysis. Researchers apply this method as it is extremely creative for the wide disclosure of the research topic, such as the empirical analysis from the findings of the multiple literature studies (Jason and Glenwick, 2016; Silverman, 2016). Additionally, events and factors through this method are understood more adequately, as seen in a number of contexts. Also, it is less time-consuming and cost-effective because the observer needs to analyse the existing data by understanding an idealistic or humanistic approach (Antwi and Hamza, 2015).
The two approaches of reasoning used by the researchers are inductive and deductive (Soiferman, 2010). The deductive approach begins from the general points and moves towards specifications. The arguments here are based on the rules, laws or principles that are accepted widely. Whereas the inductive method of reasoning moves from specific to general, the arguments here depend upon observation and experiences (Soiferman, 2010). Deductive is a top-down approach; however, inductive is a bottom-up approach as this research has been conducted through qualitative methods. Therefore the approach selected for the study was inductive, in which themes are broadly interconnected to generate a theory for the aim of the research (Zalaghi and Khazaei, 2016).
Inductive reasoning was beneficial for the research as it detects patterns and explores the research questions in a more open-ended way which, especially at the beginning of the research, is helpful for the broad exploration of the topic (Armat et al., 2018). Furthermore, the learners are benefited from this approach as it involves learning through rules of generalisation and becomes more interesting when the topic is viewed from different experiences (Soiferman, 2010). The biggest advantage is that by using inductive reasoning, the researcher gets to work with the various probabilities, and an idea regarding the research is developed at the starting point, which provides a better understanding of the topic (Zalaghi and Khazaei, 2016). In this study, the inductive approach was used.
The data in this research was collected through secondary sources, which are readily available and collected from various sources. Moreover, secondary data was used in this research as, according to Trinh (2018), this type of data is obtained more quickly, and it is economical, saving expenses and extra effort. In this study, the data was collected from previously published studies on arsenic in the food chain and the factors influencing the uptake of rice. Moreover, according to Johnston (2017), secondary data is effective as it helps to make the collection of primary data more specific such that it enables the researcher to find out the literature gap and other deficiencies in the existing literature to improve the understanding of the research problem. Therefore, it was selected for this research to evaluate the current data and compare the existing literature and their results (Johnston, 2017). In addition, since the data collected through primary sources is already stored in electronic format, the researcher gets more time to analyse the data instead of preparing it for their research. Secondary data also offers a level of expertise and professionalism in exploring the current changes and trends within the research topic (Trinh, 2018).
The key search terms were Arsenic, soil contamination, uptake of rice and food chain.
Inclusion and Exclusion Criteria etc.
The data has been included from the Cochrane database of systematic reviews comprised of literature from the National Health Service, National Library of Medicine, Science Direct, PubMed, and Central. Moreover, the data was selected from the last 10 years, whereas the data published before 2010 was excluded from the systematic review. Additionally, the articles that were available in the full text were found eligible for the research.
The data in this research has been analysed through the content analysis tool, which was beneficial for evaluating certain themes, words, or concepts from the data collected through secondary sources (Vaismoradi et al., 2016). Moreover, using content analysis, researchers can analyse the meanings, relationships and influence of the factors determined during the data collection for the research. Content analysis was extremely useful for this research as it provided valuable insights through the analysis of results of the previous studies (Vaismoradi et al., 2016).
Additionally, it allows the researcher to study human thoughts and analyse complex thoughts related to the research aims by providing pieces of evidence from multiple perspectives (Erlingsson and Brysiewicz, 2017). Content analysis is a tool for transparent research. Using this method, the researcher can follow up the study in feasible ways and set out the results examined for the research purpose. Furthermore, content analysis allows a certain amount of longitudinal analysis and involves no reactivity, which allows the information to be studied from various contexts (Erlingsson and Brysiewicz, 2017).
Ethical considerations are specified as one of the essential parts while the research is carried out. The research has ensured the follow-up of all the principles and rules during the execution of the study according to the ethical considerations for the secondary data collection. All the data employed for the research has been cited properly with the name and year of the research; also, proper referencing has been done in which the respective authors were credited for their work in accordance with the style of referencing suggested by the school. Additionally, the results of the multiple research are mentioned as identified by the studies' authors accurately.
The research was limited to qualitative research as the data was collected only from secondary sources. Additionally, the research has evaluated the multiple perspectives of the researcher through previously published articles. The study was limited to the analysis of Arsenic only and its influence on the uptake of rice, whereas it could be explored in a number of food chains other than rice.
