The presence of elements in the soil comes from natural components or anthropogenic sources. The main sources of anthropogenic soil pollution include transportation, mineral, organic fertilizers, pesticides, mining, metal smelting, urban solid and liquid waste, and transportation[17], [31]. The NAA method allows the determination of major and trace elements in the soil and able to taken up by plant roots. To ensure the validity of the results of the analysis using the NAA method, the quality assurance was carried out.
The quality assurance of the internal quality control in this study was carried out using SRM which can serve as a material for the internal quality control of a laboratory. The comparison ratio between the results of the SRM analysis obtained in this work and the values stated in the SRM certificate is presented in Fig. 2 for the soil matrix and Fig. 3 for the plant matrix. Overall, the ratio data for the four SRMs shows a ratio value of 0.9 < x > 1.1. It shows that the results of the analysis are not significantly different from the certificate value [32], [33].
Soil physiochemical properties
In this study, seasonal differences influence the soil physiochemical properties (Table 1). Soil pH ranged from 5.64 to 8.10 for the rainy season and 6.52 to 8.22 for the dry season. It indicates that the soil at the sampling location varies from a weak acid to a weak base. Soil temperatures ranged from 30.0 to 34.2 for the rainy season and 30.2 to 35.7 for the dry season. From the measurement results, it was known that there were differences of pH values in the dry season and the rainy season. For every sampling location, the pH of the rainy season was relatively lower than the dry season, as well as the temperature at every sampling site in the rainy season was lower than the dry season. Warm temperatures and high rainfall can cause the soil to tend to be more acidic. It was due to the presence of Ca, Mg, K cations in the soil undergoing a leaching process and leaving more stable elements such as Fe and Al oxides [34], [35].
Soil organic carbon was considered as an important factor to affect the soil quality, and directly affects the availability of macronutrients and micronutrients in the soil to be absorbed by plants [36]. Organic C content also correlate to the number of microorganisms and the stability of soil system [34]. In the dry season, organic C ranged from 0.31% − 0.83%, while the rainy season ranged from 0.51% − 0.99%. Organic C value at every sampling location in the dry season was relatively lower than the rainy season. It is related to the availability of water in the rainy season was higher than the dry season and the reduced intensity of sunlight causes microbial activity and intracellular enzyme activity in the soil become slow down. Thus, the microbiological decomposition process of organic waste slows down and the organic C content in the soil increases [37]. Additionally, temperature was thought to have an effect on the organic C content of the soil, where a higher temperature in the dry season causes the decomposition of organic matter to take place more quickly, thereby reducing organic carbon in the soil [38], [39].
Soil Redox Potential (Eh) describes the oxidation-reduction conditions in the soil expressed in volts [40]. The Eh value varies for each location, while the season differencies also influence to the Eh value. The Eh value of the rainy season ranged from 177 to 236 mV, while the Eh value of the dry season ranged from 179 to 238 mV. In the rainy season, the Eh value at every sampling location tends to be lower than the dry season. It is due to the increasing water content in the soil which reaches saturation in the rainy season and affects to the diffusion of oxygen in the water to be very slow, so that the soil Eh decreases. In addition, the growth of microorganisms in the rainy season tends to be faster due to environmental factors such as pH, temperature and soil moisture that encourage their growth so that the oxygen consumption in the soil increases and Eh decreases [41].
