Abstract
This study aimed to determine the concentrations of heavy metals and assess the health risk associated with their exposure through the consumption of Edible Leafy Vegetables (ELVs) distributed in Rafsanjan, the southeast area of Iran. In this study, samples of commonly consumed ELVs, including Coriander, Parsley, Persian Leek, Radish, Basil, and Lettuce, were collected over four seasons in 2024. Inductively coupled plasma mass spectrometry (ICP-MS) was used to quantify the concentration of heavy metals lead (Pb), mercury (Hg), arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), copper (Cu), aluminum (Al), iron (Fe), manganese (Mn), and zinc (Zn). The concentration of toxic heavy metals was observed for As in Leek during the summer (16.33 ± 1.21 mg/kg), Cr in Lettuce during the winter (13.21 ± 1.16 mg/kg), and Pb in Radish during the summer (6.10 ± 1.33 mg/kg). The overall order of toxic heavy metal concentrations in the samples was As ˃ Cr ˃ Pb ˃ Ni ˃ Cd, and the most contaminated ELVs were ranked Leek ˃ Lettuce ˃ Radish ˃ Parsley ˃ Basil ˃ Coriander. The highest hazard quotient (HQ) value was recorded for As in Leek (4.8733 in children, 4.6993 in adults), AS Lettuce (1.3689 in children, 1.2571 in adults), and Cr in Lettuce (1.6139 in children, 1.4821 in adults). The highest hazard index (HI) values were observed for Leek, followed by Lettuce and Basil. In addition, the highest carcinogenic risk (CR) values were associated with Cr in Lettuce, As in Leek, and Cr in Basil, respectively. Therefore, continuous monitoring of heavy metals, particularly As and Cr in ELVs, is recommended to identify and mitigate contamination sources.
Keywords: Heavy metals, Vegetables, Edible plant, Risk assessment, Environmental exposure
Subject terms: Environmental sciences, Risk factors
Introduction
Edible Leafy Vegetables (ELVs) are among the most important components of a healthy and balanced human diet, as they contain a wide range of vitamins, minerals, fiber, and other nutrients1,2. Numerous studies in recent years have shown that the daily consumption of vegetables can help prevent cardiovascular diseases and certain type of cancers, particularly gastrointestinal cancer3,4. Trace elements such as Iron (Fe), Magnesium (Mg), Zinc (Zn), and Manganese (Mn) are naturally present in vegetables and are essential for human health at low concentrations; however, when accumulated at elevated levels, they may exert adverse effects on the body5.
Recently, concerns have been intensified regarding the potential contamination of ELVs with toxic heavy metals6,7. Vegetables can become contaminated through various pathways, including irrigation with industrial wastewater or contaminated water sources, the application of pesticides or agricultural fertilizers, and the release of industrial pollutants during the growth, harvesting, storage, and sale of vegetables8–10. Furthermore, sewage sludge, often utilized by farmers as a cost-effective fertilizer due to its rich nutrient content, can introduce these nutrients, and potentially associated contaminants, into plants, particularly ELVs, through absorption11,12. The contamination of food and agricultural products with heavy metals and toxins presents a significant challenge to food safety and hygiene worldwide13,14. Heavy metals such as As, Hg, Pb, Cd, and Cr, along with other toxins, can readily enter plants and ELVs via water, soil, and air (through stomatal uptake)15,16. Plant roots are capable of absorbing heavy metals, which are then gradually translocated to the edible portions. Due to their inherent stability, these metals can accumulate in various plant parts, especially the leaves of ELVs. Consequently, they easily enter the human’s food chain upon consumption of these contaminated food products17,18.
The primary routes of human exposure to heavy metals include ingestion (via the digestive system), inhalation (via the respiratory system), and dermal contact (via the skin)19. However, ingestion through accompanied food or drinking water remains the predominant pathway for heavy metals interring20,21. Food contamination, particularly in ELVs which are consumed daily, is therefore a significant public health concern. Following absorption from the digestive system, heavy metals enter the bloodstream and can disseminate to numerous vital tissues and organs, leading to serious health complications in humans and other organisms22,23. Many heavy metals, including As, Cd, Pb, and Hg, are toxic even at very low doses and process the characteristic of gradual accumulate within the tissues of living organisms24. This accumulation can lead to distortion in lipid metabolism and the development of fatty liver diseases through deposition in adipose tissues25,26. Exposure to heavy metals has been linked to adverse effects on the central nervous system, endocrine system, immune system, cardiovascular system, and cellular metabolism, potentially causing wide range of acute and chronic diseases27,28. Furthermore, chronic exposure can disturb ionic balance and mineral regulation, induce oxidative damage to cellular structures, cause DNA damage28, lead to reproductive toxicity27, exhibit carcinogenic effects such as liver, kidney, and bladder cancers29, and result in mutagenic effects30. Intake of heavy metals exceeding permissible limits can result in non-carcinogenic risks, including liver and kidney diseases, hypertension, diabetes, anemia, and neurological and psychiatric disorders11,31.
ELVs are particularly prone to accumulating high Level of heavy metals owing to their enhanced retention and absorption capacities, and the tendency for these metals to concentrate in their leaves32. Research conducted globally, including studies within Iran, has consistently reported heavy metal contamination in a variety of vegetables33–35. Consequently, assessing the health risk associated with heavy metals exposure through ELVs consumption is a crucial initial step towards improving food safety and public health worldwide36. Health risk assessment (HRA) is a stablished methodology for estimating and of quantifying the potential health risk posed by various pollutants. This process considers factors such as the duration and Level of exposure, alongside pollutant concentration19. As an integral component of health and safety management, risk assessment serves to identify, evaluate, and control hazardous pollutant37. Therefore, conductive comprehensive HRA studies for ELVs across different geogeraphical region is essential. Such studies can quantitatively estimate the carcinogenic and non-carcinogenic risks associated with exposure to hazardous heavy metals, thereby informing strategies to mitigate adverse effects. Ultimately, this approach can significantly reduce exposure to heavy metals and their associated harms, while concurrently enhancing food safety and hygiene standards globally38,39.
Rafsanjan, situated in the northern part of Kerman province and southeastern region of Iran, is a city characterize by significant agriculture, industry, and mining. Previous research indicates the presence of heavy metals in the water resources of this city, and Kerman province generally, at varying concentrations across numerous areas. Consequently, these metals have the potential to enter the food chain40. Given the importance of monitoring and investigating the presence of heavy metals in raw ELVs - an essential component of the human diet - and assessing the health risk, this study was undertaken. Furthermore, considering that no prior research has addressed this specific issue in Rafsanjan city, the present study aimed to determine and evaluate the health risk stemming from exposure to heavy metals through the consumption of raw ELVs available in Rafsanjan city during 2024.