This chapter has analysed the research method and approach used for this study to explore the impact of arsenic contamination in food chains and the factors related to Arsenic that influence the uptake in rice. The research philosophy that was used in this study was interpretivism which was effective here as it analysed the data collected through secondary sources. Moreover, the qualitative research method was used by collecting the data through published research articles and official websites of the health and food sectors. Furthermore, the data collected was analysed with content analysis to explore the themes in the research. Lastly, the ethical considerations while conducting the study were discussed, followed by research limitations.
In this chapter of the study, the findings and discussion of the study will be analysed. The findings section will focus on critically analysing the research objectives. These objectives are assessing the challenges in the food chain due to arsenic contamination, analysing the arsenic's role in the contamination of soil, evaluating the impact of arsenic in the food chain, and assessing the factors related to arsenic that influence the uptake in rice. The discussion section will compare and contrast the information attained from the literature review and the findings section related to each objective. The researcher would then provide his opinion regarding each of the objectives in the discussion section. The chapter will conclude by providing an overview of all the information attained within this chapter.
According to Ghosh et al. (2012), arsenic is a chemical component found in groundwater and is considered a vital source for contaminating drinking water. The research identified that arsenic is a highly toxic chemical substance that raised a considerable number of challenges in the food chain (Ghosh et al. 2012). The research of Schmidt (2015) indicated that water is primarily the substance that is affected by this highly toxic element that consequently affects the farmer involved in irrigation and other agricultural functions. Furthermore, one of the challenges in the food chain due to the presence of arsenic water is when the contaminated water is used for irrigation, it makes the soil toxic. It affects the quality of plants which are consumed by humans and animals and causes harmful respiratory diseases and diabetes (Kabay et al., 2019). The study of Thakur, Gupta and Chattopadhyay (2013) contemplated that one of the major challenges caused by arsenic in a food chain is contaminating the ground and surface water, which leads to the formation of major diseases in humans such as cancer and stroke. Additionally, the prevalence of arsenic has also been identified in the activity of agriculture where the contaminated water is used for irrigating soil and growing crops that, consequently, affects the quality of crops by making it toxic, which, when consumed by humans, causes the heart diseases like hypertension (Thakur, Gupta and Chattopadhyay, 2013). Similarly, (Singh, 2015; Masuda 2018) stated that arsenic is naturally present in the crust of the earth and contaminate the surrounding water that can be utilised by humans for agricultural purpose, drinking water or can be consumed by aquatic animals (Fig.2). Thus, it raises a huge challenge in the food chain that further raises the long-term challenges pertaining to the health of living things .
–Mechanism of Arsenic contamination cycle in surface and groundwater
Nachman et al. (2018), the author highlighted that almost every crop needs water to grow. Some of the most common food samples include rice, wheat and maize, which are major food chain elements. Nachman et al. (2018) added that when toxic water is being used in the growth of such crops that are widely consumed, it creates a threat to the whole food chain. In contrast, Dahlawi et al. (2018) identified that vegetables are also major determinants of a food chain, including carrots, lentils, beans, tomatoes, potatoes and more; humans and animals widely eat these vegetables. Arsenic primarily creates toxicity during the growth of such vegetables by using contaminated water from the sea, affecting the whole food chain upon consumption (Dahlawi et al. 2018). According to Kabay et al. (2019), ingesting arsenic-contaminated groundwater has been a major challenge of arsenic poisoning in the food chain. A similar author indicated that major countries affected by arsenic-contaminated groundwater are India, Bangladesh and West Bengal (Kabay et al. 2019).
The research of Ghosh et al. (2012) highlighted that in terms of groundwater, wells in almost 60 out of 64 districts of India have a high concentration of arsenic toxicity that is far more than the limit prescribed by the World Health Organisation (WHO). The severity of arsenic toxicity in an extensive number of wells creates a life-threatening challenge for the residents of India, Bangladesh and West Bengal, as they are the primary entity being exposed to arsenic toxicity through the drinking water of wells (Thakur, Gupta and Chattopadhyay, 2013). Molin et al. (2015) asserted that one of the most common threats of arsenic in food chain is using the water used for growing and cooking rice, which can cause lung, skin, bladder and liver disease among humans. Whereas the research of Shri et al. (2019) identified that high levels of challenges arose in drinking water due to arsenic toxicity that is used in growing multiple plants and fruits such as bananas, mango and jackfruit humans consume.