Table 1
The soil characteristic of 9 different sampling locations in the rainy and dry seasons
Locations | pH (H2O) | Temperature(°C) | %C | Eh (mV) |
wet | dry | wet | dry | wet | dry | wet | dry |
1 | 8.10 ± 0.02 | 8.12 ± 0.02 | 30.0 ± 0.01 | 30.2 ± 0.01 | 0.52 ± 0.15 | 0.34 ± 0.04 | 178 ± 3.02 | 179 ± 3.25 |
2 | 7.87 ± 0.01 | 8.22 ± 0.02 | 30.7 ± 0.02 | 30.9 ± 0.01 | 0.51 ± 0.2 | 0.31 ± 0.10 | 177 ± 4.42 | 180 ± 3.45 |
3 | 5.64 ± 0.03 | 6.52 ± 0.2 | 31.5 ± 0.01 | 31.6 ± 0.02 | 0.99 ± 0.10 | 0.82 ± 0.03 | 216 ± 3.10 | 220 ± 4.10 |
4 | 7.16 ± 0.02 | 7.37 ± 0.02 | 32.0 ± 0.01 | 32.5 ± 0.01 | 0.89 ± 0.10 | 0.67 ± 0.07 | 214 ± 5.65 | 216 ± 2.90 |
5 | 7.15 ± 0.02 | 7.49 ± 0.02 | 32.5 ± 0.02 | 34.1 ± 0.02 | 0.97 ± 0.15 | 0.78 ± 0.07 | 232 ± 3.64 | 236 ± 3.12 |
6 | 5.83 ± 0.02 | 6.59 ± 0.02 | 34.2 ± 0.01 | 35.7 ± 0.01 | 0.97 ± 0.14 | 0.67 ± 0.05 | 236 ± 3.94 | 238 ± 3.60 |
7 | 7.77 ± 0.02 | 8.14 ± 0.01 | 33.5 ± 0.01 | 34.8 ± 0.01 | 0.85 ± 0.19 | 0.83 ± 0.08 | 187 ± 2.45 | 190 ± 3.00 |
8 | 7.80 ± 0.02 | 7.84 ± 0.01 | 32.0 ± 0.01 | 32.2 ± 0.01 | 0.67 ± 0.10 | 0.41 ± 0.05 | 188 ± 2.56 | 190 ± 2.50 |
9 | 5.73 ± 0.02 | 6.66 ± 0.03 | 30.5 ± 0.01 | 31.3 ± 0.01 | 0.91 ± 0.12 | 0.80 ± 0.08 | 234 ± 3.04 | 236 ± 4.10 |
Soil analysis |
The result of elemental analysis in agricultural soil samples are presented in Table 2. They were varied at each location and different seasons. Based on the content percentage, it was known that soil samples from 9 sampling locations contain major elements (Al, Mn, Ti, Mg, Na, K and Fe), minor (V, Ba, Sr and Zn) and trace elements (U, Sm, Br, As, La, Se, Th, Cr, Hf, Sr, Sc, Rb and Co). The average concentrations of the Al, Mn, Ti, Mg, Na, K and Fe elements in the rainy season were 83681.14, 928.62, 4219.53, 12217.09, 5388.29, 11821.94, and 49504.76 mg.kg− 1, while in the dry season, 101790.31, 1157.11, 5013.41, 13846.47, 7167.24, 12766.66, and 58762.86 mg.kg− 1, respectively. The average concentrations of V, Ba, Sr, and Zn elements in the rainy season were 154.91, 284.97, 131.53, and 139.30 mg.kg− 1, while they were 177.67, 356.27, 175.05, and 158.47 mg. kg− 1 in the dry season. The average concentrations of U, Sm, Br, As, La, Se, Th, Cr, Hf, Sr, Sc, Rb and Co elements in the dry season were 3.44, 6.12, 2.45, 8.54, 26.77, 0.79, 10.75, 67.45, 4.30, 21.21, 56.80, and 24.36 mg.kg− 1, while they were 3.22, 5.37, 1.57, 7.75, 24.12, 0.40, 9.28, 57.42, 3.25, 18.87, 51.53, and 17.12 mg.kg− 1 in the rainy season. Nearly all elements in the soil in showed higher concentrations in dry than rainy seasons. This is probably due to the higher mobility and leaching of these elements and may also cause by the lower value of pH in rainy season as shown in Table 1. The evidence that lower pH value in wet season lead to the enhancement of mobility and therefore lower concentrations of metal elements was observed by Dinter, et al. (2021) [42] and Zhang, et. al. (2018)[43]. The abundance of those nine different elements in Table 2 should be contributed from anthropogenic sources such as fertilizer and pesticide and natural sounces such as soil weathering, pedogenic processes, and parent materials [44]
Table 2
Seasonal variation of element concentrations in soil samples taken from nine different sites (mg kg− 1 dry weight)
