Heavy metals and metalloids accumulation in common beans (Phaseolus vulgaris L.): A review (2023)

The presence of heavy metals (HMs) and metalloids (Ms) is one of the major environmental and food safety concerns due to potential hazards to human health. Arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) pose major public health concerns due to their elevated levels of toxicity. For example, organic species of As are considered to be less toxic than inorganic arsenic compounds (Rosas-Castor et al., 2014). The most toxic form of Cd is the divalent cadmium ion (Cd²⁺) (Loredana Ungureanu and Mustatea, 2022). For Hg, the organic species methylmercury, CH₃Hg⁺, is the most toxic and bioavailable Hg species to humans (Ullrich et al., 2001). Organic forms of lead have been reported to be more harmful than inorganic forms (Rahman and Singh, 2019). Table 1 shows the lethal doses (LD₅₀) for some inorganic and organic species of HMs and Ms. The literature reports the effects of heavy metals and metalloids, and their species on human health, such as skin lesions, tremors, mood changes, cancers, as well as respiratory, gastrointestinal, cardiovascular, neurological, reproductive, renal, and hepatic effects (ATSDR, 1992; ATSDR, 1989; WHO, 2018; WHO, 2021; WHO, 2021; Beckers and Rinklebe, 2017; Flora, 2015; Teixeira et al., 2018).

As, Cd, Hg, and Pb naturally occur in the environment at low concentrations, mg kg^−1, and μg L⁻¹ in soil and water, respectively (ATSDR, 2007; ATSDR, 2012; ATSDR, 2020; ATSDR, 2022). Table 2 shows USEPA (United States Environmental Protection Agency) and WHO (World Health Organization) approved limits for these elements in water and soil. The sources of metal and metalloid contaminants are natural, such as volcanic eruptions, wildfires, and erosion processes, or anthropogenic sources, such as coal burning, mining and smelting operations, waste incineration, oil burning combustion, pesticide application, and phosphate fertilizers (He et al., 2019; ATSDR, 2007; ATSDR, 2012; ATSDR, 2020; ATSDR, 2022; Thompson and Bannigan, 2008). Table 3 shows the global heavy metal and metalloid content. Increased concentrations of these elements (As, Cd, Hg, and Pb) in contaminated areas have been described by different pathways in water and soil worldwide and exceed established limits. In countries such as Mexico, Iran, Brazil, Turkey, India, and South Korea, the concentrations of As in groundwater and soil exceeded USEPA limits: 10 μg L⁻¹ and 20 mg kg⁻¹, respectively (Table 3), which Indicates a serious worldwide pollution problem, increasing the risk of humans being exposed to these elements through ingestion of water and inhalation of dust. Polluted areas in countries such as India, Iran, China, and Georgia have exceeded the Cd limits set by the USEPA, 5 μg L⁻¹ and 3 mg kg⁻¹ for drinking water and agricultural soil, respectively (Panwar and Ahmed, 2018; Qasemi et al., 2019; Idrees et al., 2018). Mercury levels in groundwater in India (Kumar et al., 2019), Nigeria (Chinye-Ikejiunor et al., 2021), and Mexico (Mendoza-Lagunas et al., 2019) were determined to exceed USEPA limit of 2 μg L⁻¹ while on the soil in Mexico, Switzerland, and Spain exceeded the USEPA limit of 23 mg kg⁻¹ for residential soils (Quintanilla-Villanueva et al., 2020; Frossard et al., 2018; Campos et al., 2018; Fernández-Martínez et al., 2019). Lead has been measured in the water and soil of contaminated areas of Mexico, Bangladesh, Iran, China, and India (Bhuyan et al., 2019; Bhuiyan et al., 2010; Gamiño-Gutiérrez et al., 2013; Martínez-Toledo et al., 2021; Duggal et al., 2017) surpassing the water and soil limits allowed by the USEPA (15 μg L⁻¹ and 300 mg kg⁻¹, respectively). Plant growth and quality were affected due to the contamination of irrigation water and soil by HMs and Ms (Fernández-Macías et al., 2020).

The common bean, Phaseolus vulgaris L., belongs to the Fabaceae family (Hammami et al., 2022). This legume is the staple food of many countries, especially in Latin America and South-East Africa (Castro-Guerrero et al., 2016). It is the most produced and consumed food grain legume in the world and its market value exceeds that of all other legumes (FAOSTAT, 2021). This vegetable grows in temperate and subtropical regions and is an annual plant (Nwosu et al., 2018). In 2019, the common bean was planted in the world on 33, 066 183 ha with attainable yields of 874.0 kg ha⁻¹ (FAOSAT, 2021). This vegetable is known for its nutritional properties, including protein (22.06–32.63%), fiber (29.32–46.77%), resistant starch (9.16–18.09%), lipids (1.05–2.83%), and non-nutritional compounds such as trypsin inhibitors, lectins, saponins, phytic acid, tannins, and oligosaccharides which have chemopreventive, antiproliferative, antimutagenic, antioxidant and hypocholesterolemic properties (Corzo-Ríos et al., 2020). Some HMs are essential to plants at low concentrations, such as Zn, Mn, Fe, and Cu. However, other heavy metals such as As, Cd, Hg, and Pb are toxic to organisms. Pan et al. (2016) assessed the presence of As, Cd, Cr, Pb, Ni, and Hg in common beans in China. In countries such as Bangladesh and Brazil, Ahmed et al. (2016) and Ciminelli et al. (2017) detected arsenic in this legume with average concentrations of 0.31 ± 0.16 mg kg⁻¹ and 0.05 ± 0.05 mg kg⁻¹, respectively. The recommended values of As, Cd, Hg, and Pb in vegetables by the World Health Organization are 0.1, 0.02, 0.1, and 0.1–0.3 mg kg⁻¹, respectively (Kinuthia et al., 2020; Yuan et al., 2019).

Plants grown on heavy metal-contaminated soils result in a reduction of growth due to changes in their physiological and biochemical activities, which has been widely reported in the literature (Asati et al., 2016). Sadeghipour (2018) described the growth effects of Cd stress on common bean plants (reduction in shoot length, shoot dry weight, root dry weight, total dry weight, and leaf area). Hammami et al. (2022) reported adverse effects of HMs and Ms on common bean growth characteristics, including root and shoot dry weight, shoot-to-root ratio, and pod number. Bano et al. (2019) described the effects of As⁵⁺ on the growth of common bean plants, such as shoot height, root length, and leaf surface area reduction with increasing concentrations of this As species. Plants have evolved a complex system of enzymatic defense mechanisms against heavy metal-induced stress and nitrogen fixation. Enzymatic antioxidants include superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), and ascorbate peroxidase (APX) (Helal, 2019; Khalil et al., 2021).

Therefore, this review aims to summarize and understand the factors affecting the concentration of HMs and Ms on Phaseolus vulgaris L., and the effect of plants on HMs and Ms induced stress metabolism in field legume crops.