According to Srivastava et al. (2015), the major problem these days is arsenic contamination; the level of the contaminant has spread widely over the sediments and the soil from the other natural resources and the groundwater, which is affecting a number of people indirectly or directly with its large area coverage. However, Srivastava et al. (2015) also stated that many people know that Arsenic is poisoning the groundwater. However, the consequences of soil contamination are still unknown in many parts of the world, specific to the people of countries where the soil contamination is huge due to arsenic. Similarly, in the report of WHO (2020), it is explained that the elevated levels of arsenic contaminating the soil create long-term exposure from industrial processes, smoking tobacco the hazardous waste materials and eating contaminated food, and the presence in groundwater is hugely affecting the countries such as Chile, Argentina, China, Mexico, Bangladesh, the USA and India.
Furthermore, according to Abbas et al. (2018), natural processes also inject Arsenic into the soil, such as volcanic activity and weathering of minerals rich in Arsenic in the critical zone of Earth due to more than 200 minerals in the crust of the Earth abundance of Arsenic is abundant. Similarly, as mentioned in the report of WHO (2020), Arsenic is also an alloying agent in the processing of textiles, pigments, paper, glass, metal adhesives and ammunition. In the research of Abbas et al. (2018), the ingression of Arsenic into the environment is via anthropogenic activities such as smelting, mining, the use of wood preservatives and Arsenic-based fertilizers, excessive use of pesticides made from Arsenic and irrigation from the Arsenic-contaminated groundwater. In addition, the treatment of tobacco plants with lead arsenate insecticide and the plants also take it naturally from the soil, which makes tobacco smoking injurious to health (WHO, 2020).
Additionally, Srivastava et al. (2015) highlighted that arsenic poisoning the soil means it affects the vegetables and crops too. Even the physical and chemical methods used to reduce Arsenic's effects produce toxic sludge, which is also very dangerous to human life. Furthermore, as mentioned in the report of DHSS (2020), the white metallic or silver-grey solid element, i.e. Arsenic, after combining with other inorganic and organic materials, become more toxic and contaminate the soil. The higher chance of Arsenic exposure is in the areas used for processing ore, farming or tanning hides (DHSS, 2020). Moreover, Srivastava et al. (2013) analysed that the long-term and excessive accumulation of Arsenic in the soil exert land degradation and cause a crop production disease which is about empty panicle in rice named “straighthead disease”.
Moreover, Abbas et al. (2018) investigated the toxicity of carcinogenic Arsenic and identified that soil contamination had become a global health, environmental and agricultural issue. Even the low concentration of Arsenic exposure to plants causes many physiological, morphological and biochemical changes which damage the plants and animals. Arsenic and its compounds are ranked as the Group 1 human carcinogen by IARC (International Agency for Research on Cancer), and also it is ranked among the 20 most hazardous substances. According to Pandey et al. (2018), various methods have been developed to remediate contaminated soil, such as chemical oxidation, physical excavation, extraction techniques, soil solidification, etc. However, reducing the harmful effects still affects people from various sources, especially those found in water, such as seafood (WHO, 2020). Furthermore, as highlighted in the research of Srivastava et al. (2013), the assessment of soil contamination can be done by focusing on future R&D speciation and transformation of arsenic in soil and its related properties, which are hazardous to the agriculture and food chain industry.
A known fact is that arsenic presence in the food chains causes significant damage in every area of the ecosystem (Wang et al., 2015). However, Basu et al. (2015) believe that if arsenic usage is controlled within the food chain, it will not cause as much harm to the ecosystem as it is known for. There are diverse kinds of safe drinking-water techniques that can be implemented to ensure that the arsenic content is decreased. Mitigation techniques or looking for alternative sources of water can be considered as some of the ways to help out the countries that have a high presence of arsenic in their water (Kumar et al., 2015). Mitra et al. (2017) state that the major source through which arsenic enters the food chain is water. Therefore, there is a major need to ensure that the arsenic content is reduced in water in some ways. For this, Lindsay and Maathuis (2017) state that certain short-term and long-term measures can be implemented by the countries that are facing the high arsenic content issue.
The author further cites that short-term actions can be to decrease arsenic-exposure risks, which comprise the use of rainwater for drinking during the wet season, along with changing cooking habits and making use of applications of arsenic removal devices. However, Ashraf et al. (2015) do not agree with these steps. The author believes that not every developing country can follow this procedure due to financial constraints. For these developing nations, the continued use of arsenic in the food chain is not considered a major health issue. They believe that it does not harm health in any way. At this point, Singh (2015) states that if the developing nations cannot implement short-term measures to deal with the impact of arsenic in the food chain, which causes severe health issues, these nations can opt for long-term solutions, which might take time but it would help in decreasing the impact of arsenic in the food chain. These effective long-term solutions can work with the government to create concerted actions. These actions would need to be based on a solid knowledge of location conditions which would comprise working with the communities.