elements | Wet | Dry |
min | max | mean | SD | min | max | mean | SD |
U | 2.54 | 3.70 | 3.22 | 0.14 | 2.61 | 4.07 | 3.44 | 0.13 |
Ti | 3627.89 | 4990.06 | 4219.53 | 378.83 | 4376.77 | 5957.16 | 5013.41 | 379.79 |
Mg | 9676.62 | 13790.51 | 12217.09 | 561.88 | 12348.54 | 15300.80 | 13846.48 | 639.36 |
V | 142.48 | 194.75 | 154.91 | 10.60 | 152.57 | 200.82 | 177.67 | 11.60 |
Al | 65084.95 | 97497.87 | 83681.14 | 1223.83 | 68503.25 | 119656.05 | 101790.31 | 1341.46 |
Mn | 414.52 | 1125.98 | 928.62 | 97.54 | 914.57 | 1545.39 | 1157.11 | 103.22 |
Sm | 4.79 | 6.12 | 5.37 | 0.46 | 5.11 | 7.50 | 6.12 | 0.44 |
Br | 0.52 | 3.29 | 1.57 | 0.01 | 0.61 | 5.54 | 2.45 | 0.06 |
As | 6.70 | 9.79 | 7.75 | 0.84 | 5.21 | 10.27 | 8.54 | 0.83 |
Na | 4251.69 | 8287.96 | 5388.29 | 304.46 | 4525.75 | 10214.33 | 7167.24 | 321.77 |
K | 10646.77 | 13037.28 | 11821.94 | 213.11 | 10341.11 | 14275.36 | 12765.66 | 244.06 |
La | 18.60 | 28.23 | 24.12 | 2.53 | 24.33 | 32.04 | 26.77 | 1.67 |
Se | 0.26 | 0.70 | 0.40 | 0.13 | 0.41 | 1.21 | 0.79 | 0.19 |
Th | 6.68 | 12.46 | 9.28 | 0.12 | 8.53 | 12.72 | 10.75 | 0.56 |
Cr | 48.61 | 64.28 | 57.42 | 6.37 | 61.06 | 80.94 | 67.45 | 6.01 |
Ba | 165.26 | 399.23 | 284.97 | 54.65 | 231.08 | 501.62 | 356.27 | 66.39 |
Hf | 2.45 | 3.60 | 3.25 | 0.43 | 3.28 | 5.45 | 4.30 | 0.77 |
Sr | 85.46 | 232.65 | 131.54 | 14.35 | 97.47 | 265.39 | 175.05 | 9.18 |
Sc | 17.44 | 20.07 | 18.87 | 0.68 | 19.75 | 22.97 | 21.21 | 0.67 |
Rb | 36.78 | 65.75 | 51.53 | 5.08 | 43.24 | 68.29 | 56.80 | 5.15 |
Fe | 43658.75 | 58989.82 | 49504.76 | 325.76 | 51574.75 | 69673.22 | 58762.86 | 431.03 |
Zn | 121.42 | 147.97 | 139.30 | 25.44 | 127.19 | 205.92 | 158.47 | 18.18 |
Co | 13.43 | 22.14 | 17.12 | 2.96 | 19.69 | 31.66 | 24.36 | 2.25 |
Concentration of Trace Elements in Plant Tissues
Table 3 depicts the complete mean concentration of elements in plant samples obtained in dry and rainy seasons. Some elements have concentrations that are not significantly different between those in roots and leaves such as U, Ti, As, Th, Hf, Sr, Sc, Rb, Co and Al. The concentrations of Mn, Sm, La, Cr, Fe, and Zn elements in roots > leaves > bulbs, while the concentrations of Mg, K, Br, Na, Se, and Ba elements in leaves > roots > bulbs. These data are valid for all seasons. Most of the elements contained in the roots are larger than other parts of the plant, because the roots serve as the main medium for absorbing nutrients contained in the soil and they will be transferred to the leaves through the xylem to support the photosynthesis process [45] The concentrations of the Mg, K, Br, Na, Se, and Ba elements contained in the leaves were relatively higher than those in the roots, because these elements, especially Mg and K were needed in the process of photosynthesis that was occured in the leaves [46].
Sodium and Se are categorized as functional nutrient elements, where these elements are non-essential for plants but they are still needed in small amounts (similar to micronutrients) to help chlorophyll metabolism and synthesis. These elements can be used as a partial replacement for K and aid in the opening and closing of stomata, which helps regulate internal water balancing [47][48].
