Quantification and Reduction in Heavy Metal Residues in Some Fruits and Vegetables: A Case Study Galați County, Romania

Abstract

One of the main issues for sustainable global development with high priority is food security. The negative effects of contaminants on crop quality have threatened both food security and human health. Long-term heavy metal exposure from food, drinking water, or other occupational sources causes serious problems, such as kidney failure, hepatotoxicity, and neurotoxicity. This study was conducted to determine the concentrations of three toxic trace elements (As, Cd, Pb) and one microelement (Zn) in fruits and vegetables using ICP-MS, and it also sought to reduce the concentrations of metals by washing with vinegar (5% and 10% acetic acid). The potential of vinegar to influence heavy metal contents may be due to its effect on pH values that influence the solution chemistry of the heavy metals, such as hydrolysis, redox reactions, precipitation, and availability of heavy metals. Sample origin has a significant influence in terms of metal accumulation; values up to 35%, 68%, 67%, and 3% lower were recorded in the case samples originating from amateur farmers (for As, Cd, Pb, and Zn, respectively). Regarding the efficiency of the vinegar, As and Zn recorded levels up to 8% lower for samples washed with 10% vinegar, and Cd showed levels up to 20% lower for samples washed with 10% vinegar, while Pb did not register any differences.

1. Introduction

Metals are chemical elements with high electrical conductivity, high gloss, and malleability, which voluntarily lose their electrons to form cations [1]. In the atmosphere, the distribution of metals is monitored by studying various environmental factors [2]. In general, heavy metals are those metals that have a specific density of more than 5 g/cm³ and negatively affect living organisms and the environment [3], but any toxic metal may be called a heavy metal, irrespective of their atomic mass or density [4]. Any species of metal or metalloid may be considered a contaminant when its presence is undesirable or its form or concentration causes harm to humans or affects the environment [4]. Such metals/metalloids include As, Cd, Cr, Cu, Pb, Hg, Ni, Se, Ag, and Zn [4]; other less common metallic contaminants include Al, Cs, Co, Mn, Mo, Sr, and U [5].

Living organisms need various amounts of heavy metals (e.g., the biological function of Cd in marine diatoms [6] or the role of Fe, Co, Cu, Mn, Mo, and Zn in humans [4]); however, all metals are toxic at higher concentrations [7]. Excessive concentrations can seriously harm the human body [4]; the main threats to human health are the heavy metals Pb, Cd, Hg, and As (As is a metalloid, but is usually classified as a heavy metal) [3]. In the case of V, W, and Cd, these elements are normally toxic to certain organisms, but under certain conditions, they can be beneficial [4]. Heavy metals are among the most important contaminants in the food chain; consumed even in low concentrations, they trigger serious health effects [8].

In the era of global warming, a full understanding of the mechanisms underlying plant resistance or tolerance to abiotic and biotic factors is extremely important, due to the increased mobility of pollutants in the environment [9]. The irrational and disproportionate use of chemical fertilizers, pesticides, and polluted water for irrigation are the main factors responsible for heavy metal contamination of plants [10]. Plants have developed several mechanisms to avoid the toxicity of heavy metals [11]. Plants can survive and grow on soil contaminated with heavy metals because they manage to prevent the absorption of heavy metals in the aerial parts or maintain a constant and low metal concentration over a broad range of metal concentration in soil by holding metals in their roots (metal excluders) [12], accumulate metals in their aerial tissues due to the production of metal binding in non-sensitive parts (metal indicators) [13], and concentrate metals in their aerial parts at levels far exceeding the concentrations in soil (hyperaccumulators) [14]. Through the phytoremediation process, plants provide a cost-effective approach with minimal environmental safety concerns other than chemical or physical processes for the remediation of contaminated areas [15].

Fruits and vegetables are considered imported components of the human diet, both in terms of quantities consumed and their nutritional values [16]. The effects of the contamination of vegetables and fruits with heavy metals cannot be ignored or underestimated. Fruits and vegetables are rich sources of vitamins, minerals, and fiber and have beneficial antioxidant effects [17]. However, the consumption of fruits and vegetables with high concentrations of heavy metals can pose a risk to human health, which means that determining the level of heavy metal contamination in food is one of the most important aspects of ensuring the quality of fruits and vegetables [18,19].

Within the European Union (EU), the production and marketing of fresh vegetables and fruits have been covered by the rules of the common organization of agricultural markets [20]. The quality and control of fresh fruits and vegetables is regulated in the Commission Regulation (EC) No. 1580/2007 of 21 December 2007 [21]. EU Member States are required to carry out physical checks of fresh fruit and vegetables at each stage of marketing [20]. Moreover, EU consumers expect the fruits and vegetables they eat to be safe, and they also need to have access to relevant information to make the best-informed choices [20]. This problem has been solved by introducing maximum acceptable limits (MAL) for concentrations of hazardous substances in fresh fruits and vegetables in accordance with the Commission Regulation (EC) No. 1881/2006 of 19 December 2006 [22]. Additionally, the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO) set MAL for certain contaminants (Pb and Cd) in fresh fruits and vegetables [23]. Some EU countries have set their own MAL for elements and substances that cannot be exceeded in fresh fruits and vegetables. Supplementary Table S1 presents the MAL concentrations of hazardous substances in fruits and vegetables sold in Romania [24,25].

A review of the most important scientific papers is presented in Supplementary Table S2. It has been observed that the most common analytical methods successfully applied in routine laboratories for determining the elements in fruits and vegetables are based on atomic absorption spectroscopy (AAS), inductively coupled plasma-mass spectrometer (ICP-MS), microwave and inductively coupled plasma optical emission spectroscopy (ICP-OES), microwave and inductively coupled plasma atomic emission spectrometry (ICP-AES), flame atomic absorption spectrometry FAAS, inductively coupled plasma-mass spectrometer (ICP-MS), and energy-dispersive X-ray fluorescence (ED-XRF). The concentration levels of the elements are presented in Supplementary Table S3. The majority of papers focused on studies on vegetables and fruits coming from vegetable and fruit markets, while studies on samples from amateur farms were few (Supplementary Table S2).

The present study was intended (1) to quantify the levels of heavy metals (As, Cd, Pb) and microelement (Zn) in common fruits and vegetables obtained from the local market (vegetable and fruit market and from amateur farmers); (2) determining whether the sample’s origin was decisive in terms of the heavy metal’s concentration, and (3) suggest possible methods for heavy metal removal. The obtained data could help policies and programmers to ensure safety and food quality by eliminating threats of heavy metal contamination.