Moreover, there would also be a need for having systematic information management systems with partners in all sectors that are linked with the water supply, both agricultural and public health (Lin et al., 2018). Zhao and Wang (2020) do not agree with this notion as he believes that arsenic cannot be decreased from the food chain because apart from water, the soil is another area with a high content of arsenic. The author believes that decreasing the arsenic in the soil would require extensive filtering in various ways, as fertilisers, desiccants, and pesticides contribute to the rise of arsenic. Moreover, adding to these fertilisers, the irrigation water comprising high arsenic content would increase the content significantly in the food chain causing major risks for the entire system (Wang et al., 2015). Carlin et al. (2016) state that the impact of arsenic in the food chain can be controlled; however, the measures that need to be taken for it are expensive for most developing countries, such as Taiwan and Bangladesh. There is a need for developed countries like China and India to come up with solutions to help out developing nations with this specific issue.
Hussain and Farooqi (2018) state that the effect of manganese and iron is considered to be playing a major role related to arsenic which eventually influences the uptake in rice is not true. The author believes that there are contrasting studies which state that manganese and iron do not contribute to arsenic impact in the uptake of rice. The major reason here is that there are different forms of soil which play a role in creating such conditions, due to which manganese and iron come into play. Srivastava et al. (2016) believe that there is a relationship between the amount of one element to another which can be considered as the absolute level that creates the condition for the influence of arsenic to occur. The author further cites that there is a need for further studies to be carried out to assess the situations that ensure that manganese and iron influence rice uptake, as the present studies are just focused on the acidic conditions created due to the presence of arsenic.
Zecchin et al. (2017) are of the view that arsenic-contaminated water is a major issue that needs to be resolved on an immediate basis. The author is of the view that in such a situation, it is important to analyse the way pH is having an impact on the arsenic aspect that leads to an impact on the uptake of rice. The pH level was adjusted to see how it impacted the arsenic, which was done through the arsenate stock solution created by liquefying arsenate in deionized water with 99% cleanliness. The compulsory concentration was attained through the diluting stock solution. This notion is supported by Srivastava, Suprasanna and Tripathi (2020), who states that adjusting pH requires a pH meter of 0.1 N sulfuric acid or 0.1 N sodium hydroxide solutions. The experiment was then carried out through five variables: pH of the solution, adsorbent dosage, contact time, initial concentration of arsenic and temperature. The result was that there was an increase in the removal efficiency of arsenic. It cannot be said with certainty how efficient the removal was, but it has been reported that, to a certain extent, it has been made possible
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Kerl et al. (2018) believe that phosphorus is considered a key element for plant growth, but its impact is seen to be of different types on arsenic influence in the uptake of rice. The author further states that the outcome of phosphate on the sorption/desorption of arsenic in the soil environment is mainly used as a form of crop fertiliser because of its effect. However, Iqbal et al. (2019) cite that the bioavailable fraction of arsenic in soils to crop plants depends on the soil's various physical and chemical properties. It is important that these properties are considered before it can be assessed if the extraction of arsenic can be carried out easily or not. Xu et al. (2019) further criticise the notion by citing that large additions to phosphate are relevant to high anion-fixing soils or even alkaline pH or Fe and AI oxide that could impact the solubility of arsenic. At the same time, it should be noted that arsenic sensitivity is linked with phosphate nutrition in plants. Once the intracellular phosphate levels are increased, it would help make the rice seedling resistant to the effects of arsenic. This is an area that many developing countries need to focus on.
Panthri and Gupta (2019) state that microorganisms tend to have a diverse impact on the arsenic that influences the uptake in rice. The author mentions in his study that the idea was to analyse the impact of using various microorganisms on the uptake in rice. It was revealed that two types of bacteria species worked towards protecting the rice plants when they were under attack. The root target for the microbes was that they would reside in the rhizosphere, which is the soil around the plant robes. According to Mondal et al. (2019), the idea of having microorganisms defending the plant from the rice blast fungus worked in favour of the rice as it helped prevent any kind of adverse reaction on the rice. However, Kalita et al. (2018) believe that more than protecting the plant, it was important to mobilise the iron plaque that tends to accumulate at the base of plants which is the area where arsenic is present in. The microbe, EA106, is considered to be extremely effective in this aspect as it effectively prevents the poison from reaching the plants and making it useless from being used.