Bromine was an element that accumulate in plants easily, especially leaves in large quantities, but there is still no complete information on the function of Br in the environment [49]. Barium is a non-essential nelement that can cause several deleterious effects in most organisms. Increament of Ba concentration can be toxic to plants and affect growth and disrupt homeostasis. Barium can be accumulated in high amounts in roots and leaves [50].
The products of photosynthesis from the leaves will be circulated throughout the body to support the growth of plant and their residue will be stored in the bulbs as food reserves. This may cause the concentration of elements in the bulbs to be relatively much smaller than other parts of a shallot plant (roots as the main nutrient absorbing medium and leaves as the main medium for photosynthesis).
In Table 3 can also be seen that seasonal changes affect the elemental content in plants, where almost all elements in roots, except Ti, showed higher concentrations in dry season than wet season. Although the soil Ti content of the rainy season was lower than the dry season (Tabel 2), the uptake of Ti by plants in the rainy season was higher than the dry season (Table 3). It is caused by the presence of Ti of plants has a synergistic and antagonistic relationship with other nutrients, especially Fe. When plants experience Fe deficient, Ti helps induce the expression of genes associated with Fe acquisition, thereby increasing Fe uptake and utilization and further enhancing plant growth. Plants may have proteins that bind Ti specifically or non-specifically. When the concentration of Ti is high in plants, Ti will compete with Fe for ligands or proteins. Competition can be severe and causing the phytotoxicity of Ti. As a result, the beneficial effect of Ti becomes more pronounced when the plant experiences a shortage or lack of Fe supply [51].. It is relevant with this reseach where Ti and Fe consentrations of plants are inversely proportional (Table 3). In addition, Ti element was also needed by plants to improve plant performance by stimulating the activity of certain enzymes, increasing chlorophyll content and photosynthesis, increasing nutrient absorption, strengthening stress tolerance, and increasing crop yields and quality [51]. Titanium was also plays an active role in germination, root formation, and vegetative growth [52].
Table 3
Seasonal variation of mean concentration of elements in plant samples taken from nine different sites (mg kg− 1 dry weight)
elements | Wet | Dry |
root | bulbs | leaves | root | bulbs | leaves |
U | 0.03 ± 0.003 | 0.01 ± 0.001 | 0.02 ± 0.002 | 0.04 ± 0.003 | 0.01 ± 0.001 | 0.04 ± 0.003 |
Ti | 26.81 ± 2.63 | 7.21 ± 0.17 | 27.14 ± 2.83 | 22.20 ± 3.01 | 2.21 ± 0.16 | 22.90 ± 2.98 |
Mg | 5383.38 ± 224.35 | 1854.53 ± 115.83 | 7425.79 ± 301.23 | 6428.62 ± 242.02 | 1451.92 ± 118.06 | 6682.33 ± 231.10 |
V | 8.28 ± 0.62 | 0.95 ± 0.08 | 8.76 ± 0.67 | 10.19 ± 0.92 | 0.74 ± 0.07 | 7.65 ± 0.62 |