2. Materials and Methods

2.1. Fruit and Vegetable Samples

A total of 80 fruit and vegetable samples (45 samples from the vegetables and fruit market and 35 samples from amateur farmers) were purchased randomly from August 2020 to December 2021 in necessary quantities, and packed in clean polyethylene bags to carry to the laboratory for future processing. This research sought to determine whether the cultivation of these fruits and vegetables in an intensive system or whether local farms managed by amateur farmers influenced the bioavailability and bioaccumulation of heavy metals. To obtain a broader picture and to identify whether the cultivation method could influence the accumulation of heavy metals, samples of fruit and vegetables from specially designed areas were purchased (areas especially arranged and authorized for marketing these foods) from vegetable and fruit markets (e.g., food markets, grocery stores, and market areas where people living in the city had faster access to shopping) and local farms (e.g., gardens and areas arranged by amateur farmers with direct sales) situated in Tecuci (45°50′48″ N and 27°25′40″ E), Matca (45°51′24″ N and 27°32′11″ E), and Târgu Bujor (45°52′10″ N and 27°55′8″ E); the harvest areas were part of Galați county in southeastern Romania (45°26′22″ N and 28°2′4″ E). These areas are famous at the national level for their fruits and vegetables, which are also exported to EU countries. The collected samples were mainly grown in rural areas of Galați city and transported to the city markets for public consumption. Fruit and vegetable samples were harvested and processed directly for analysis within 1 to 3 days. In this case, only edible parts were used for analysis. The collected food items were fruiting vegetables, fruits, leafy vegetables, bulbs, and root vegetables. More information about the analyzed samples are presented in Supplementary Table S4.

2.2. Sample Preparation and Digestion Using Microwave Digestion System

Fruit and vegetable samples were carefully washed under tap water to remove dust, dirt, and possible organisms. Samples were not washed with distilled water, due to the need to identify the possibility of reducing the concentrations of heavy metals by washing with tap water. To identify the possibility of reducing the concentrations of heavy metals by washing with tap water, no samples were washed with distilled water. Depending on the initial heavy metal concentrations obtained from fruit and vegetable samples washed with tap water, it was decided which samples should be washed with vinegar. Washing of fruit and vegetable samples in vinegar (5% or 10% acetic acid) solution was carried out by immersing the samples in a glass bowl with vinegar. The washing times of the samples varied between 5 min and 10 min at 30 °C, depending on the size and number of the samples. Sample preparation and digestion methods for fruit and vegetables were carried out as described earlier by Bora et al. (2020) [26], with some modifications. Only the edible parts of each fruit and vegetable sample were used for analysis. Damaged or spoiled parts of the fruit and vegetable samples were removed before sample preparation as a simulation of the real food preparation for human consumption. Fresh samples were weighed and then cut using a clean knife into small proportions for drying at 105 °C using an FD 53 Binder (Darmstadt, Germany). The samples were considered dry when they reached a stable weight, so the completed drying of the analyzed samples was performed in 72 h to 92 h. Dry samples were ground using a Retsch 110 automatic mill (Darmstadt, Germany) and passed through a 2 mm sieve to obtain very fine particles. Trace element concentrations of fruit and vegetable samples were determined on a dryweight basis and converted to freshweight basis for comparison with the maximum levels (MLs) for contaminants in foods. Dried and ground samples were stored in pre-labeled polyethylene bags until digestion. The method for microwave digestion using a Milestone START D Microwave Digestion System (Sorisole, Italy) was optimized in a previous work by Bora et al. (2015) [26]: 0.5 g sample of fruit or vegetable and 7 mL 65% nitric acid (HNO₃) + 2 mL hydrogen peroxide (H₂O₂) were placed in a clean Teflon digestion vessel, and the vessel was closed tightly and placed in the microwave system (Milestone START D Microwave Digestion System). The digestion was carried out with the program described in Supplementary Table S5.

2.3. General ICP-MS Instrumental Parameters of Analysis

Analytical measurements of the elements (⁶⁵Zn, ⁷⁵As, ¹¹¹Cd, ²⁰⁸Pb) were performed using an ICP-MS (iCAP Q ICP-MS Thermo Fisher Scientific, Waltham, Massachusetts, USA), equipped with an ASX-520 autosampler, a micro-concentric nebulizer, cones (the instrument used a Ni sampler and Ni skimmer cones), and a peristaltic sampled delivery pump, and running a quantitative analysis mode. A nebulizer fitted to a cyclonic spray chamber was used for introducing the sample solutions into ICP-MS plasma; the standard ICP-MS torch includes a 1.5 mm diameter injector. Before the quantitative evaluation of the sample, the ICP-MS was allowed to equilibrate (from the star up) for at least 45 min; during this time the experimental conditions and mass calibration of the instrument were checked. A short-time stability test was performed using a tuning standard solution (TUNE B iCAP Q Ba, Bi, Ce, Co, In, Li, U–1.0 µg/L (each) in 2% HNO₃ + 0.5 HCl)) covering the whole range of masses. The role of this autotune was to allow optimizations of the sampling zone of the plasma to provide a compromise between high sensitivity, optimizations of ions optics voltage, and low levels of cluster ions and doubly charged ions. The ICP-MS was optimized daily to give a maximum sensitivity for M⁺ ions, and the double ionization and oxides were monitored by the means of the ratio between Ba²⁺/ Ba⁺ and Ce²⁺/ CeO⁺, respectively; these were always less than 2%. The argon (Ar 5.0) and helium (He 6.0) used were 99.99% purity (Messer, Austria). Each sample was analyzed in duplicate, and each analysis consisted of seven replicates. The methodology used to measure these parameters has been presented and optimized in previous work [26,27]. The operating parameters of the ICP-MS device are given in Supplementary Table S6.

2.4. Reagents and Solutions

All reagents used were analytical grades: 65% HNO₃–supra pure for trace analysis (Merk, Darmstadt, Germany), and H₂O₂ ≥ 30% for trace analysis (Sigma-Aldrich, Steinheim, Germany). The analysis was made using the external standard calibration method, after an appropriate dilution and ICP-MS technique [26,27]. Each sample was analyzed in duplicate, and each analysis was prepared in three replicates [26,27]. The standard solution used for generating the calibration curve and for the calibration of ICP-MS was high purity ICP Multi-Element Standard Solution XXI CertiPUR (Merk, Darmstadt, Germany). Ge, Tb, Rh, and Sc in supra pure 1% HNO₃ (Merk, Darmstadt, Germany) were used as internal standards (the internal standard was added to the level of 50 µg/L to all samples, blanks, and standards). Ultrapure water used for sample (pre)preparation was obtained from Milli-Q Integral Ultrapure Water-Type 1 (maximum resistivity of 18.2 MΩ × cm⁻¹). Vinegar (5% and 10%) obtained from white wine was used to wash the fruit and vegetable samples.

2.5. Quality Control of the Chemical Analyses

Appropriate quality assurance procedures and precautions were taken to ensure the reliability of the results. The glassware used for the storage or processing of the samples was properly cleaned, and the handling of the samples was performed carefully to avoid cross-contamination. All glassware and plasticware/polyethylene bottles used for sample preparation and storage were cleaned by soaking in 10% v/v HNO₃ for 24 h and rinsing at least three times with ultrapure water (maximum resistivity of 18.2 MΩ × cm⁻¹) [26,27]. The Teflon vessel used for sample digestion was cleaned by soaking in 5% HNO₃ for more than 24 h, then rinsed with Milli-Q water and dried at 105 °C in the oven.