Kwon, Nejad and Jung (2017) mention in their study that organic matter tends to have diverse impacts on the arsenic in the soils, affecting rice uptake. The idea here is to analyse how organic matter tends to decrease the arsenic, irrespective of the source from which the organic matter has come. The author believes that farmyard manure was the main source in his study that helped him analyse the decrease of arsenic in the soil. However, Cui et al. (2019) cite that apart from farmyard manure, vermicompost was also an organic matter that significantly influenced decreasing arsenic. At this point, the author further cites that the treatment used to decrease arsenic was not a vital factor because he had not used the treatment on some arsenic soils in some areas of his experiment. He had just applied the vermicompost, which worked its way through cutting the arsenic in the soil and decreased the satisfaction of the element significantly. It can be considered one of the ways to prevent the rise of arsenic in rice plants.
Flooding occurs in the rice plants' soil due to climate change, which is considered a major hindrance to plant growth and performance, as per Gustave et al. (2019). The author further mentions in his study that any form of increased atmospheric carbon dioxide and temperature would adversely impact plant growth and performance. If there is an increased atmospheric carbon dioxide, it will stimulate the photosynthetic rate of rice, which would also increase the water and nutrient use of the photosynthetic product. This eventually causes the biomass to increase, along with yields. However, Afzal, Hussain and Farooqi (2018) believe that flooding is focused on inducing the reductive dissolution of iron oxyhydroxide minerals and reducing the arsenic adsorbed on soil minerals. This increases the dissolved concentrations and the availability of arsenic as well. Therefore, it is important to understand that there need to be preventive measures to ensure that flooding is prevented from taking place (Gharachorloo et al., 2019; Bakhat et al., 2019). Zhang et al. (2020) cite that draining the water is not an option that can be considered here as this would deprive the plant of numerous essential nutrients vital for its growth and development.
The study's primary objective is to identify the challenges associated with the food chain due to the presence of arsenic. The studies of Afzal, Hussain and Farooqi (2018); Bakhat et al. (2017) indicated that the major challenge in a food chain is the presence of arsenic in drinking water, which creates a threat to all the living thing that consumes the drinking water. Similarly, the research of Thakur, Gupta and Chattopadhyay (2013); Singh (2015); Nachman et al. (2018) in content analysis indicated that arsenic-contaminated drinking water is one of the major challenges of arsenic in the food chain as it affects the health of entities consuming contaminated water with arsenic toxicity. Health threats such as cancer and respiratory diseases are commonly caused by arsenic toxicity (Ghosh et al. 2012). Additionally, the research of Awasthi et al. (2017) in literature contemplated that inorganic composites of arsenic are sodium arsenite, arsenic trioxide, arsenic acid and arsenates, arsenic trichloride, and arsenic pentoxide, which are lead and calcium arsenates that impose a serious threat on the health of humans.
The studies of Kumarathilaka et al. (2018) from literature considered food as a major determinant of arsenic toxicity among humans. A similar author added that contaminated food had been used in irrigation and agriculture of highly consumed food by humans and animals, which consequently creates a challenge in the food chain due to increased toxicity. Similarly, the research of Dahlawi et al. 2018; Kabay et al. (2019) from content stated that arsenic found in groundwater had been utilised in the irrigation of crops that makes multiple fruits, vegetables and cereals toxic due to which the health of entire food chain is exposed to a risk of severe long-term diseases. Furthermore, the studies of Majumdar, Kumar and Bose (2020) from literature regarded that the primary challenge caused by arsenic is contaminating the groundwater, which is a primary source of water consumption in multiple nations. Thus, it exposes those individuals to arsenic toxicity and affects the food chain. Whereas the studies of Ghosh et al. (2012); Molin et al. (2015) in content analysis highlighted that drinking water is used for irrigating soil and growing crops that, consequently, affects humans' health when consumed as a food.
Arsenic is considered the element that naturally causes soil contamination, used in both inorganic and organic forms. Additionally, significant inorganic arsenic composites are used in many agricultural processes, such as arsenic trioxide, arsenic pentoxide, sodium arsenite, etc. (Awasthi et al., 2017). Furthermore, fish's organoarsenicals, which comprise dimethloxyarsylethanol, arsenocholine, and trimethylarsonium lactate, contaminate the water and affect the sealife; however; the impact of methylarsonic and dimethylarsinic acids is low (Afzal, Hussain and Farooqi, 2018).
Similarly, it has been evaluated in the research findings that the excessive accumulation of Arsenic in the soil cause empty panicle in rice and a straighthead disease in crops (Srivastava et al., 2013). Further, the consumption in low amounts affects the plants by exposure to Arsenic through soil contamination from biochemical or morphological changes (Srivastava et al., 2015). The role of Arsenic in poisoning groundwater has harmful consequences. The elevated levels of Arsenic contaminate the soil through industrial processes, and tobacco plants are the main causes of Arsenic exposure to groundwater (Abbas et al., 2018). Moreover, the study also analysed that the countries such as China, Bangladesh, Mexico, India, etc., have huge contaminated lands due to natural and man-made processes (WHO, 2020). Further, it has been investigated that the volcanic activities, the mineral weathering, mining and smelting processes cause the ingression of Arsenic into the soil and contaminate it through its carcinogenic characteristics.