Al | 4403.42 ± 231.85 | 339.75 ± 24.74 | 4015.25 ± 210.38 | 4875.13 ± 230.44 | 235.93 ± 20.01 | 3647.47 ± 212.09 |
Mn | 147.64 ± 10.48 | 41.74 ± 2.14 | 113.49 ± 9.23 | 152.51 ± 10.92 | 45.57 ± 2.21 | 118.04 ± 9.01 |
Sm | 0.32 ± 0.03 | 0.04 ± 0.004 | 0.23 ± 0.02 | 0.46 ± 0.04 | 0.04 ± 0.003 | 0.29 ± 0.003 |
Br | 35.59 ± 3.00 | 16.09 ± 1.46 | 72.20 ± 5.82 | 63.75 ± 5.01 | 21.28 ± 1.90 | 127.83 ± 8.90 |
As | 0.50 ± 0.05 | 0.24 ± 0.02 | 0.47 ± 0.05 | 0.53 ± 0.05 | 0.05 ± 0.03 | 0.78 ± 0.06 |
Na | 6563.64 ± 302.54 | 2313.41 ± 110.92 | 12040.79 ± 498.40 | 15943.73 ± 504.75 | 2328.72 ± 108.84 | 27179.52 ± 700.80 |
K | 11743.66 ± 583.03 | 9470.38 ± 402.45 | 12337.03 ± 601.03 | 12676.20 ± 634.94 | 13833.71 ± 697.06 | 13539.66 ± 598.93 |
La | 2.28 ± 0.19 | 0.47 ± 0.04 | 1.57 ± 0.12 | 2.50 ± 0.19 | 0.30 ± 0.03 | 1.08 ± 0.10 |
Se | 0.04 ± 0.005 | 0.02 ± 0.002 | 0.09 ± 0.01 | 0.04 ± 0.005 | 0.01 ± 0.002 | 0.11 ± 0.01 |
Th | 0.32 ± 0.02 | 0.03 ± 0.003 | 0.28 ± 0.02 | 0.51 ± 0.03 | 0.02 ± 0.001 | 0.35 ± 0.02 |
Cr | 8.53 ± 0.45 | 3.25 ± 0.18 | 5.49 ± 0.26 | 9.76 ± 0.50 | 4.233 ± 0.20 | 6.98 ± 0.31 |
Ba | 11.84 ± 0.98 | 2.11 ± 0.22 | 29.31 ± 1.79 | 16.12 ± 1.48 | 1.71 ± 0.48 | 32.98 ± 2.87 |
Hf | 0.18 ± 0.01 | 0.02 ± 0.002 | 0.18 ± 0.01 | 0.26 ± 0.02 | 0.01 ± 0.002 | 0.19 ± 0.02 |
Sr | 118.49 ± 12.83 | 27.13 ± 2.74 | 97.05 ± 10.37 | 144.95 ± 45.49 | 26.44 ± 4.02 | 119.78 ± 12.03 |
Sc | 1.17 ± 0.1 | 0.04 ± 0.002 | 0.92 ± 0.08 | 1.57 ± 0.10 | 0.02 ± 0.002 | 1.14 ± 0.1 |
Rb | 2.56 ± 0.12 | 0.66 ± 0.03 | 2.93 ± 0.14 | 3.18 ± 0.16 | 0.74 ± 0.04 | 3.95 ± 0.16 |
Fe | 3559.680 ± 127.66 | 144.16 ± 9.79 | 2806.35 ± 107.03 | 4292.14 ± 130.59 | 104.45 ± 9.98 | 3197.23 ± 112.85 |
Zn | 123.68 ± 10.93 | 26.92 ± 2.00 | 34.81 ± 3.08 | 152.94 ± 11.04 | 31.33 ± 2.25 | 109.39 ± 8.99 |
Co | 1.44 ± 0.07 | 0.30 ± 0.01 | 1.50 ± 0.07 | 1.76 ± 0.07 | 0.22 ± 0.01 | 1.26 ± 0.06 |
The concentrations of U, Mn, Sm, Br, As, Na, K, Se, Th, Cr, Ba, Hf, Sr, Sc, Rb, Fe, Zn and Co elements in the leaves of shallot plants in the dry season are relatively higher than those in the rainy season, while the Ti, Mg, V, Al and La elements vice versa The concentrations of Ti, Mg, V, Al, Sm, As, Na, La, Se, Th, Ba, Hf, Sr, Sc, Fe, and Co elements in shallot bulbs in the rainy season are relatively higher than those in the dry season, while for U, Mn, Br, K, Cr, Rb, and Zn elements, their concentrations in dry season are relatively higher than those in the rainy season. It may relate to the rate of photosynthesis of plants, where the rate of photosynthesis in the rainy season tends to be lower than the dry season [53], [54]. This causes the content of elements of the leaves in the dry season to be relatively higher, while the water content of the leaf mesophyll tissue is higher [55]. This causes the elements to have higher mobility to move towards the bulbs as a storage medium for photosynthetic food reserves so that the content of elements of the bulbs in the rainy season were relatively higher than the dry season.