To implement the quality control of the chemical analyses, the blank method was used through the complete preparation and analytical procedure. The blank spike duplicate (BSD) was performed in triplicate to confirm the procedure was working within the established control limits. Control samples and working standards were prepared daily from the intermediate standards (the intermediate solutions stored in polyethylene bottles were prepared from the stock solution) [26,27]. Before starting the heavy metal analysis sequence, mass calibration was performed using a 250 mL setup solution (Setup Solution iCAP Q Be, Zn, Cu, Ni, Al, Ga, Mg, Co, Li, Sc, Ag, Mn, Sr, Ba, Tl, Bi, Ce, Cs, Ho, In, Rh, Ta, Tb, U, Y—3–35 µg/L in 2% HNO₃), and the relative standard deviation (RSD < 5%) was checked using a tuning solution 500 mL (TUNE B iCAP Q Ba, Bi, Ce, Co, In, Li, U—1.0 µg/L (each) in 2% HNO₃ + 0.5 HCl) purchased from Thermo Scientific. The certified reference materials (CRM) were used to check the accuracy of the analyses, the methodology used for verifying the accuracy consisted of replicating analyses of known sample concentrations of CRMs, and the obtained values ranged between 0.1% and 4.0%, depending on the element, the global recovery for each element was between 97% and 102%.

To establish the quality control of the analyses performed, blanks and triplicates samples (n = 3) were analyzed during the procedure and the variation coefficient was kept under 5%. One calibration blank (1% HNO₃) was used to establish the analytical curve, and detection limits (ppb) were determined by the calibration curve method. Method blanks were used to check for possible sample contamination during the sample’s preparation procedure. For each analyzed sample, the spike method was performed by analyzing the control and the standard samples. Limit of detection (LoD) and limit of quantification (LoQ) were calculated using the following mathematical equations: LoD = 3 × SD/s and LoQ = 10 × SD/s, where SD = estimation of the standard deviation of the regression lines, and s = slope of the calibration curve). The calibration standard solution was prepared from multi-element standard solution ICP Multi-Element Standard Solution XXI CertiPUR (obtained from Merk, Darmstadt, Germany), in seven concentrations ranging between 2.5 µL, 5 µL, 10 µL, 25 µL, 50 µL, 100 µL, and 250 µL. As presented, the accuracy of the analytical procedure was investigated by spiking a suitable known amount of the analyte metal into a test portion of the sample and analyzing the spiked test portion along with the original samples [28], while the precision of the analytical procedure was expressed as RSD% of the triplicate analyses [29]. The analytical procedure, calibration standards, precision, quality control, and accuracy of the analysis were optimized in previous work [26]. The recovery assays for fruit and vegetable samples of 25 µL concentration gave average recovery levels R% between 90.04% and 112.36% for three replicates of this level of concentration (n = 3). LoD and LoQ (instrumental conditions) for As, Cd, Pb, and Zn using an ICP-MS device are given in Supplementary Table S7.

2.6. Statistical Analysis

Average, median, and relative standard deviation were calculated using Excel 365 (Microsoft, New York, NY, USA) and Addinsoft version 15.5.03.3707 (Microsoft, New York, NY, USA. The precisions of the data were calculated and expressed as standard deviation (SD), and the data were subjected to statistical analysis by using SPSS Version 24 (SPSS Inc., Chicago, IL, USA) and was later presented in term of mean (three replications) and standard deviation. The recorded data were subjected to two-way analysis of variance (ANOVA) to assess the influence of different variables on the concentrations of heavy metals in fruits and vegetables tested. Analysis of variance (ANOVA) and the average separation were performed with the Duncan test at p ≤ 0.005 using SPSS Version 24 (SPSS Inc., Chicago, IL, USA).

3. Results and Discussion

3.1. Heavy Metal Concentrations in Fruits and Vegetables

3.1.1. Arsenic

Research has shown that As is not considered an essential element for humans, but in the case of animals, at ultra-trace levels, As was reported to play some beneficial roles [30]. However, long-term exposure to concentrations above the MAL of As can lead to cardiovascular disease, diabetes, oxidative stress, and various types of cancers [31]. As is genotoxic, and affects cell proliferation and signaling, transcription and repair of DNA, epigenetic regulation, and apoptosis [30,32]. The As concentration in the analyzed samples ranged from below LoQ (LoQ for As: 0.711 µg/L) to 388.86 µg/kg FW with an average value of 182.97 µg/kg FW (for fruiting vegetables) (

Table 1. Mean and standard deviation for heavy metals concentration (µg/kg FW) in fruiting vegetables, fruits, leafy vegetables, bulbs, and root vegetables (n = 80) (samples washed with tap water).