Arsenic also impacts the soil by using fertilizers, pesticides and wood preservatives which have huge amounts of lead arsenate. The areas near such industries suffer from deadly diseases that can be due to breathing near contaminated soil (Abbas et al., 2018). However, some processes are developed to reduce the impact of arsenic in affecting the soil, such as physical excavation, extraction techniques, chemical oxidation, soil solidification, R&D methods, etc. (Srivastava et al., 2013).
The impact of various factors of bioavailability/soil concentrations plays the main role in the uptake of rice. The main impacts that would be analysed are from the point of the effect of manganese and iron, the influence of pH, the effect of phosphate, microorganisms, organic substances, and flooding. Bakhat et al. (2017) state in their study that manganese and iron precipitate as iron and manganese oxides in a toxic atmosphere. The author further states that there is a rising similarity between iron and manganese oxides and arsenic, along with residue redox possible. The firmness of iron and iron (hydr)oxides mainly depends on the pH of the deposit. Azam, Sarker and Naz (2016) state that the pH of the soil contributes to the activity of flexibility and bioavailability of arsenic. The author further states that arsenic has elevated similarity for oxide surfaces. Kwon, Nejad and Jung (2017) believe that under aerobic environments, arsenic V is known to be the key type of arsenic in soils and views with the nutrient phosphorous of the plant in the form of phosphate (PV). Zecchin et al. (2017) assert that research shows that arbuscular mycorrhizal fungi (AMF) can upsurge arsenic lenience in plants. Wang et al. (2020) believe that organic material is a complicated matter of practical organic acids, which is attained from the decay of water and terrestrial plants and animals. Costa et al. (2016) mention that flooding is the main factor in arsenic uptake in rice plants. The author further states that extensive repetition of rice farming comprises endless flooding in the irrigated land.
In contrast to the above findings, various authors have stated that each of the factors tends to have a different impact on the role of arsenic in the influence of uptake in rice. For instance, Cui et al. (2019) cite that apart from farmyard manure, vermicompost was also an organic matter that significantly influenced decreasing arsenic. At this point, the author further cites that the treatment used to decrease arsenic was not a vital factor because he had not used the treatment on some arsenic soils in some areas of his experiment. In relation to the pH, Srivastava, Suprasanna and Tripathi (2020) state that adjusting pH through the use of a pH meter of 0.1 N sulfuric acid or 0.1 N sodium hydroxide solutions. The experiment was then carried out through five variables: pH of the solution, adsorbent dosage, contact time, initial concentration of arsenic and temperature. The result was that there was an increase in the removal efficiency of arsenic. It cannot be said with certainty how efficient the removal was, but it has been reported that it has been made possible to a certain extent.
Bakhat et al. (2019) are of the view that combined evidence proves that high rice product nations, which are India, Bangladesh, Taiwan, and China, tend to exceed the usual absorption of arsenic in soil (10.0 mg/kg) and the extreme standard allowed by the United States Environmental Protection Agency which is 20.0mg/kg. In China and Taiwan, the organic arsenic composite roxarsone exists in poultry brood which is usually utilised as a fertiliser for rice that is at sea-level rice, which the plants immerse. Chatterjee, Sharma and Gupta (2017) believe that rice grain yield is decreased by arsenic absorption of the soil where the limit of the roxarsone/kg soil which killed rice plant was 200mg. It can be seen clearly that the arsenic absorption in the rice grain surpassed the statutory acceptable limit that has been set by the WHO (Wang et al., 2020).
Basu et al. (2015) believe that if arsenic usage is controlled within the food chain, it will not cause as much harm to the ecosystem as it is known for. There are diverse kinds of safe drinking-water techniques that can be implemented to ensure that the arsenic content is decreased. Mitigation techniques or looking for alternative sources of water can be considered to help countries with a high presence of arsenic in their water (Kumar et al., 2015). Mitra et al. (2017) state that the major source through which arsenic enters the food chain is water. Therefore, there is a major need to ensure that the arsenic content is reduced in water in some ways.
It can be observed from the above findings that although arsenic is an element that cannot be extracted completely from the water system, certain measures can be taken to ensure that arsenic element is controlled in the rice plants, which would prevent any further damage to the food chain. The idea here is that developing countries need to take appropriate measures to ensure that they are working towards finding a solution to help them with this specific cause.