Materials and methods
Study area and sampling
This descriptive-analytical, cross-sectional study was conducted to quantify heavy metal concentration in ELVs available in Rafsanjan city during 2024 and to assess the associated health risk from their consumption. Rafsanjan city is geographically located in the north of Kerman province, within the coordinates of 55°0’ to 46°53’50” East and 30°5’ to 31°5’ North, representing the southeast of Iran. The study involved the random collection of samples from six commonly consumed type of ELVs: including Persian Leek, Coriander, Parsley, Basil, Radish, and Lettuce. Sampling was performed across 10 raw vegetable distribution centers within Rafsanjan city, representing diverse geographical areas. To account for seasonal variation, sampling occurred randomly over four seasons in 2024, with one month designated per season and three replicate samples collected each month. Subsequently, samples of the some ELVs type from different distribution units (assuming common distribution centers and source) were pooled. Reached pooled samples was then divided into six subsamples, corresponding to the six ELVs types. With three pooled samples per month for each vegetable type, a total of 18 samples were analyzes per month.
Across the four seasons, this resulted in a final sample size of 72 analyzed samples.
Sampling preparation and experimental setup
Upon collection, samples were transported to the laboratory and initially washed with tab water to remove superficial dirt and sediment. Following this, a thorough rinse with distilled water was performed. subsequently,100 gr aliquots of each sample were precisely weighed. The samples were then dried in a forced-air oven at 70 °C until a constant weight was achieved, ensuring complete moisture removal. For subsequent ashing, he dried sample were finely ground and passed through a 2 mm sieve. The ground material was then subjected to incineration in an electric muffle furnace at 500 °C for 4 h, converting the vegetable matter into ash41. For the acid digestion of vegetables, 10 ml of 95% nitric acid was added to each gram of ash. The mixture was incubated in a water bath at 70–80 ˚C for 6 h to facilitate the digestion of organic matter. Following this initial digestion 10 ml of hydrochloric acid (6 Molar) was added, and the mixture was re-incubated under the same temperature. Finally, after adding 10 ml of distillated water, the liquid was passed through Whatman filter paper No. 42. The filtrate was then diluted to a final volume of 50 ml in a volumetric flask in preparation for heavy metal analysis37.
Heavy metals analysis
A prepared digest was subsequently analyzed using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) (Agilent Series Hp 4500, USA). The concentration of the following heavy metals were quantified: As, Hg, Pb, Cd, Cr, Ni, Cu, Fe, Al, Mn, and Zn. The instruments’ limit of detection (LOD) were established as follow:
Within 0.01 mg/kg for As, Hg, Pb, and Cd.
Within 0.1 mg/kg for Cr, Ni, Cu, Mn, and Zn.
Up to 10 mg/kg for Fe and Al.
Validate recovery rates for the heavy metal, assessed through quality control measures, ranged from:
95 to 108% for As.
96 to 101% for Pb.
93 to 104% for Cd.
96 to 102% for Cr.
89 to 105% for Ni.
90 to 105% for Cu.
92 to 102% for Mn.
88 to 106% for Zn.
95 to 104% for Fe.
99 to 108% for Al.
Health risk assessment
Average daily dose determination
The equation used to calculate the average daily dose (ADD) is as follows:
 |
ADD represents the daily intake dose in µg/g.day.
C is the average heavy metal concentration in vegetables in mg/kg.
IR (Ingestion rate) is the daily per capita consumption of vegetables in g/day. Based on Iranian dietary pattern in this study, the IR values are:
Coriander, parsley, and Leek: 2 g/day for children and 9 g/day for adults.
Radish: 1 g/day for children and 3 g/day for adults.
Basil: 4 g/day for children and 12 g/day for adults.
Lettuce: 7 g/day for children and 30 g/day for adults42.
EF (Exposure frequency) is considered to be 365 days per year for both groups of children and adults.
ED (Exposure duration) is considered to be 6 years for children and 30 years for adults.
CF (Conversion factor) is the unit conversion factor, which is 0.00137,43.
BW (Body weight), body weight in kg, which is 15 kg for children and 70 kg for adults40.
AT (Average time) or average exposure time in days, which is calculated from the product of EF and ED, which in this study is 2190 days for non-carcinogenic risk for children and 10,950 days for adults. In the lifetime carcinogenic risk, ED values are 70 years in both age groups, and as a result, AT values are also considered to be 25,550 days for both age groups43.
Non-carcinogenic health risk assessment
To determine the non-carcinogenic risk for each metal, the hazard quotient index (HQ) was calculated using the following equation:
 |
Where:
HQ is the hazard coefficient (dimensionless) for each metal. ADD is the daily intake dose in µg/g.d. RfD is the reference dose for each metal in µg/g.d, which in this study are 0.0003, 0.001, 0.003, 0.02, 0.0036, 0.04, 1, 0.7, 0.046, and 0.3 for As, Cd, Cr, Ni, Pb, Cu, Al, Fe, Mn, and Zn, respectively37. The Hazard index (HI), representing the total non-carcinogenic risk for all heavy metals, was calculated by using the following equation14.
 |
Carcinogenic health risk assessment
The following equation was used to determine the amount of cancer risk for each heavy metal:
 |
Where:
CR represent the carcinogenic risk (dimensionless); Add is the average daily intake dose in terms of µg/g.d; CSF (Cancer Slope Factor) is a carcinogenic slope (mg/kg.d). which CSF in study is 1.5, 0.38, 0.5, 1.7, and 0.0085, respectively, for As, Cd, Cr, Ni, and Pb. The amount of total Incremental Lifetime Carcinogenic Risk (ILCR), is calculated based on the following equation from the sum of the carcinogenic risk of each metal or CR44.
 |
Statistical analysis
For determining differences in heavy metal concentrations across different seasons and different ELVs, an ANOVA test was used at significant Levels of < 0.05.
Results and discussion
Metals levels in edible ELVs in different seasons
In Table 1, the average Heavy metal concentration, including As, Cd, Cr, Ni, Pb, and Hg are presented in a variety of vegetable species distributed in Rafsanjan, including Coriander, Parsley, Persian Leek, Radish, Basil, and Lettuce across different seasons of 2024. Hg concentration in all ELVs in all samples was not detectable. The maximum toxic heavy metal concentration in Coriander vegetable species was related to Cr (3.85 ± 0.39 mg/kg) in summer, Ni (1.65 ± 0.83 mg/kg) in winter, Pb (1.33 ± 0.53 mg/kg) in summer, and As (1.10 ± 0.18 mg/kg) in winter. The maximum heavy metal concentration in parsley was related to Cr (7.65 ± 1.92 mg/kg) in summer, Ni (1.96 ± 0.89 mg/kg) and as (1.20 ± 0.45 mg/kg) in winter, and Pb (1.18 ± 0.25 mg/kg) in summer.
Table 1.