Sample Name	Scientific Name	As		Cd		Pb		Zn
Origin of the Samples		Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers
Fruiting Vegetables
Maximum levels (mg/kg)		0.5 a		0.05 a,b; 0.2 c,d		0.5 a; 0.2 b,c; 0.3 d		5.0 a
Tomato	Llycopersicon esculentum Mill.	388.86 ± 29.10	374.26 ± 42.10	16.48 ± 6.42	17.93 ± 4.59	66.81 ± 12.38	73.34 ± 15.72	3942.11 ± 431.55	4113.70 ± 125.40
Yellow Cherry Tomato	Lycopersicon esculentum Var. cerasiforme (sun gold hybrid)	254.53 ± 29.19	no samples	23.49 ± 3.79	no samples	51.34 ± 7.35	no samples	3563.84 ± 27.11	no samples
Red Cherry Tomato	Lycopersicon esculentum Mill	334.37 ± 50.77	317.90 ± 29.14	BLD	BLD	18.58 ± 4.67	BLD	3780.45 ± 113.00	4113.81 ± 122.88
Long Cucumber	Cucumis sativus	258.23 ± 46.76	240.03 ± 12.41	46.41 ± 2.53	48.63 ± 4.61	112.04 ± 22.24	59.82 ± 16.25	2847.48 ± 451.78	3039.74 ± 73.08
Kirby Cucumber		BLD	BLD	BLD	BLD	BLD	BLD	1358.74 ± 68.01	1853.70 ± 124.23
Red Beans	Phaseolus vulgaris	BLD	no samples	23.90 ± 7.99	no samples	46.15 ± 8.13	no samples	1735.33 ± 124.80	no samples
White Beans		163.04 ± 9.30	129.52 ± 5.91	18.76 ± 4.62	BLD	43.60 ± 15.94	26.81 ± 15.94	2821.95 ± 410.66	4061.19 ± 424.96
Zucchini	Cucurbita pepo	100.78 ± 20.41	BLD	14.18 ± 1.05	18.51 ± 5.72	30.20 ± 2.55	35.69 ± 8.58	2184.42 ± 168.16	1956.63 ± 72.16
Fruits
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.2 b; 0.2 c; 0.2 d		5.0 a
Raspberry	Rubus idaeus	BLD	BLD	BLD	BLD	BLD	BLD	1374.39 ± 50.70	1489.97 ± 152.52
Blueberry	Vaccinium corymbosum	BLD	no samples	BLD	no samples	BLD	no samples	2366.08 ± 210.54	no samples
Strawberry	Fragaria x ananassa	69.67 ± 26.76	73.95 ± 15.99	17.78 ± 3.50	BLD	10.78 ± 1.85	9.92 ± 4.38	1143.59 ± 168.11	1374.25 ± 71.85
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.1 b; 0.1c; 0.1 d		5.0 a
Watermelon	Citrullus lanatus	68.40 ± 24.06	43.13 ± 38.85	BLD	BLD	BLD	BLD	1102.96 ± 117.96	1305.56 ± 31.76
Bell pepper	Capsicum annuum L. var. grossum (Sendt)	BLD	BLD	BLD	BLD	BLD	BLD	1533.63 ± 95.21	1817.25 ± 40.87
Chestnut	Castanea sativa Mill.	27.47 ± 4.27	no samples	12.74 ± 1.30	no samples	BLD	no samples	3807.96 ± 217.90	no samples
Apples	Malus domestica Borkh.	BLD	BLD	BLD	BLD	BLD	BLD	946.53 ± 62.51	909.56 ± 72.67
Plums	Prunus domestica L.	116.92 ± 15.97	132.36 ± 21.03	BLD	BLD	BLD	BLD	596.93 ± 49.63	738.75 ± 132.90
Pear	Pyrus communis L.	BLD	BLD	15.19 ± 2.95	15.82 ± 3.97	78.13 ± 14.95	69.15 ± 23.18	440.15 ± 99.11	379.37 ± 63.19
Quince	Cydonia oblonga Mill.	BLD	BLD	BLD	BLD	BLD	BLD	3218.11 ± 218.26	2993.33 ± 124.35
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.1 b; 0.1 c; 0.2 d		5.0 a
Grapes	Vitis vinifera	81.85 ± 45.11	48.78 ± 6.94	14.78 ± 5.71	BLD	27.48 ± 15.75	18.32 ± 5.41	1362.93 ± 85.83	1288.26 ± 267.83
Leafy vegetables
Maximum levels (mg/kg)		-		0.20 a,b,c,d		0.5 a; 0.3 b; 0.3 c; 0.3 d		-
Cabbage	Brassica oleracea convar. capitata (L.) f. alba L.	19.78 ± 12.59	BLD	9.70 ± 1.31	BLD	25.41 ± 7.72	BLD	2814.32 ± 121.77	2885.18 ± 138.52
Tarragon	Artemisia dracunculus L.	BLD	no samples	BLD	no samples	BLD	no samples	4964.44 ± 280.40	no samples
Parsley	Petroselinum crispum convar. crispum (Denst.)	BLD	BLD	BLD	BLD	BLD	BLD	1366.95 ± 146.26	1698.12 ± 233.44
Lovage	Levisticumofficinale Koch.	no samples	BLD	no samples	BLD	no samples	BLD	no samples	428.81 ± 55.18
Dill	Anethum graveolens L.	7.60 ± 4.11	no samples	BLD	no samples	79.41 ± 13.01	no samples	994.47 ± 235.14	no samples
Lettuce	Lactuca sativa L. convar. capitata (L.)	1.44 ± 0.60	0.81 ± 0.51	46.88 ± 11.16	39.11 ± 4.54	155.07 ± 28.25	73.25 ± 17.70	1055.13 ± 61.07	3030.91 ± 777.65
Celery	Apium graveolens L. conv. rapaceum (Mill.)	BLD	BLD	BLD	BLD	BLD	BLD	741.26 ± 267.80	742.48 ± 168.77
Bulbs
Maximum levels (mg/kg)		0.5 a		0.1 a; 0.05 b; 0.1 c,d		0.5 a; 0.1 b,c,d;		15.0 a
Garlic	Allium sativum ssp. vulgare	207.88 ± 82.87	153.52 ± 31.21	0.14 ± 0.06	BLD	BLD	BLD	5139.25 ± 525.83	6178.18 ± 1468.35
Onion	Allium cepa	BLD	BLD	BLD	BLD	BLD	BLD	2737.88 ± 336.55	1163.25 ± 153.30
Root vegetables
Maximum levels (mg/kg)		0.5 a		0.1 a; 0.1 b,c,d		0.5 a; 0.1 b,c,d;		15.0 a
Potato	Solanum tuberosum	BLD	BLD	28.60 ± 12.84	BLD	65.41 ± 27.71	29.70 ± 77.3	6256.99 ± 2200.29	7640.07 ± 1095.27
Parsley	Petroselinum crispum convar. radicosum (Def.)	BLD	BLD	BLD	BLD	BLD	BLD	BLD	BLD
Carrot	Daucus carota L. conv. sativus	BLD	no samples	5.18 ± 1.69	no samples	14.56 ± 5.69	no samples	1039.56 ± 174.48	no samples

^a Maximum permissible limit according to the Romanian Ministry of Agriculture Food and Forestry Order No. 293/640/2001-1/2002 on the security and quality conditions of fresh fruit and vegetables for human consumption (M.Of 173/13 March 2002); ^b Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. ^c Maximum permissible limit according to Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (FAO-WHO 2011); ^d Maximum permissible limit according to Romanian Health Minister Order no. 1201/106/2003 the approval of food contaminants regulation (M.Of. 142/17 February 2004). BLD = below the detection limit (LoQ); LoQ for As: 0.743 µg/L; LoQ for Cd: 0.069 µg/L, LoQ for Pb: 0.231 µg/L, LoQ for Zn 1.203 µg/L; FW = fresh weight; average value ± standard deviation (SD).

). In the case of fruits, leafy vegetables, and bulbus, As recorded an average value of 33.13 µg/kg FW, 2.69 µg/kg FW, and 90.35 µg/kg FW, respectively, while rooting vegetables recorded values lower then LoQ. In this investigation, the maximum concentration of As was observed in tomato (381.56 µg/kg FW), yellow cherry tomato (254.53 µg/kg FW), red cherry tomato (326.14 µg/kg FW), and long cumber (249.13 µg/kg FW). White beans (146.29 µg/kg FW), zucchini (100.78 µg/kg FW), plums (147.14 µg/kg FW), and garlic (180.70 µg/kg FW) also recorded high values of As.