In this chapter, the findings and discussion have been carried out in relation to the aim and objective of the study. It has been revealed through the findings that the presence of arsenic in the food chain is a vital element that cannot be completely eradicated; however, some measures can be taken to ensure that it is controlled and the impact of it is as less as possible on the food chain. From the discussion, it has been analysed that although arsenic cannot be removed, there is a need for developing countries to ensure that they are taking measures to implement various ways to mitigate the presence of the arsenic element. This would help them to ensure that any adverse impact of arsenic on the food chain is as minimal as possible, as well as has a minimum negative impact on the entire ecosystem comprising animals, plants and human lives.
Arsenic is a toxic material for humans, animals and plants, and its harsh consequences are increasing because of its use in large amounts in soil and food. Some anthropogenic activities and mining release it into the soil and through irrigation, where contaminated water is used (Li et al., 2014). The increased uptake of arsenic in rice and its adverse health effects made the topic of research significant. Therefore, to contribute to the research, this study was carried out to identify the factors that influence the uptake of arsenic in rice. The research was conducted to explore the challenges on the food chain due to Arsenic, to assess the role of arsenic in soil contamination, to analyse the impact of arsenic in the food chain and identify the factors related to arsenic that influence the uptake in rice. This research has been conducted through content analysis and a systematic review of the previously published studies.
This chapter of the research has assessed the summary of the findings by analysing each objective. Further, the chapter presented recommendations in order to reduce the Arsenic in the food chain that influences the uptake of rice. Lastly, it explained the future implications of the research and the conclusion for the topic of the study.
The research has analysed the challenges of arsenic associated with the food chain. It was identified that the major challenge is the presence of Arsenic in the drinking water, which is a threat to human lives as the hazardous material causes harmful diseases. Additionally, it was also investigated in the research findings that the toxic Arsenic compounds affect human life by affecting the crops and animals; this is a crucial challenge in the food chain. Similarly, arsenic is found in abundance in groundwater. It is excessively used in the irrigation of crops, which makes the fruits and vegetables toxic, and this exposure is a risk of causing severe and long-term diseases to humans, being a challenge for the food chain. Another primary challenge that arose from Arsenic was determined in the residents of West Bengal, India and Bangladesh as they drink water from the wells. Also, the threat to the food chain is due to the growing use of rice, which increases skin, lung and bladder diseases.
The second research objective was to examine Arsenic's role in soil contamination and has identified that Arsenic, in combination with organic and inorganic materials, contaminate the soil. Further, Arsenic contaminates the soil in the form of many harmful combinations, such as the organoarsenicals comprising dimethloxyarsylethanol, arsenocholine, and trimethylarsonium lactate affecting water through the sea. In contrast, inorganic composites of arsenic are sodium arsenite, arsenic trioxide, arsenic acid and arsenates, arsenic trichloride, and arsenic pentoxide, which contaminate the soil and affects the lives of human. Further, Arsenic contaminates the groundwater, and through soil contamination, the level of contaminants is also increased due to the exposure of Arsenic to natural resources. Industries also produce Arsenic and greatly affect soil contamination by using it to develop metal adhesives, pigments, paper, glass, etc. It has also been explored in the research findings that Arsenic causes soil contamination from the anthropogenic activities, processing ore, farming or tanning hides, weathering of minerals and some natural processes such as volcanic activity.
The impact of arsenic on the food chain was analysed in the research findings. It was identified that the ecosystem is affected by the presence of arsenic in the food chains. If the usage of arsenic is reduced, there will be control over a number of harmful consequences of arsenic consumption. The vital aspect affecting arsenic availability in food chains includes the organic carbon content, ionic robustness of the soil solution, pH, cation conversation capacity and iron oxides. Another factor that influences arsenic uptake in rice is the bioavailability of arsenic present in the soil.
Further, many short-term and long-term techniques can be used as safety measures for the high use of arsenic faced by many countries in the world, especially in the food chain industry. Additionally, the government can take action against the excessive use of arsenic in multiple industries; they can integrate it by collaborating with communities and introducing solid knowledge about arsenic. The partnerships with all sectors associated with agricultural, water and public health sectors can also take some efficient measures for reducing the effects of arsenic in the food chain.
The last objective of the research was to assess the factors related to arsenic that influence the uptake in rice. The main factors determined from the research findings are the influence of pH, the effect of manganese and iron, the effect of phosphate, organic substances, microorganisms and flooding. It was investigated that the iron and manganese oxides are toxic to the atmosphere and are similar to arsenic. Iron and manganese decrease the flexibility of arsenic in the deep soil horizons, which leads to the growing arsenic in topsoil. Moreover, the pH of the soil actively participates in the bioavailability of arsenic and has elevated similarity on the oxide surfaces. Low pH is responsible for the arsenic's low extractability compared to other elements such as zinc and cadmium.