Bioconcentration and translocation in the soil shallot system
In this study, the bio-concentration factor coefficient (BFC) is used to determine the level of absorption of elements in the soil by shallot plants. Figure 4(a). shows the BFC values of the elements in the shallot plant. In the rainy season, it is seen that the mean BFC value from the largest to the lowest is Br > Na > K > Sr > Zn > Mg > Mn > Cr > Se > La > Co > Fe > As > Sc > Sm > Hf > V > Al > Rb > Ba > Th > U > Ti, while the mean BFC value in the dry season is in the sequence Br > Na > K > Zn > Sr > Mg > Cr > Mn > Co > La > Sm > Sc > Fe > As > Hf > Se > V > Rb > Al > Th > Ba > U > Ti. The mean BFC value of Br is significantly different from other elements (> 20). It shows that the roots can absorb Br effectively from the soil to the leaves and then to the shallot bulbs as also observed by Galinha, et. al. (2010) [56], while the smallest BFC mean value is Ti (< 0.007) indicating roots are not easy to absorb Ti from the soil. The greater BCF value the more easily an element to be absorbed from soil and the smaller the BCF value the more difficult an element to be translocated from the soil by plants [17][57].
In the dry season, the mean BFC value for nearly all elements are relatively higher than the rainy season, except for the Al, Mn, Se, Cr, La, As, and Sr. Many factors play significant role for the BCF value, including soil and plant physiochemical properties [58].
Figure 4(b) and (c) depict that the translocation of elements from the roots to the leaves were greater than from the roots to the bulbs of shallots, because all the elements absorbed by the roots will be transferred to the leaves to support the photosynthesis process. The mean TF values of elements from the roots to the leaves are in the order Se > Ba > Br > Na > As > Mg > Rb > K > Ti > V > Hf > Al > Sr > U > Th > Mn > Fe > Sc > Co > Cr > Sm > La > Zn, Meanwhile the mean TF values of the elements from the roots to the shallot bulbs are in the order K > Cr > Br > Se > Mn > As > Mg > Na > Rb > U > Zn > Ti > La > Sr > Co > Ba > Sm > V > Hf > Al > Th > Fe > Sc. Bioconcentration factor of K (0.993) was not so different from TF value from the roots to the leaves (1.05) and TF value from the roots to the shallot bulbs (0.806). Potassium is the most abundant inorganic cation and plays an important role in optimizing plant growth. Additionally, K is also an activator of dozens of important enzymes, such as protein synthesis, sugar transport, N and C metabolism, and photosynthesis so that K has strong mobility in plants to regulate cell osmotic pressure and balance cations and anions in the cytoplasm [59]. This is why BCH and TF of K evenly distributed throughout the plant body. Some elements that have a high abundance in the soil such as Fe and Al are not optimally absorbed by plants. Absorption of Fe and Al from the soil by roots were relatively small (BFC) < 0.1. Iron and Al are trace elements whose presence in small amounts is essential for plants for metabolism and growth, while in excess amount will be toxic to these plants [60], [61]. The transfer factor of Fe and Al from roots to leaves (TF of Fe = 0.767 and Al = 0.830) are greater than that to shallot bulbs (TF of Fe = 0.032 and Al = 0.063). This explains that although the absorption of Fe and Al are very small by the roots, these elements are able to be optimally translocated to the leaves and slightly to the bulbs.
Environmental conditions greatly affect the transfer of elements from the soil to the growing body. It can be seen in Fig. 4 where seasonal differences affect the translocation of elements in plants. In Fig. 4(b) and (c). it is seen that the translocation of Ti, Mg, V, Al, Sm, Br, Na, La, Th, Ba, Hf, Sc, Fe, and Co elements from the roots to the leaves and the shallot bulbs in the rainy season are relatively higher than the dry season. The translocation factor of Cr, U, Mn, and Sr elements from the roots to the leaves and the shallot bulbs in the rainy season are smaller than the dry season. The translocation factor of As, Se, and Zn elements from roots to the leaves in the rainy season are smaller than the dry season, but the translocation of these elements from roots to the shallot bulbs in the rainy season are greater than the dry season. The elements of As, Se and Zn are heavy metals are deeded by plants to synthesize chlorophyll-forming enzymes as a proponent of the photosynthesis process [62]–[64]. As temperature increases 0.5–1°C due to seasonal changes, the content of chlorophyl in leaves decreases [65], so plants will try to balance chlorophyll needs by absorbing more elements needed to increase chlorophyll-forming enzymes in the leaves.