Lower concentrations of As were identified in strawberry, watermelon, chestnut, grapes, cabbage, dill, lettuce, and celery, with values ranging between 1.44 µg/kg FW and 81.85 µg/kg FW. In the case of kirby cucumber, red beans, raspberry, blueberry, bell pepper, apples, pear, quince, tarragon, parsley, celery, onion, potato, parsley, and carrot, the values obtained for these samples were below the LoQ. The concentrations of As in fruit and vegetable samples decreased in the order of tomato > long cucumber > garlic > white beans > zucchini > grapes > watermelon > strawberry > chestnut > cabbage > dill > lettuce > kirby cucumber > red beans > raspberry > blueberry > bell pepper > apples > pear > quince > tarragon > parsley > celery > onion > potato > parsley > carrot. According to Codex Alimentarius, the mean As concentration in all fruits and vegetables should be lower than 0.1 mg/kg [33]. It is generally observed that fruiting vegetables (338.86 µg/kg FW), bulbus (207.88 µg/kg FW), and fruits (132.36 µg/kg FW), have higher concentrations of As compared to leafy vegetables (19.78 µg/kg FW) and root vegetables (<LoQ).

The origins of the fruits and vegetables had a significant influence in terms of As accumulation. The highest values were recorded in samples collected from the vegetable market as compared to amateur farms in the case of fruiting vegetables (187.48 µg/kg FW), leafy vegetables (4.80 µg/kg FW), and bulbus (103.94 µg/kg FW). In the case of fruits (33.12 µg/kg FW—vegetable market; 33.14 µg/kg FW—amateur farmers) and root vegetables (< LoQ in both cases), no difference was noted. Samples collected from the vegetable market (85.08 µg/kg FW) recorded up to 35% more As compared to amateur farmers (63.09 µg/kg FW). The obtained results are below the maximum permitted limit set by national law (0.5 mg/kg), but exceed the recommended limit in Codex Alimentarius (0.1 mg/kg).

The results obtained for As are comparable to those obtained by Antoine et al. (2017) [34] (0.001–0.012 mg/kg FW cabbage, carrot, and tomato samples from Jamaica), Resmije et al. (2019) [35] (Undetectable [ND]–0.009 mg/kg, apple samples from Kosovo), Marín et al. (2018) [36] (0.0188–0.0101 mg/kg, fruit and vegetable samples from Spain), Shutian et al. (2019) [37] (0.045 mg/kg chestnut samples from China), and Ciocarlan et al. (2021) [38] (0.142 mg/kg lovage samples from Moldavia). The Romanian scientific literature is very poor regarding data for heavy metal concentrations from fruits and vegetables grown in Romania; comparable sources are not available.

3.1.2. Cadmium

Research has shown the obvious carcinogenic effects of Cd on humans [30], as it is largely bound to metallothionein in the body, and this complex is transported to various tissues and organs [39]. The human body does not have a natural mechanism for removing Cd, so these heavy metal residues are deposited in the tissues and can affect organs such as the liver, pancreas, and lungs [40]. Cd can also reduce bone mineral density, leading to skeletal damage (fractures, osteoporosis, and osteomalacia) [41]. Exposure to a high concentration of Cd can lead to cardiovascular disease and high blood pressure [42], reduce endothelial cell function, and cause cell death, aggregation of smooth muscle cells, vascular inflammation, the release of cytokines, and angiogenesis [43]. The cellular disturbances result in hypertension and ischemic heart disease [30].

Cd concentrations in fruits and vegetables range from LoQ (LoQ for Cd: 0.069 µg/L) to 48.63 µg/kg FW, with an average concentration of 8.04 µg/kg FW (Table 1). In the present study, fruiting vegetables (16.31 µg/kg FW) record the highest concentrations, followed by leafy vegetables (8.70 µg/kg FW), root vegetables (6.75 µg/kg FW), and fruits (3.82 µg/kg FW). The lowest Cd concentration was recorded in bulbus (0.03 µg/kg FW). The highest concentrations of Cd were observed in long cucumber (47.52 µg/kg FW), lettuce (43.00 µg/kg FW), potato (28.60 µg/kg FW), red beans (23.90 µg/kg FW), yellow cherry tomato (23.49 µg/kg FW), white beans (18.76 µg/kg FW), and tomato (17.21 µg/kg FW). The lowest concentrations of Cd were identified in raspberry, watermelon, chestnut, apples, plums, quince, cabbage, tarragon, parsley, lovage, dill, celery, garlic, and carrot, with values between 0.14 µg/kg FW and 15.19 µg/kg FW. The concentrations of Cd in fruit and vegetable samples decreased in the order of lettuce > long cucumber > potato > read beans > yellow tomato > white beans > strawberry > tomato > pear > grapes > zucchini > chestnut > cabbage > carrot > garlic. In the case of red cherry tomato, raspberry, bell pepper, apples, plums, quince, tarragon, parsley, dill, celery, onion, and parsley, the values obtained for these samples were below LoQ.

The origin of the samples had a significant influence. Significant influence was observed in the case of fruiting vegetables (17.90 µg/kg FW), fruits (5.50 µg/kg FW), leafy vegetables (9.43 µg/kg FW), bulbus (0.07 µg/kg FW), and root vegetables (11.26 µg/kg FW); higher values were recorded in samples collected from the vegetable market. Additionally, in samples collected from amateur farmers, there were significant differences between the analyzed fruit and vegetable classes; fruiting vegetables (14.18 µg/kg FW), fruits (1.76 µg/kg FW), leafy vegetables (7.82 µg/kg FW), bulbus, and root vegetables (< LoQ in both cases). Samples collected from the vegetable market (9.81 µg/kg FW) recorded up to 68% more Cd (average value) compared to amateur farmers (5.83 µg/kg FW). The obtained results were below the maximum permitted limit set by national law (0.05 mg/kg) and FAO-WHO (0.2 mg/kg).

The results obtained for Cd were comparable to those obtained by Rusin et al. (2021) [44] (0.001–0.131 mg/kg fruit samples from Poland), Bagdatlioglu et al. (2010) [45] (ND–0.024 µg/g vegetable samples from Turkey), Marín et al. (2018) [36] (ND–0.0088 mg/kg vegetable and fruit samples from Spain), Shutian et al. (2019) [37] (0.043 mg/kg chestnut samples from China), Zeiner et al. (2018) [46] (Cd < 0.028 mg/kg d.w.), and Ferrante et al. (2013) [47] (Cd < 0.004–0.71 µg/g fruit and vegetable samples from Italy). In a study by Antić-Mladevović et al. (2009) [48], Cd levels in raspberry and blueberry samples from Montenegro (0.59–0.64 mg/kg DW) were significantly higher than those presented in this study. In previous studies, the Cd concentration found in fruits and vegetables from Romania ranged from ND to 0.55 mg/kg in research presented by Popa et al. (2010) [49] (ND dill, parsley, lovage and celery collected from, Timiș, Romania), Manea et al. (2020) [50] (0.01–0.03 mg/kg from tomatoes, potatoes, apples, apricots, peaches, and pears, whereas for sweet cherries, sours, plums, and grapes samples from Romania), and Roba et al. (2016) [16] (ND–0.55 mg/kg fresh, 15 vegetable species and eight fruit species collected from the inhabitants’ gardens from five urban areas: Baia Mare, Ferneziu, Grivița, Valea Roșie, and Valea Borcutului; and four rural areas: Tăuții de Sus, Satu Nou de Sus, Recea, and Lăpușel during June and August 2014).