Furthermore, the arsenic V and PV allocate the comparable transport pathway in rice roots which are the key types of arsenic in soils with the nutrient phosphorus. Arbuscular mycorrhizal fungi (AMF), a microorganism, are known to reduce the rice grains' organic and inorganic proportion gain. It was evaluated that flooding is also a main factor in arsenic uptake in rice plants due to the excessive repetition of rice farming in irrigated land.
By examining the analysis, it has been found that major challenges of arsenic in the food chain include contaminated drinking water and arsenic toxicity in irrigation and agriculture due to unhealthy groundwater. It has also been found that multiple food substances such as rice, maize and wheat are affected with arsenic toxicity during growth and irrigation, which seriously threaten human health. In light of the above analysis, it is recommended that training on discriminating high-arsenic and low-arsenic sources must be given to farmers to that the contaminated food and drinking water do not reach the final consumer in the food chain. Furthermore, actions like blending low-arsenic water with high-arsenic water to get to acceptable concentration level of arsenic must be taken to minimise the threat to the food chain. Lastly, an arsenic removal system must be installed at multiple places so that the arsenic toxicity can be minimised to a possible extent that does not impose a higher risk on the health of people
The current study aimed to identify the role of arsenic in affecting the food chain. The study would be primarily helpful for multiple governments, as it recommends multiple ways to control the damage of arsenic on food substances. Additionally, the current research would assist the people working in the agricultural sector to take necessary steps for minimising arsenic toxicity in irrigation and growing crops. Furthermore, the current study would facilitate rice consumers, highlighting the process by which the soil gets affected by arsenic toxicity and suggesting measures for reducing soil contamination so that the consumers can uptake the rice. In addition, the current study would encourage multiple health regularities for installing an arsenic removal system at places with a high risk of consuming food that is affected by arsenic toxicity. Similarly, the current study would promote various governments for providing training to farmers and multiple professionals involved in irrigation and agriculture for discriminating high-arsenic and low-arsenic sources at places with high arsenic toxicity.
Moreover, the current research would help initiate the practice of blending low-arsenic water with high-arsenic water in order to get to an acceptable concentration level of arsenic that could possibly reduce the level of arsenic in a nation like Bangladesh, India and West Bengal, where the rice is extensively consumed, and groundwater have a high toxicity level of arsenic. The current research can also be used by future researchers interested in studying the similar phenomena and want to contribute to increasing the literature related to arsenic contamination. Additionally, the current study would assist WHO and other health regularities in increasing awareness of potential damage caused by arsenic like chemical substances and the risk it would create to people's health.
The current study aimed to identify the role of arsenic in the food chain and the factors influencing the rise. Additionally, the current research highlighted the challenges in the food chain due to the presence of arsenic. Furthermore, the study analysed the role of arsenic in the contamination of soil, followed by the impact of arsenic in the food chain and identified the factors related to arsenic that influence the uptake in rice. The current study considered Nightingale’s Environmental Theory and The Theory of Pollution Policy to conceptualise arsenic's environmental effect in multiple nations. In addition, the study highlighted the factors related to arsenic that influence the uptake of rice, which was identified as groundwater irrigation. As the nature of the current study is highly critical, the study employed a content analysis technique for analysing the authentic data from secondary sources such as journals, articles, and books.
After examining the data, the study found that irrigation and agriculture are major areas with a prominent risk of arsenic toxicity in the food chain. Additionally, the consumption of contaminated drinking water is also evaluated as a primary source that raises a challenge on the food chain due to the high concentration of arsenic. Furthermore, the study identified that contaminated water used on soil is a major source of contaminating soil that affects the health of humans by touching, digging and eating the soil, which increases the chance of causing harmful skin, liver and respiratory diseases among humans. Similarly, the study also found that the factors that influence arsenic accumulated in rice grains are plant physiology, method of processing rice and type of rice cultivar. Lastly, the study evaluated that brown rice accounted more for arsenic toxicity than white rice. After analysing the findings, the study presented brief recommendations which were training on discriminating high-arsenic and low-arsenic sources that must be provided to farmers who can prevent the contaminated food and water from reaching the final consumer. Moreover, another recommendation was to promote the practice of blending low-arsenic water with high-arsenic water in order to get an acceptable concentration level of arsenic. At the same time, the final recommendation was to install the arsenic removal system at necessary places to minimise the risk of arsenic toxicity on human health.
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