Toxic heavy metal concentration of six edible leafy vegetables in different seasons.
| Vegetables | Seasons | Metal concentration (mg/kg) (Mean ± SD) | |||||
|---|---|---|---|---|---|---|---|
| As | Cd | Cr | Ni | Pb | Hg | ||
| Coriander | Spring | 0.64 ± 0.10 | ˂ 0.01 | 3.11 ± 0.78 | 1.01 ± 0.34 | 1.15 ± 0.38 | ND* |
| Summer | 0.58 ± 0.10 | ˂ 0.01 | 3.85 ± 0.39 | 1.18 ± 0.46 | 1.33 ± 0.53 | ||
| Autumn | 0.89 ± 0.11 | 0.10 ± 0.09 | 3.42 ± 0.41 | 1.25 ± 0.55 | 1.18 ± 0.22 | ||
| Winter | 1.10 ± 0.18 | 0.11 ± 0.08 | 3.11 ± 0.25 | 1.65 ± 0.83 | 0.97 ± 0.45 | ||
| Parsley | Spring | 0.52 ± 0.19 | 0.13 ± 0.09 | 7.12 ± 1.53 | 1.42 ± 0.55 | 0.88 ± 0.13 | |
| Summer | 0.55 ± 0.31 | 0.11 ± 0.08 | 7.65 ± 1.92 | 1.20 ± 0.31 | 1.18 ± 0.25 | ||
| Autumn | 0.85 ± 0.33 | 0.17 ± 0.08 | 6.41 ± 1.28 | 1.55 ± 0.65 | 0.98 ± 0.12 | ||
| Winter | 1.20 ± 0.45 | 0.20 ± 0.08 | 6.15 ± 1.35 | 1.96 ± 0.89 | 0.83 ± 0.23 | ||
| Persian Leek | Spring | 14.90 ± 1.89 | 0.23 ± 0.1 | 5.64 ± 1.42 | 0.98 ± 0.13 | 2.43 ± 0.76 | |
| Summer | 16.33 ± 1.21 | 0.21 ± 0.10 | 5.10 ± 1.15 | 0.92 ± 0.11 | 2.10 ± 0.55 | ||
| Autumn | 8.15 ± 1.11 | 0.29 ± 0.10 | 6.42 ± 1.25 | 0.99 ± 0.11 | 2.95 ± 0.85 | ||
| Winter | 4.45 ± 0.92 | 0.30 ± 0.1 | 7.12 ± 1.2 | 1.10 ± 0.14 | 3.11 ± 0.94 | ||
| Radish | Spring | 0.48 ± 0.11 | 0.11 ± 0.08 | 5.31 ± 1.52 | 0.95 ± 0.21 | 5.92 ± 1.56 | |
| Summer | 0.34 ± 0.13 | 0.12 ± 0.07 | 5.10 ± 1.23 | 1.10 ± 0.17 | 6.10 ± 1.33 | ||
| Autumn | 1.10 ± 0.21 | 0.12 ± 0.09 | 5.25 ± 1.34 | 0.93 ± 0.11 | 2.54 ± 0.93 | ||
| Winter | 1.33 ± 0.25 | 0.11 ± 0.09 | 6.11 ± 1.22 | 0.91 ± 0.18 | 2.33 ± 0.88 | ||
| Basil | Spring | 0.44 ± 0.12 | 0.15 ± 0.10 | 3.96 ± 0.89 | 0.87 ± 0.13 | 0.89 ± 0.2 | |
| Summer | 0.54 ± 0.19 | 0.12 ± 0.11 | 3.41 ± 0.81 | 0.99 ± 0.10 | 0.95 ± 0.17 | ||
| Autumn | 0.50 ± 0.18 | 0.17 ± 0.1 | 5.82 ± 1.33 | 0.84 ± 0.10 | 0.88 ± 0.22 | ||
| Winter | 0.41 ± 0.20 | 0.19 ± 0.11 | 7.45 ± 1.34 | 0.75 ± 0.10 | 0.75 ± 0.10 | ||
| Lettuce | Spring | 0.95 ± 0.24 | 0.14 ± 0.11 | 8.86 ± 1.38 | 0.85 ± 0.27 | 1.01 ± 0.22 | |
| Summer | 1.21 ± 0.23 | 0.11 ± 0.10 | 8.11 ± 1.24 | 1.01 ± 0.31 | 1.31 ± 0.21 | ||
| Autumn | 0.66 ± 0.28 | 0.17 ± 0.10 | 11.32 ± 1.41 | 0.78 ± 0.21 | 1.12 ± 0.25 | ||
| Winter | 0.70 ± 0.21 | 0.21 ± 0.12 | 13.21 ± 1.16 | 0.65 ± 0.23 | 0.96 ± 0.29 | ||
| WHO/FAO | 0.1 | 0.02 | 5 | - | 0.3 | ||
*ND: not detectable.
The maximum heavy metal concentration in Leek was related to As (16.33 ± 1.21 mg/kg) (the highest value in total vegetables), in summer, Cr (7.12 ± 1.20 mg/kg), and Pb (3.11 ± 0.94 mg/kg) in winter. The maximum heavy metal concentration in Radish was related to Cr (6.11 ± 1.22 mg/kg), and As (1.33 ± 0.25 mg/kg) in winter, and Pb (6.10 ± 1.33 mg/kg) in summer. The maximum heavy metal concentration in Basil was related to Cr in winter (7.45 ± 1.34 mg/kg), Ni (0.99 ± 0.10 mg/kg), Pb (0.95 ± 0.17 mg/kg), and As (0.54 ± 0.19 mg/kg) in summer. The maximum heavy metal concentration (Pb, Hg, As, Cd, Cr, and Ni) in the lettuce species was related to Cr in winter (13.21 ± 1.16 mg/kg), Pb (1.31 ± 0.21 mg/kg), and As (1.21 ± 0.23 mg/kg). The results of the toxic heavy metal concentration in different seasons (Table 1) show that in the vegetable species, the average concentration of As, Cr, and Pb in four seasons and Cd in the fall and winter seasons are higher than the Food and Agriculture Organization (FAO) and World Health Organization (WHO) standard values45. In Parsley, Leek, Radish, and Lettuce, the average As, Cd, Cr, and Pb, and in Basil, the average As, Cd, and Pb in all seasons and Cr in autumn and winter, are higher than the standard FAO and WHO values45.
In Table 2, the average concentration of other surveyed heavy metals, which includes Al, Cu, Mn, and Zn, is presented for a variety of ELVs distributed species in Rafsanjan, including Coriander, Parsley, Persian Leek, Radish, Basil, and Lettuce in different seasons of 2024. According to the results, the maximum concentration of other heavy metals in all ELVs was related to the two metals Fe and Al, respectively. In summer, their concentration was highest in Coriander for Fe (838.21 ± 35.79 mg/kg) and Al (358.15 ± 28.99 mg/kg), in Parsley for Fe (455.11 ± 24.78 mg/kg) and Al (404.22 ± 21.94 mg/kg), in Leeks for Fe (772.45 ± 33.82 mg/kg) and Al (586.11 ± 29.68 mg/kg), in Radish for Fe (568.33 ± 24.51 mg/kg) and Al (452.31 ± 16.45 mg/kg), in Basil for Fe (604.81 ± 33.99 mg/kg) and Al (459.24 ± 24.36 mg/kg), and in Lettuce for Fe (452.20 ± 20.44 mg/kg) and Al (440.62 ± 18.35 mg/kg).
Table 2.