Risk identification and human health risk assessment
Food safety is related to the assessment of foodstuffs that grow on the polluted soils associated with human health risks in consuming these foodstuffs [12]. Human health risk assessment is an effort to estimate the intake of heavy metals from consumed food and it can be accumulated in the human body in order to minimize health risks. In this study, the identification of health risks due to consumption of shallot is assessed based on the intake of elements contained in the bulbs of shallots and the results are presented in Table 4. There are not more literature that discusses the content of heavy metals and trace elements in shallot which are toxic to humans. In this study, health risk assessment refers to the content of heavy metals and trace elements which are toxic in onions (such as U, V, Al, Mn, As, Cr, Fe, Zn, Co, Th, Ba and Sr) [20], [66]–[68] considering that onions and shallots are the same family. The identification of health risks on roots and leaves are not carried out because in general, the roots and leaves of shallot are not consumed.
The concentration of heavy metals (dry weight) in plants was converted to a fresh weight basis using their water content to obtain a ratio equivalent to FAO/WHO food standards [20][69]. All calculated THQ values for rainy and dry seasons were < 1. It indicates that the health risks associated with exposure to every element listed in Table 4due to the consumption of shallots grown in the rainy and dry seasons, do not have a significant impact on health for both men and women. The health hazard index (HI) of the toxic elements due to consumption of shallots (both planted in the rainy and dry seasons) is also lower than 1 for men and women. This shows that there is no significant potential health risk for men or women who consume shallots, both planted in the rainy and dry seasons.
Table 4
Estimated daily intake by males and females and potential health risk due to consumption of bulbs of shallots planted in the rainy and dry seasons
Gender | element | RfD1 | Wet | Dry |
EDI2 | THQ3 | HI4 | EDI2 | THQ3 | HI4 |
Males | U | 3b | 0.001 | 0.0003 | 0.146 | 0.001 | 0.0004 | 0.127 |
V | 5c | 0.117 | 0.024 | 0.091 | 0.018 |
Al | 1000d | 41.745 | 0.042 | 28.989 | 0.029 |
Mn | 140e | 5.129 | 0.037 | 5.600 | 0.040 |
As | 50a | 0.030 | 0.0006 | 0.006 | 0.0001 |
Cr | 1500f | 0.399 | 0.0003 | 0.520 | 0.0003 |
Fe | 700e | 17.713 | 0.025 | 12.834 | 0.018 |
Zn | 300a | 3.308 | 0.011 | 3.850 | 0.019 |
Co | 43e | 0.037 | 0.001 | 0.027 | 0.0006 |
Th | 3b | 0.003 | 0.001 | 0.003 | 0.001 |
Ba | 200c | 0.259 | 0.001 | 0.221 | 0.001 |
Sr | 600c | 2.105 | 0.004 | 3.248 | 0.005 |
Females | U | 3b | 0.001 | 0.0003 | 0.156 | 0.001 | 0.0004 | 0.136 |
V | 5c | 0.125 | 0.025 | 0.097 | 0.019 |
Al | 1000d | 44.624 | 0.045 | 30.989 | 0.031 |
Mn | 140e | 5.483 | 0.039 | 5.986 | 0.043 |
As | 50a | 0.032 | 0.0006 | 0.006 | 0.0001 |
Cr | 1500f | 0.427 | 0.0003 | 0.556 | 0.0004 |
Fe | 700e | 18.935 | 0.027 | 13.720 | 0.020 |
Zn | 300a | 3.536 | 0.012 | 4.116 | 0.014 |
Co | 43e | 0.040 | 0.001 | 0.029 | 0.0007 |
Th | 3b | 0.003 | 0.001 | 0.003 | 0.001 |
Ba | 200c | 0.277 | 0.001 | 0.225 | 0.001 |
Sr | 600c | 2.250 | 0.004 | 3.473 | 0.006 |
1 Reference oral dose (µg kg− 1 day− 1).
2 Estimated daily intake (µg kg− 1 day− 1).
3 Target Hazard Quotient (EDI/RfD).
4 Hazard Index when multiple metals are present (ƩTHQn; n = 1 to i)
a [20]; b [71]; c [72]; d [70]; e [73]; f [74]