3.1.3. Lead

Pb can damage human cells by reducing antioxidants and producing free radicals [51]. This has the effect of increasing the radical oxygen species levels that induce carcinogenesis by damaging existing DNA and causing delayed replication of DNA and clastogenicity [52]. Pb can induce apoptosis and toxicity in human cancer cells, which have multiple consequences, from oxidative stresses to the death of human subjects [53]. Long-term exposure to Pb can cause memory deterioration, prolonged reaction times, and reduced ability to understand [30]. Exposure of children to a high concentration of Pb leads to behavioral disorders related to concentration or learning processes [3].

Amongst the fruiting vegetables (35.35 µg/kg FW) and leafy vegetables (30.29 µg/kg FW), Pb content was found to be the highest in lettuce (114.16 µg/kg FW) and long cucumber (85.93 µg/kg FW) (Table 1). The Pb concentrations in fruit and vegetable range from < LoQ (LoQ for Pb: 0.231 µg/L) to 155.07 µg/kg FW, with an average concentration of 22.61 µg/kg FW. High concentrations of Pb were recorded in tomato (70.08 µg/kg FW), yellow cherry tomato (51.34 µg/kg FW), pear (73.64 µg/kg FW), and dill (79.41 µg/kg FW). The lowest concentrations of Pb were identified in red cherry tomato, kirby cucumber, zucchini, raspberry, blueberry, strawberry, watermelon, bell pepper, chestnut, apples, plums, quince, grapes, cabbage, tarragon, parsley, lovage, celery, garlic, onion, parsley, and carrot, with values ranging between 9.92 µg/kg FW and 66.81 µg/kg FW. The concentrations of Pb in fruit and vegetable samples decreased in the order of lettuce > long > cucumber > dill > pear > tomato > potato > yellow tomato > red beans > white beans > zucchini > grapes > cabbage > red tomato carrot > strawberry. In the case of kirby, cucumber, raspberry, blueberry, watermelon, bell pepper, chestnut, apples, plums, quince, tarragon, parsley, celery, garlic, onion, and parsley, the values obtained for these samples were below the LoQ. The obtained results were below the maximum permitted limit set by national law (0.5 mg/kg), but exceeded the recommended limit in Codex Alimentarius, according to Codex; the mean Pb concentration in all fruits and vegetables should be lower than 0.1 mg/kg [33].

In terms of Pb accumulation, the origins of the samples had a significant influence in the case of leafy vegetables (43.32 µg/kg FW) and root vegetables (26.66 µg/kg FW); higher values were recorded in samples collected from the vegetable market. Fruit and vegetable samples collected from amateur farmers recorded higher values for fruiting vegetables (32.61 µg/kg FW) and fruits (10.82 µg/kg FW). For bulbus samples, no differences were identified between those from the vegetable market and those from amateur farmers in terms of Pb concentration (<LoQ in both cases). Samples collected from the vegetable market (27.50 µg/kg FW) recorded up to 67% more Pb (average value) compared to amateur farmers (16.50 µg/kg FW).

The results obtained for Pb are comparable to those obtained by Radwan et al. (2006) [18] (0.08–0.87 mg/kg dry wt. fruit samples from Egypt), Rusin et al. (2021) [44] (0.009–0.259 mg/kg fruit samples from Poland), Resmije et al. (2019) [35] (0.31–2.17 mg/kg, apple samples from Kosovo), Bagdatlioglu et al. (2010) [45] (0.004–0.249 µg/g vegetable samples from Turkey), Marín et al. (2018) [36] (0.0028–0.0129 mg/kg vegetable and fruit samples from Spain), Shutian et al. (2019) [37] (0.041 mg/kg chestnut samples from China), Demirezen et al. (2006) [54] (30–10.7 µg/g vegetable samples from Turkey), Zeiner et al. (2018) [46] (0.601–3.34 mg/kg d.w.), and Ferrante et al. (2013) [47] (Pb < 0.004–0.50 µg/g fruit and vegetable samples from Italy). In the case of the results presented by Antić-Mladevović et al. (2009) [48] (6.0–10.5 mg/kg DW, raspberry and blueberry samples from Montenegro), these were significantly higher than in the present study. In previous studies, the Pb concentration found in fruits and vegetables from Romania ranged from ND to 0.139 ppm in research presented by Popa et al. (2010) [49] (vegetable samples), 0.03–0.28 mg/kg Manea et al. (2020) [50] (vegetable and fruit samples). Pb levels in the study by Roba et al. (2016) (ND–6.6 mg/kg) were significantly higher than in the present study [16].

3.1.4. Zinc

Zn is relatively harmless as compared to several other few metals ions with similar chemical properties. Only exposure to high doses of Zn has potential toxic effects, which means that acute Zn poisoning is a rare event [55]. Normally, the human body contains 2–3 g of Zn, mainly (90%) in the muscles and bones; other organs containing estimable levels of Zn are the lungs, liver, gastrointestinal tract, kidney, heart, and pancreas [55]. Based on research, it was concluded that Zn is not generally considered to be a causative metal for cancer development; on the contrary, displacement of binding structures, e.g., finger structure, in DNA repair enzymes may even be a major mechanism for the carcinogenicity of other metals, such as Cd, Co, Ni, and As [56]. In addition to the systemic toxic effects of Zn, this metal is also involved in the regulation of life and death decisions on the cellular level (e.g., many studies indicate that Zn acts as a neuromodulator) [55].

Zinc concentration varied in the range of < LoQ (LoQ for Zn: 1.203 µg/L) and 7640.07 µg/kg FW, with an average concentration of 2268.22 µg/kg FW (Table 1). Bulbus (3804.64 µg/kg FW) recorded the highest concentrations, followed by root vegetables (2987.32 µg/kg FW) and fruiting vegetables (2955.93 µg/kg FW). At the opposite pole, the lowest Zn concentrations were recorded in leafy vegetables (1886.92 µg/kg FW) and fruits (1509.48 µg/kg FW). The maximum concentrations of Zn were observed in potato (7098.53 µg/kg FW), garlic (5658.72 µg/kg FW), tarragon (4964.44 µg/kg FW), tomato (4027.91 µg/kg FW), red cherry tomato (3947.13 µg/kg FW), and chestnut (3807.96 µg/kg FW). The lowest concentrations of Zn were identified in onion, carrot, bell pepper, apples, plums, grapes, cabbage, parsley, dill, lettuce, celery, watermelon, strawberry, blueberry, raspberry, zucchini, white beans, red beans, kirby cucumber, and long cucumber, with values between 440.15 µg/kg FW and 3218.11 µg/kg FW. The concentrations of Zn in fruit and vegetable samples decreased in the order of potato > garlic > tarragon > tomato > chestnut > red cherry tomato >yellow cherry tomato > quince > long cucumber > kirby cucumber > white beans > cabbage > onion > blueberry > zucchini > bell pepper > red beans > raspberry > parsley > grapes > strawberry > watermelon > lettuce > carrot > dill > apples > celery > plums > pear > parsley.