Other heavy metal concentration of six edible leafy vegetables in different seasons.
| Vegetables | Seasons | Metal concentration (mg/kg) (Mean ± SD) | ||||
|---|---|---|---|---|---|---|
| Cu | Al | Fe | Mn | Zn | ||
| Coriander | Spring | 14.63 ± 1.22 | 335.33 ± 25.44 | 810.85 ± 31.54 | 12.34 ± 1.31 | 22.48 ± 2.63 |
| Summer | 13.15 ± 1.42 | 358.15 ± 28.99 | 838.21 ± 35.79 | 10.88 ± 1.42 | 19.31 ± 2.26 | |
| Autumn | 14.76 ± 1.54 | 350.5 ± 29.87 | 781.30 ± 39.68 | 13.21 ± 1.28 | 25.64 ± 2.89 | |
| Winter | 16.54 ± 1.78 | 330.22 ± 26.88 | 755.60 ± 38.90 | 15.65 ± 1.43 | 32.15 ± 2.54 | |
| Parsley | Spring | 17.85 ± 2.63 | 388.23 ± 28.58 | 415.35 ± 30.49 | 19.24 ± 2.59 | 18.35 ± 2.47 |
| Summer | 18.91 ± 2.31 | 402.22 ± 21.94 | 455.11 ± 24.78 | 18.43 ± 2.21 | 17.21 ± 2.37 | |
| Autumn | 16.96 ± 2.88 | 379.4 ± 25.41 | 421.30 ± 27.55 | 20.35 ± 2.95 | 19.86 ± 2.54 | |
| Winter | 16.64 ± 2.15 | 368.65 ± 22.66 | 356.61 ± 22.40 | 24.75 ± 2.52 | 22.34 ± 2.22 | |
| Persian Leek | Spring | 13.20 ± 1.22 | 531.19 ± 25.20 | 716.81 ± 37.91 | 5.21 ± 1.32 | 12.64 ± 2.43 |
| Summer | 12.10 ± 1.35 | 586.11 ± 29.68 | 772.45 ± 33.82 | 4.91 ± 1.11 | 11.95 ± 1.86 | |
| Autumn | 22.50 ± 1.66 | 511.42 ± 23.21 | 505.21 ± 26.55 | 12.44 ± 2.77 | 32.74 ± 2.44 | |
| Winter | 26.10 ± 1.47 | 507.17 ± 20.55 | 455.81 ± 25.81 | 15.23 ± 2.85 | 35.42 ± 2.65 | |
| Radish | Spring | 8.45 ± 1.93 | 429.63 ± 15.65 | 511.65 ± 26.88 | 5.43 ± 1.25 | 18.11 ± 2.32 |
| Summer | 8.24 ± 1.77 | 452.31 ± 16.45 | 568.33 ± 24.51 | 5.14 ± 1.10 | 17.25 ± 2.16 | |
| Autumn | 11.54 ± 2.24 | 341.5 ± 15.30 | 342.6 ± 21.30 | 12.88 ± 1.87 | 30.45 ± 2.95 | |
| Winter | 12.23 ± 2.35 | 314.25 ± 14.40 | 304.32 ± 19.65 | 13.27 ± 2.22 | 32.11 ± 2.86 | |
| Basil | Spring | 23.34 ± 3.22 | 341.95 ± 28.45 | 528.32 ± 31.30 | 17.35 ± 2.55 | 23.21 ± 2.89 |
| Summer | 24.41 ± 2.44 | 459.24 ± 24.36 | 604.81 ± 33.99 | 15.22 ± 2.41 | 27.55 ± 2.35 | |
| Autumn | 24.45 ± 3.67 | 375.1 ± 23.20 | 552.70 ± 29.90 | 27.65 ± 2.25 | 19.23 ± 2.55 | |
| Winter | 22.21 ± 3.65 | 270.4 ± 21.50 | 467.90 ± 28.60 | 34.41 ± 2.64 | 16.34 ± 2.67 | |
| Lettuce | Spring | 10.75 ± 2.14 | 325.11 ± 19.92 | 357.88 ± 22.35 | 4.65 ± 0.96 | 17.86 ± 2.34 |
| Summer | 11.21 ± 2.45 | 440.62 ± 18.53 | 452.20 ± 20.44 | 3.82 ± 0.99 | 20.26 ± 2.25 | |
| Autumn | 11.03 ± 1.48 | 351.2 ± 21.40 | 370.60 ± 22.20 | 9.86 ± 1.43 | 16.92 ± 2.33 | |
| Winter | 10.33 ± 1.96 | 250.6 ± 20.70 | 265.70 ± 21.90 | 11.52 ± 1.24 | 14.59 ± 2.21 | |
| WHO/FAO | 40 | - | 450 | 500 | 60 | |
The maximum Cu concentration was in Persian Leek (26.1 ± 1.47 mg/kg) in winter and in Basil (24.45 ± 3.67 mg/kg) in autumn. The maximum level for Mn was in Basil (34.41 ± 2.64 mg/kg) in winter and for Zn in Leek (35.42 ± 2.65 mg/kg) in winter. Also, the results (Table 2) show that the concentration of Fe metal in Coriander, Basil, and Persian Leek in all seasons, in Parsley and Lettuce in summer, and in Radish in spring and summer, was higher than the permissible values of FAO and WHO standards, and for other heavy metals, it was also in the lower range of FAO and WHO standards45. The results of statistical analysis based on ANOVA test show that in all types of ELVs, there was no significant difference between heavy metals concentrations, include As (P = 0.907), Cd (P = 0.234), Cr (P = 0.660), Ni (P = 0.857), Pb (P = 0.848), Fe (P = 0.307), Al (P = 0.151), Cu (P = 0.778), Mn (P = 0.101), and Zn (P = 0.180), in different seasons.
Changes in heavy metal concentration in ELVs in different seasons can be due to changes in environmental and climatic conditions, such as rainfall, temperature, and humidity during different seasons of the year, and human activities and discharge of industrial and agricultural wastewater into water and soil resources46. In a study by Ahmed et al., which was conducted on the pollution of water, soil, and ELVs with heavy metals in different seasons of the year in Bangladesh, it was shown that heavy metal concentration As, Cd, Cr, Pb, Cu, and Zn were higher than the permissible values, and their concentration was lower in wet seasons than in dry seasons46. This is consistent with some of the results of our study on the maximum concentration of pollution in Radish (Cr and As), and in Basil and Lettuce (Cr), which was in the winter season. Typically, during wet seasons, heavy metal concentration in water resources and vegetables decreases due to dilution effects caused by atmospheric precipitation. In dry seasons, due to reduced rainfall and increased evaporation in water resources, the concentration of metals in water resources and subsequently in vegetables increases47.
According to the results of the present study, the maximum concentration of ELVs contamination in Coriander and parsley (Cr), and in Leek (As) was observed in summer, which is consistent with the results of the study by Rahman et al.48,. Increased agricultural activities and irrigation of crops, especially ELVs, in the spring and summer seasons, and as a result, the increased possibility of heavy metals, especially As, being transferred from contaminated water to the roots and accumulating in the leaves of plants and vegetables, may play a role in the higher heavy metal concentration in the spring and summer seasons48,49. Of course, considering that in the present study, vegetable samples were collected and measured from the market, unhealthy and unhygienic conditions of storage and transportation of vegetables from the point of production to the market, and the presence of particles contaminated with heavy metals in the atmosphere and air near the place of growth and distribution market, may also play a role in the contamination of vegetables, especially vegetables whose heavy metal concentration was higher in the summer season5.