A significant influence of the origin of the fruits and vegetables on Zn accumulation was observed in the case of fruiting vegetables (3191.46 µg/kg FW) and root vegetables (3820.03 µg/kg FW) collected from amateur farmers, with Zn higher in these than in samples collected from the vegetable market (fruiting vegetables 2779.29 µg/kg FW, root vegetables 2432.18 µg/kg FW). Conversely, fruits (1626.66 µg/kg FW), leafy vegetables (1989.43 µg/kg FW), and bulbus (3938.56 µg/kg FW) recorded the highest levels of Zn in samples collected from the vegetable market. Samples collected from the amateur farmers (2301.92 µg/kg FW) recorded up to 3% more Zn (average value) compared to the vegetable market (2241.26 µg/kg FW). The obtained results are below the maximum permitted limit set by national law.

The results obtained for Zn are comparable to those obtained by Elbagermi et al. (2012) [17] (0.042–16.83 mg/kg fruit and vegetable samples from Libya), Radwan et al. (2006) [18] (1.36–20.9 mg/kg dry wt. fruit samples from Egypt), Ali et al. (2012) [57] (14.53 µg/g dry weight fruit and vegetable samples from Saudi Arabia), Resmije et al. (2019) [35] (0.31–2.03 mg/kg, apple samples from Kosovo), Bagdatlioglu et al. (2010) [45] (0.41–10.81 µg/g vegetable samples from Turkey), Santos et al. (2004) [58] (0.20–45.00 mg/kg vegetable samples from Brazil), Demirezen et al. (2006) [54] (3.56–259.2 µg/g vegetable samples from Turkey), Hossain et al. (2010) [59] (20 mg/kg tomato samples from Australia), Grembecka et al. (2013) [20] (0.03–0.44 mg/100 g wet weight fresh fruit samples from Poland, Italy, and Spain), Ferrante et al. (2013) [47] (Zn < 0.002–21.80 µg/g fruit and vegetable samples from Italy), and Michenaud-Rague et al. (2012) [60] (1.4–13.2 µg/g fruit samples from USA), Corregidor et al. (2020) [61] (15–27 µg/g chestnut samples from Portugal). In studies by Ciocarlan et al. (2021) [38] (47 mg/kg lovage samples from Moldavia), Popa et al. (2010) [49] (5.15–12.35 ppm vegetable samples from Romania), Manea et al. (2020) [50] (0.93–9.67 mg/kg FW vegetable and fruit samples from Romania), and Roba et al. (2016) [16] (0.6–45.7 fresh weight basis fruit and vegetable samples from Romania), Zn concentrations were significantly higher than in the present study.

3.2. Reduce Heavy Metals in Fruits and Vegetables by Soaking with 5% Vinegar

To reduce the heavy metal concentrations in fruit and vegetable samples, the following samples were washed with 5% vinegar: fruiting vegetables (tomato, yellow cherry tomato, red cherry tomato, long cucumber, zucchini), fruits (strawberry, pear, grapes), leafy vegetables (cabbage, lettuce), bulbus (garlic), and root vegetables (carrot) (

Table 2. Mean and standard deviation for heavy metal concentrations (µg/kg FW) in fruiting vegetables, fruits, leafy vegetables, bulbs, and root vegetables (n = 80) (samples washed with vinegar—5% acetic acid).

Sample Name	Scientific Name	As		Cd		Pb		Zn
Origin of the Samples		Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers
Fruiting vegetables
Maximum levels (mg/kg)		0.5 a		0.05 a,b; 0.2 c,d		0.5 a; 0.2 b,c; 0.3 d		5.0 a
Tomato	Llycopersicon esculentum Mill.	202.19 ± 19.22	175.40 ± 19.06	12.20 ± 2.23	7.00 ± 1.91	53.96 ± 9.52	55.45 ± 5.02	3328.74 ± 212.85	3937.54 ± 80.91
Yellow Cherry Tomato	Lycopersicon esculentum Var. cerasiforme (sun gold hybrid)	188.89 ± 11.96	no samples	17.27 ± 0.97	no samples	37.73 ± 2.92	no samples	3251.94 ± 49.52	no samples
Red Cherry Tomato	Lycopersicon esculentum Mill	243.73 ± 9.60	231.29 ± 2.39	BLD	BLD	14.24 ± 3.75	BLD	3753.05 ± 47.37	4032.43 ± 60.30
Long Cucumber	Cucumis sativus	220.67 ± 18.93	212.70 ± 5.34	41.23 ± 0.92	46.21 ± 2.22	76.19 ± 8.07	45.26 ± 5.14	2856.76 ± 481.35	3012.07 ± 40.88
Zucchini	Cucurbita pepo	91.35 ± 11.41	BLD	BLD	BLD	22.98 ± 0.94	28.61 ± 14.47	1996.25 ± 14.47	1943.09 ± 65.85
Fruits
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.2 b; 0.2 c; 0.2 d		5.0 a
Strawberry	Fragaria x ananassa	52.79 ± 12.89	66.44 ± 16.86	BLD	BLD	BLD	BLD	1119.83 ± 120.00	1354.20 ± 33.55
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.1 b; 0.1 c; 0.1 d		5.0 a
Pear	Pyrus communis L.	BLD	BLD	14.79 ± 1.33	16.78 ± 0.40	74.94 ± 4.37	63.97 ± 19.74	437.57 ± 98.91	374.30 ± 67.95
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.1 b; 0.1 c; 0.2 d		5.0 a
Grapes	Vitis vinifera	76.63 ± 14.46	48.71 ± 5.38	14.66 ± 2.35	BLD	24.44 ± 14.31	16.98 ± 4.96	1354.49 ± 97.81	1237.83 ± 188.78
Leafy vegetables
Maximum levels (mg/kg)		-		0.20 a,b,c,d		0.5 a; 0.3 b; 0.3 c; 0.3 d		-
Cabbage	Brassicaoleracea convar. capitata (L.) f. alba L.	BLD	BLD	BLD	BLD	BLD	BLD	2695.65 ± 217.47	2858.42 ± 41.64
Lettuce	Lactuca sativa L. convar. capitata (L.)	BLD	BLD	43.67 ± 1.81	33.78 ± 6.62	108.79 ± 5.60	71.49 ± 3.06	1035.12 ± 22.58	2949.49 ± 462.23
Bulbs
Maximum levels (mg/kg)		0.5 a		0.1 a; 0.05 b; 0.1 c,d		0.5 a; 0.1 b,c,d;		15.0 a
Garlic	Allium sativum ssp. vulgare	191.13 ± 54.07	151.87 ± 10.66	BLD	BLD	BLD	BLD	5003.11 ± 157.42	5293.34 ± 367.19
Root vegetables
Maximum levels (mg/kg)		0.5 a		0.1 a; 0.1 b,c,d		0.5 a; 0.1 b,c,d;		15.0 a
Potato	Solanum tuberosum	BLD	BLD	27.97 ± 9.42	BLD	63.47 ± 1.48	13.22 ± 1.82	6134.38 ± 476.38	7084.80 ± 727.80
Carrot	Daucus carota L. conv. sativus	BLD	no samples	BLD	no samples	BLD	no samples	1022.26 ± 91.29	no samples