Edible ELVs contamination
Toxic heavy metal concentration in various ELVs across different seasons are shown in Fig. 1, and for other heavy metals in Fig. 2. The most contaminated ELVs with toxic heavy metals were order as follows: for As, Leek > Radish > Lettuce > Parsley > Coriander > Basil; for Cr, Lettuce > Parsley > Leek > Radish > Basil > Coriander, and for Pb, Radish > Leek > Coriander > Lettuce > Parsley > Basil (Fig. 1). The statistical analysis sing ANOVA showed that the difference between As, Cr, and Pb concentrations in ELVs were statistically significant (p ≤ 0.001). The post hoc test revealed that the concentration of As in Leek, Cr in Lettuce, and Pb in Radish was higher than in other ELVs, and this difference was statistically significant (p ≤ 0.001). In this study, the most contaminated ELVs with other heavy metals (Fig. 2) were Fe (in Coriander > Leek > Basil) and Al (in Leek > Parsley > Radish). The concentration of Cu was higher in Leek > Basil > Parsley, and for Zn it was Leek > Coriander > Radish. The ANOVA test results also showed that the difference in Fe and Al concentration among different types of ELVs were significant (p ≤ 0.001), and post hoc test showed that Al concentration in Leek and Fe in Coriander was higher than in the other ELVs and this difference was statistically significant (p ≤ 0.001). Studies have shown that leafy plants tend to store more heavy metals50. In a study by Zhong et al., heavy metal concentration in ELVs showed that ELVs contained higher heavy metals than root and fruit vegetables51. A study by Zhou et al. on heavy metal accumulation in plant species grown in soil in the Shijiazhuang region of China also showed that ELVs had the greatest ability to absorb and accumulate heavy metals32. As a result, the high Levels of heavy metals in ELVs such as lettuce, Leek, parsley, Coriander, and basil in the present study are consistent with these findings. The leaves of plants and vegetables are the primary and final organs for heavy metal accumulation. In fact, as heavy metals pass from the soil and water into the plant roots, they enter the stem and are ultimately stored in the leaves33. Also, ELVs have a higher ability to absorb heavy metals than other vegetables and plants due to their higher growth rate52.
Fig. 1.
Toxic heavy Metals concentrations in edible leafy vegetables in different seasons (a: As, b: Cd, c: Cr, d: Ni, e: Pb).
Fig. 2.
Other heavy metals concentrations in edible leafy vegetables in different seasons (a: Al, b: Cu, C: Fe, d: Mn, and e: Zn).
Annual concentrations of heavy metals
The mean and standard deviation of the annual concentration of heavy metals in ELVs are shown in Fig. 3. As illustrated in Fig. 3a, the average annual concentration of toxic heavy metals followed the order Cr > Ni > Pb > As > Cd in Coriander (3.37 ± 0.35, 1.27 ± 0.27, 1.16 ± 0.15, 0.8 ± 0.24, and 0.05 ± 0.06 mg/kg, respectively). In parsley, the order was Cr > Ni > Pb > As > Cd (6.83 ± 0.68, 1.53 ± 0.32, 0.97 ± 0.15, 0.78 ± 0.32, and 0.15 ± 0.04 mg/kg, respectively). For Leek, the order was As > Cr > Pb > Ni > Cd (10.91 ± 5.62, 6.07 ± 0.89, 2.65 ± 0.47, 1.01 ± 0.08, and 0.26 ± 0.04 mg/kg, respectively). In Radish, the order was Cr > Pb > Ni > As > Cd (5.44 ± 0.45, 4.22 ± 2.07, 0.97 ± 0.09, 0.81 ± 0.47, and 0.12 ± 0.01 mg/kg respectively). For Basil, the order was Cr > Pb > Ni > As > Cd (5.16 ± 1.84, 0.87 ± 0.08, 0.86 ± 0.10, 0.47 ± 0.06, and 0.16 ± 0.03 mg/kg respectively). Finally, in Lettuce, the order was Cr > Pb > As > Ni > Cd (10.38 ± 2.33, 1.1 ± 0.16, 0.88 ± 0.25, 0.82 ± 0.15, and 0.16 ± 0.04 mg/kg, respectively). The highest annual average toxic heavy metal concentration was observed for As in Leek, at 10.62 ± 5.62 mg/kg. This value is approximately100 times higher than the maximum permissible concentration set by the FAO and WHO standard (0.1 mg/kg). furthermore, the average annual concentration of As in all tested vegetables exceeded its permissible values. following As, the next highest annual average toxic metal concentration was found for Cr in Parsley, measuring 6.83 ± 0.68 mg/kg. The average annual concentration of Cr in all vegetables, except for Coriander, was higher than its permissible values (5 mg/kg). After As and Cr, the highest average concentration of the toxic metal Pb was found in Radish, at 4.22 ± 2.07 mg/kg. The average concentration of Pb in all tested vegetables also exceeded the permissible limits (0.3 mg/kg). The lowest concentration among tested metals in all vegetables was observed for Cd; however, its average concentration was still higher than the permissible limits (0.02 mg/kg). In general, the overall order of toxic heavy metal concentration across all vegetable was As > Cr > Pb > Ni > Cd. The most contaminated vegetables with toxic heavy metals were Leek > Lettuce > Radish > Parsley > Basil > Coriander.
Fig. 3.
Annual mean concentrations of heavy metals (a: toxic metals, and b: other metals) in edible leafy vegetables.
In Fig. 3b, the mean and standard deviation of the annual concentration of other heavy metals are shown. The average annual concentration of metals was related to Fe (in Coriander > Leek > Basil) and Al (in Leek > Parsley > Radish). The concentration of Cu metal was higher in Basil > Leek > Parsley > Coriander, and for Zn metal, it was also higher in Coriander > Radish > Leek, respectively. In general, the order of concentration of other metals in all vegetables was as Fe > Al > Zn > Cu > Mn, and the most polluted ELVs for other metals were as Coriander > Leek > Basil > Radish > Parsley > Lettuce. Studies have also shown that heavy metal concentrations in some regions of the world are higher than the FAO and WHO standards. In a study conducted by Quispe et al., in 2021, on heavy metal concentrations in vegetables, including mint, Coriander, garlic, and Leek in Peru, showed that Cr and Pb concentrations were higher than the standard values43. In a study by Alsafran et al., in Qatar, heavy metal accumulation in ELVs such as Coriander and parsley revealed that the concentrations of As, Cd, Cr, and Pb exceeded the WHO and FAO standards52. Similarly, a study by Tekle et al., in Hadnet region of Ethiopia examined ELVs irrigated with wastewater. The results indicated that the concentration of Pb, Al, Cr, Fe, and Cd were higher than the permissible values set by FAO53. In the Czech Republic, Vejvodová et al. investigated heavy metal concentrations in agricultural soil and vegetables from mining areas, finding them to be higher than the permissible and standard limits54. Additionally, Akan et al. measured heavy metal concentrations in vegetables from Borno State in northeastern Nigeria. The results showed that concentrations of Cr, Cu, Mn, Ni, Pb, and Zn exceeded the values recommended by the FAO and WHO standards33. In a study by Gebeyehu et al., in Ethiopia, heavy metal concentrations in soil and vegetables were found to be higher than the standard limits for As, Hg, Cd, Cr, and Pb50. These finding align with and support the results observed in our study.
High concentration of certain heavy metals, such as Cr and Pb, in ELVs can stem from pollution in soil and irrigation water, as well as atmospheric deposition55. Soil pollution allows to be absorbed through plant roots, eventually bioaccumulating in the leaves of the plant or ELVs38,46. Water contamination can arise from natural geological sources or human activities, including the discharge of agricultural, urban, or industrial wastewater used for irrigating ELVs, leading to the release metals like As, Cd, Cr, and Pb into water bodies56. Studies in southeastern regions, particularly Rafsanjan, indicate high heavy metal concentrations, especially As, attributed to mining activities, agricultural wastewater, and the specific geochemical properties of the local soil and bedrock40. Similarly, research by Yang et al., in China’s Dayeh region found higher concentration of Cu, Pb, Cd, and As were higher in soil and vegetable samples from mining areas compare to non-mining areas57. In our context,, the presence of mining activities in the Rafsanjan region and Kerman province likely contributes to the release of heavy metals such as As, Pb, and Cr into water resources, which are subsequent absorbed by ELVs irrigated with this polluted water24. Further confirmation comes from studies in southeastern Iran, where ELVs have be found to be contaminated with heavy metals. For instance, Abedi Sarvestani et al., investigated in Kerman, Iran. their finding revealed that levels of Pb, Cd, Fe, and Cu in ELVs exceeded the permissible limits set by WHO/FAO58. Given that vegetable samples in the present study were sourced from the market, factors such as unhealthy and unsanitary storage and transportation from the point of production to the market, along with atmosphere deposition of heavy metals-contaminated particles near growth and distribution areas, may also contributed to ELVs contamination5.
Health risk assessment
Average daily doses
Table 3 presents the average daily intake (ADI) values for each metal through consumption of raw ELVs by children and adults. The highest ADI among toxic metals was observed for As in Leeks, measuring 0.00146 mg/kg/day for children and 0.00141 mg/kg/day for adults. For other metals, the highest ADI values in children and adults were 0.16874 and 0.15497 mg/kg/day, respectively, associated with Fe in Lettuce. Overall, of total ELVs, the highest ADI values for toxic metals were Cr > As > Pb and for other metals they were Fe > Al > Cu in both children and adults. A study by Baghaie and Fereydoni on the risk assessment of heavy metals in ELVs like Lettuce, Basil, Coriander, and Parsley also reported the highest daily intake of As in Lettuce59. The elevated intake of metals such as Cr, As, Pb, Fe, and Al in ELVs like lettuce and spinach is due to their higher bioaccumulation rates in the edible leafy part of these vegetables, consequently leading to a higher human HRA60.
Table 3.
Average daily doses (ADDs) for each metal in vegetables in children and adults.
| Vegetables | As | Cd | Cr | Cu | Ni | Pb | Al | Fe | Mn | Zn |
|---|---|---|---|---|---|---|---|---|---|---|
| ADDs in children (mg/kg.day) | ||||||||||
| Coriander | 0.00011 | 0.00001 | 0.00045 | 0.00197 | 0.00017 | 0.00015 | 0.04581 | 0.10620 | 0.00174 | 0.00332 |
| Parsley | 0.00010 | 0.00002 | 0.00091 | 0.00235 | 0.00020 | 0.00013 | 0.05128 | 0.05495 | 0.00276 | 0.00259 |
| Leek | 0.00146 | 0.00003 | 0.00081 | 0.00247 | 0.00013 | 0.00035 | 0.07120 | 0.08168 | 0.00126 | 0.00309 |
| Radish | 0.00005 | 0.00001 | 0.00036 | 0.00067 | 0.00006 | 0.00028 | 0.02563 | 0.02878 | 0.00061 | 0.00163 |
| Basil | 0.00013 | 0.00004 | 0.00138 | 0.00629 | 0.00023 | 0.00023 | 0.09645 | 0.14358 | 0.00631 | 0.00576 |
| Lettuce | 0.00041 | 0.00007 | 0.00484 | 0.00505 | 0.00038 | 0.00051 | 0.15955 | 0.16874 | 0.00348 | 0.00089 |
| ADDs in adults (mg/kg. Day) | ||||||||||
| Coriander | 0.00010 | 0.00001 | 0.00043 | 0.00190 | 0.00016 | 0.00015 | 0.04417 | 0.10241 | 0.00167 | 0.00320 |
| Parsley | 0.00010 | 0.00002 | 0.00088 | 0.00226 | 0.00020 | 0.00012 | 0.04945 | 0.05298 | 0.00266 | 0.00250 |
| Leek | 0.00141 | 0.00003 | 0.00078 | 0.00238 | 0.00013 | 0.00034 | 0.06865 | 0.07876 | 0.00121 | 0.00298 |
| Radish | 0.00003 | 0.00000 | 0.00023 | 0.00043 | 0.00004 | 0.00018 | 0.01648 | 0.01850 | 0.00039 | 0.00105 |
| Basil | 0.00008 | 0.00003 | 0.00088 | 0.00405 | 0.00015 | 0.00015 | 0.06200 | 0.09230 | 0.00406 | 0.00370 |
| Lettuce | 0.00038 | 0.00007 | 0.00445 | 0.00464 | 0.00035 | 0.00047 | 0.14652 | 0.15497 | 0.00320 | 0.00082 |
Non-carcinogenic risk assessment
Table 4 presents the hazard quotient (HQ) values for the non-carcinogenic risk of each metal in ELVs consumed by children and adults. The highest HQ values for metals were As in Leek (4.8733 in children, 4.6993 in adults), Lettuce (1.3689 in children, 1.2571 in adults), and Cr in Lettuce (1.6139 in children, 1.4821 in adults), all of which were higher than 1 (indicating a high non-carcinogenic risk). The total HQ (THQ) values for the aggregate consumption of ELVs in children are shown in Fig. 4a, ranked as As > Cr > Fe > Cu > Pb > Al > Mn > Cd > Ni > Zn. In adults, the ranking was similar, with only the positions of Pb and Cu metals shifted. Overall, the total HQ values for total vegetable consumption in both children and adults were higher than 1 for As (7.5461 in children, and 7.0207 in adults) and Cr (2.9168 in children, and 2.5523 in adults). Figure 4b shows the HI values for all heavy metals in the non-carcinogenic risk assessment for each type of ELVs consumed in children and adults. The highest HI values were associated with the consumption of Leek (5.57 in children and 5.37 in adults), Lettuce (3.85 in children and 3.51 in adults), Basil (1.61 in children and 1.04 in adults), Parsley (0.97 in children and 0.94 in adults), Coriander (0.86 in children and 0.83 in adults), and Radish (0.49 in children and 0.32 in adults), respectively. This indicates that the HI values for Leek, Lettuce, and Basil were greater than 1 (Fig. 5).
Table 4.
HQ values in non-carcinogenic risk assessment for metals exposure by edible leafy vegetables in children and adults.
| Vegetables | As | Cd | Cr | Cu | Ni | Pb | Al | Fe | Mn | Zn |
|---|---|---|---|---|---|---|---|---|---|---|
| HQ in children | ||||||||||
| Coriander | 0.3567 | 0.0070 | 0.1499 | 0.0492 | 0.0085 | 0.0429 | 0.0458 | 0.1517 | 0.0377 | 0.0111 |
| Parsley | 0.3467 | 0.0203 | 0.3037 | 0.0586 | 0.0102 | 0.0358 | 0.0513 | 0.0785 | 0.0600 | 0.0086 |
| Persian Leek | 4.8733 | 0.0343 | 0.2698 | 0.0617 | 0.0067 | 0.0981 | 0.0712 | 0.1167 | 0.0274 | 0.0103 |
| Radish | 0.1806 | 0.0077 | 0.1209 | 0.0169 | 0.0032 | 0.0782 | 0.0256 | 0.0411 | 0.0133 | 0.0054 |
| Basil | 0.4200 | 0.0420 | 0.4587 | 0.1574 | 0.0115 | 0.0643 | 0.0964 | 0.2051 | 0.1371 | 0.0192 |
| Lettuce | 1.3689 | 0.0735 | 1.6139 | 0.1264 | 0.0192 | 0.1426 | 0.1595 | 0.2411 | 0.0757 | 0.0030 |
| HQ in adults | ||||||||||
| Coriander | 0.3439 | 0.0068 | 0.1445 | 0.0475 | 0.0082 | 0.0413 | 0.0442 | 0.1463 | 0.0364 | 0.0107 |
| Parsley | 0.3343 | 0.0196 | 0.2928 | 0.0565 | 0.0099 | 0.0346 | 0.0495 | 0.0757 | 0.0578 | 0.0083 |
| Persian Leek | 4.6993 | 0.0331 | 0.2601 | 0.0594 | 0.0064 | 0.0946 | 0.0687 | 0.1125 | 0.0264 | 0.0099 |
| Radish | 0.1161 | 0.0049 | 0.0778 | 0.0108 | 0.0021 | 0.0503 | 0.0165 | 0.0264 | 0.0086 | 0.0035 |
| Basil | 0.2700 | 0.0270 | 0.2949 | 0.1012 | 0.0074 | 0.0413 | 0.0620 | 0.1319 | 0.0882 | 0.0123 |
| Lettuce | 1.2571 | 0.0675 | 1.4821 | 0.1160 | 0.0176 | 0.1310 | 0.1465 | 0.2214 | 0.0695 | 0.0027 |
Fig. 4.
Total HQ and HI values in non-carcinogenic risk assessment for a: each metal in total vegetables, b: each edible leafy vegetable in total heavy metals in child and adults.
Fig. 5.
HI values in non-carcinogenic risk assessment for edible leafy vegetables in a: children and b: adults.
Risk assessment studies on vegetables indicate that HQ and HI values above one signify a high risk of health concerns for individuals exposed to these vegetables43. This implies that the risk of exposure to As in our study is 7 times higher than the permissible limit, denoting a very high non-carcinogenic risk. In the study of Alsafran et al., which assessed the risk and accumulation of heavy metals in ELVs such as Coriander and parsley, it was demonstrated that HQ values for the heavy metals As and Cu in adults were greater than 1 for these ELVs. Furthermore, HI values for Coriander and parsley also exceeded 1 for these two metals52. A study conducted by Zhou et al., in China, focusing on heavy metal accumulation in plant species cultivated in soil and HRA, yielded results showing THQ values of 4.12 and 5.41 for adults and children, respectively, through the consumption of ELVs. This indicated a high risk of health risks for residents due to the vegetable consumption32. Similarly, a study by Abedi Sarvestani et al., on the assessment of heavy metals revealed that the total HQ or HI values for the non-carcinogenic risk from consumption ELVs such as parsley, Coriander, Persian Leek, and basil in children and adults were higher than one58. In the research by Pavlíková et al., the highest non-carcinogenic risk and HI values were linked to the consumption of lettuce61. In the study by Baghaie and Fereydoni, an assessment of the risk of heavy metals associated with the consumption of ELVs such as lettuce, basil, Coriander, and parsley indicated that the highest HQ values in the risk assessment were related to As in lettuce, while the lowest were related to Coriander. This is consistent with the results of our study59. The high health risk associated with consuming ELVs like lettuce and Leeks may be attributed to the high bioaccumulate capacity of these vegetables for heavy metals62. Furthermore, the pollution of water and soil resources in the region could contribute the heavy metal accumulation in ELVs, particularly lettuce and Persian Leek, consequently leading to their high health risk40. Additionally, the elevated health risk posed by As and Cr in ELVs might stem from the bioavailability and high solubility of As in water can facilitate its easy absorption by the roots of vegetables61.
The finding also indicate that HQ and HI values were higher in children compare to adults (Fig. 5). His observation align with similar research43 and can be attribute to factors such as differences in body weight and duration of exposure between children and adults37. Children’s heightened vulnerability stems from higher intake-to-weight ratio32,61.
Carcinogenic risk assessment
Table 5 presents the carcinogenic risk (CR) values from the assessment of exposure to toxic metals As, Cd, Cr, Ni, and Pb through ELVs in children and adults. The highest CR values were observed for Cr (2.42 × 10− 3 in children and 2.22 × 10− 3 in adults) in Lettuce, As (2.19 × 10− 3 in children and 2.11 × 10− 3 in adults) in Leek, Cr (6.88 × 10− 4 in children and 4.42 × 10− 4 in adults) in Basil, and Ni (6.53 × 10− 4 in children and 5.99 × 10− 4 in adults) in Lettuce. The total CR values for all ELVs in both age groups (Fig. 6a) were ranked for toxic metals Cr > As > Ni > Cd > Pb, respectively, which was 4.38 × 10− 3, 3.40 × 10− 3, 2.02 × 10− 3, 7.02 × 10− 5, and 1.41 × 10− 5 in children and 3.83 × 10− 3, 3.16 × 10− 3, 1.75 × 10− 5, and 1.20 × 10− 5 in adults, respectively. Figure 6b illustrated the ILCR for total toxic metals across each type of consumed vegetable for children and adults. Among children, the highest ILCR values in consumed ELVs were associated with Lettuce (3.72 × 10− 3) followed by Leek (2.84 × 10− 3) Basil (1.29 × 10− 3) Parsley (9.68 × 10− 4) Coriander (6.78 × 10− 4) Radish (3.78 × 10− 4). In adults, the order was Lettuce (3.42 × 10− 3) Leek (2.74 × 10− 3) Parsley (9.33 × 10− 4) Basil (8.27 × 10− 4) Coriander (6.54 × 10− 4) Radish (2.43 × 10− 4). For all vegetables, the ILCR values exceeded 1 × 10− 4 (Fig. 7). In a study conducted by Quips et al., on the health risk associated with heavy metals exposure from consumption of vegetables like mint, Coriander, garlic, and Leeks in Peru, it was found that exposure to As through Leeks and Coriander posed a significant risk to both children and adults43. Similarly, Alsafran et al., reported that the Carcinogenic Risk values for heavy metals such as As, Cr, and Ni in adults consuming Coriander and parsley exceeded 1 × 10–452. Furthermore, research by Zhong et al., indicated that individuals face high exposed Levels of Pb, Cd, and Hg when consuming vegetables51. A study by Abedi Sarvestani et al., showed that the ILCR values for Pb and Cd from ELVs consuming such as parsley, Coriander, Persian Leeks, and basil were also found to be in the unacceptable and high range for both children and adults (56). In the study by Shekoohiyan et al., the risk of carcinogenesis due to exposure to heavy metals As, Cd, Pb, and Zn through the consumption of lettuce and Leek was determined to be high. The highest ILCR values were specifically related to lettuce and Leek, respectively37. Consist with these finding, other studies also report a high carcinogenic risk of heavy metals, especially As, Cr, and Ni, through consumption of ELVs like lettuce, Leek, basil, and parsley. The high risk of carcinogenesis, especially from As and Cr in ELVs, may be linked to soil and climate pollution in the region, as well as mining and related activities40,63. The high carcinogenesis risk of As from vegetables consumption can lead to the occurrence of various cancers, including liver, kidney, and bladder27. Therefore, it is recommended that regional officials increase their attention to ELVs, distributed within the city, implement continuous monitoring of ELVs for heavy metals content, and ensure necessary supervision over their distribution.
Table 5.
CR values in carcinogenic risk assessment for heavy metals exposure by edible leafy vegetables in children and adults.
| Vegetables | As | Cd | Cr | Ni | Pb |
|---|---|---|---|---|---|
| CR in children | |||||
| Coriander | 1.61 × 10− 4 | 2.66 × 10− 6 | 2.25 × 10− 4 | 2.88 × 10− 4 | 1.31 × 10− 6 |
| Parsley | 1.56 × 10− 4 | 7.73 × 10− 6 | 4.56 × 10− 4 | 3.47 × 10− 4 | 1.10 × 10− 6 |
| Persian Leek | 2.19 × 10− 3 | 1.30 × 10− 6 | 4.05 × 10− 4 | 2.26 × 10− 4 | 3.00 × 10− 6 |
| Radish | 8.13 × 10− 5 | 2.91 × 10− 6 | 1.81 × 10− 4 | 1.10 × 10− 4 | 2.39 × 10− 6 |
| Basil | 1.89 × 10− 4 | 1.60 × 10− 5 | 6.88 × 10− 4 | 3.91 × 10− 4 | 1.97 × 10− 6 |
| Lettuce | 6.16 × 10− 4 | 2.79 × 10− 5 | 2.42 × 10− 3 | 6.53 × 10− 4 | 4.36 × 10− 6 |
| CR in adults | |||||
| Coriander | 1.55 × 10− 4 | 2.57 × 10− 6 | 2.17 × 10− 4 | 2.78 × 10− 4 | 1.26 × 10− 6 |
| Parsley | 1.50 × 10− 4 | 7.45 × 10− 6 | 4.39 × 10− 4 | 3.35 × 10− 4 | 1.06 × 10− 6 |
| Persian Leek | 2.11 × 10− 3 | 1.26 × 10− 5 | 3.90 × 10− 4 | 2.18 × 10− 4 | 2.89 × 10− 6 |
| Radish | 5.22 × 10− 5 | 1.87 × 10− 6 | 1.17 × 10− 4 | 7.09 × 10− 4 | 1.54 × 10− 6 |
| Basil | 1.22 × 10− 4 | 1.03 × 10− 5 | 4.42 × 10− 4 | 2.51 × 10− 4 | 1.26 × 10− 6 |
| Lettuce | 5.66 × 10− 4 | 2.57 × 10− 5 | 2.22 × 10− 3 | 5.99 × 10− 4 | 4.01 × 10− 6 |
Fig. 6.
Total CR and ILCR values in carcinogenic risk assessment for a: each metal in total vegetables, b: each edible leafy vegetable in total metals, in child and adults.
Fig. 7.
ILCR values in carcinogenic risk assessment for edible leafy vegetables in a: children and b: adults.
Conclusion
In the study conducted in Rafsanjan city during 2024, the concentrations of various heavy metals in ELVs distributed and health risks assessment of heavy metals resulting from the consumption of these ELVs - specifically Coriander, parsley, basil, Leek, radish, and lettuce - were measured and evaluated across four seasons. Based on the obtained results, the maximum toxic heavy metal concentrations in the Leek species followed the order As > Cr > Pb > Ni > Cd; in the Radish species, it was Cr > Pb > Ni > As > Cd; and in the Lettuce species it was Cr > Pb > As > Ni > Cd; respectively. The maximum concentrations of other studied metals in all consumed ELVs showed the order Fe ˃ Al. The most contaminated ELVs with toxic As were Leek ˃ Lettuce ˃ Radish ˃ Coriander ˃ Parsley ˃ Basil; for Cr, they were Lettuce > Parsley > Leek > Radish > Basil > Coriander; and for Pb, they were Radish > Leek > Coriander > Lettuce > Parsley > Basil. The highest average annual concentrations of other heavy metals were related to Fe (in Coriander ˃ Leek ˃ Basil) and Al (in Leek ˃ Parsley > Radish).
The highest THQ values for total vegetable consumption in children were related to As ˃ Cr ˃ Fe ˃ Cu ˃ Pb ˃ Al ˃ Mn ˃ Cd ˃ Ni ˃ Zn. In adults, only the rank of Pb and Cu was shifted. The highest HI values were related to Leek ˃ Lettuce ˃ Basil ˃ Parsley ˃ Coriander ˃ parsley, in both age groups. The HI values in Leek, lettuce, and basil were greater than 1 (indicating a high non-carcinogenic risk). The highest total CR values in all ELVs for both age groups were related to heavy metals Cr ˃ As ˃ Ni ˃ Cd ˃ Pb, which were in the high CR range for Cr, As, and Ni. Additionally, the highest ILCR values in consumed ELVs by children were related to Lettuce ˃ Leek ˃ Basil ˃ Parsley ˃ Coriander ˃ Radish, and in adults, they were related to Lettuce ˃ Leek ˃ Parsley ˃ Basil ˃ Coriander ˃ Radish. For all ELVs, ILCR values were in the high carcinogenic risk range. Therefore, continuous monitoring and surveillance of ELVs in terms of heavy metals is recommended to reduce exposure of children and adults in the study area, as well as in other parts of the world. However, future studies are recommended in the region and other relevant areas to gather stronger evidence for decision making.
Acknowledgements
This study is the result of a project by the National Institute for Research and Development of Medical Sciences (NIMAD) of Iran, project number 4021345, which is approved by the ethics code IR.RUMS.REC.1402.129 at Rafsanjan University of Medical Sciences. The financial support of the National Institute for Research and Development of Medical Sciences (NIMAD) is gratefully acknowledged.
Author contributions
**Hadi Eslami: ** Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Supervision, writing – original draft, writing – review and editing**Ali Zare: ** Data curation, Investigation, Methodology, writing – original draft, writing – review and editing**Mahrokh Jalili: ** Formal analysis, Methodology, writing – original draft, writing – review and editing.
Funding
This research was supported by the National Institute for Research and Development of Medical Sciences (NIMAD) of Iran.
Data availability
The data that support the findings of this study are available on request from the corresponding author.
Declarations
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available on request from the corresponding author.