^a Maximum permissible limit according to the Romanian Ministry of Agriculture Food and Forestry Order No. 293/640/2001-1/2002 on the security and quality conditions for fresh fruit and vegetables for human consumption (M.Of 173/13 March 2002); ^b Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. ^c Maximum permissible limit according to the Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (FAO-WHO 2011); ^d Maximum permissible limit according to Romanian Health Minister Order no. 1201/106/2003 the approval of food contaminants regulation (M.Of. 142/17 February 2004). BLD = below the detection limit (LoQ); LoQ for As: 0.743 µg/L; LoQ for Cd: 0.069 µg/L, LoQ for Pb: 0.231 µg/L, LoQ for Zn 1.203 µg/L; FW = fresh weight. Average value ± standard deviation (SD).

). The selection of these samples was made by the results obtained from analyzed samples washed with tap water, so samples that showed a low concentration of heavy metals, or those that were below the detection limit were excluded. The washing time of the samples with vinegar varied between 5 min and 10 min at 30 °C depending on the size and number of the samples. The washing time was chosen so that it simulated the real conditions of the consumers of fruits and vegetables, and the vinegar used was vinegar (5% acetic acid) obtained from apples and available in any grocery store.

After the fruit and vegetable samples had been washed with 5% vinegar for 3–5 min, a decrease in heavy metal concentrations was observed compared to the initial analyses. A considerable reduction in heavy metals was detected in the case of fruiting vegetables (tomato, yellow cherry tomato, red cherry tomato, and long cucumber), leafy vegetables (lettuce), fruits (strawberry, pear, grapes), and root vegetables (potato). Bulbus (garlic) showed a reduction in As and Zn concentrations. The results revealed that heavy metals in washed tomato (tomato, yellow cherry tomato, red cherry tomato) and long cucumber were decreased, with values between 30% and 93%.

Reductions in heavy metal concentrations were recorded for As, Cd, and Pb, the highest values being observed in the case of As (93% in tomato), followed by Cd (79% in tomato) and Pb (42% in long cucumber). The same trend was observed in the case of zucchini, strawberry, grapes, lettuce, and potato, which also showed a significant reduction in heavy metals compared to the initial analyses. There were also cases in which washing with vinegar had no significant effect on the concentrations of heavy metals; in particular, pear (2% for Cd, 6% for Pb), grapes (1% for Pb), garlic (5% for As), and potato (2% for Cd). Zinc concentration did not seem to be influenced by this operation; a slight reduction in Zn was only observed in the case of tomato (11%), yellow cherry tomato (10%), and garlic (10%), while red cherry tomato, long cucumber, zucchini, strawberry, pear, grapes, cabbage, lettuce, potato, and carrot showed a reduction in the concentration of Zn of between 5% and 1%.

As concentrations varied in the range of < LoQ (LoQ for As: 0.743 µg/L) to 243.73 µg/kg FW with an average concentration of 90.49 µg/kg FW (Table 2). Fruiting vegetables (176.03 µg/kg FW), bulbus (171.50 µg/kg FW), and fruits (40.76 µg/kg FW) recorded the highest As concentrations. Conversely, the lowest As concentrations were recorded in leafy vegetables and root vegetables. The highest concentrations of As were observed in red cherry tomato (237.49 µg/kg FW), long cucumber (216.69 µg/kg FW), tomato (188.80 µg/kg FW), garlic (171.00 µg/kg FW), and yellow cherry tomato (188.89 µg/kg FW). The lowest concentrations of As were identified in zucchini, grapes, strawberry, pear, cabbage, lettuce, potato, and carrot, with values ranging between 48.71 µg/kg FW and 91.35 µg/kg FW.

The concentrations of As in fruit and vegetable samples decreased in the order of red cherry tomato > long cucumber > tomato > garlic > yellow cherry tomato > zucchini > grapes > strawberry > pear > cabbage > lettuce > potato > carrot. Concerning the origins of the fruits and vegetables, samples collected from the vegetable market (98.88 µg/kg FW) recorded up to 23% more As (average value) compared to the those from amateur farmers (80.58 µg/kg FW). The obtained results were below the maximum permitted limit set by national law (0.5 mg/kg), but exceeded the recommended limit in Codex Alimentarius (0.1 mg/kg).

Regarding the Cd and Pb concentrations from fruits and vegetables washed with 5% vinegar, the average values were 32.15 µg/kg FW for Pb and 11.48 µg/kg FW for Cd. High values were recorded for leafy vegetables (45.07 µg/kg FW—Pb, 43.67 µg/kg FW—Cd), fruiting vegetables (76.19 µg/kg FW—Pb, 46.21 µg/kg FW—Cd), and fruits (74.94 µg/kg FW—Pb, 16.78 µg/kg FW—Cd). Cd followed the same trend as observed for As; the highest concentration of Cd was recorded in long cucumber (43.72 µg/kg FW), and the lowest concentrations were recorded in tomato, red cherry tomato, zucchini, strawberry, cabbage, garlic, and carrot. The concentrations of Cd in fruit and vegetable samples decreased in the order of lettuce > long cucumber > potato > yellow cherry tomato > pear > grapes > tomato > red cherry tomato > zucchini > strawberry > cabbage > garlic > carrot. Contrary to the trend recorded in the As and Cd distribution, the highest concentrations of Pb were recorded in lettuce (90.14 µg/kg FW) and long cucumber (60.73 µg/kg FW). The concentrations of Pb in fruit and vegetable samples decreased in the order of lettuce > long cucumber > pear > potato > tomato > yellow cherry tomato > grapes > zucchini > red cherry tomato > strawberry > cabbage > garlic > carrot. As expected, the samples of fruits and vegetables that came from the vegetable and fruit market recorded up to 40% and 37% more Cd and Pb, respectively (13.21 µg/kg FW—Cd and 36.67 µg/kg FW), compared to those from the amateur farmers (9.43 µg/kg FW—Cd and 26.81 µg/kg FW). The obtained results were below the maximum permitted limit set by national law (0.05 mg/kg—Cd, 0.5 mg/kg—Pb) and FAO-WHO (0.2 mg/kg—Cd). The exception to this rule was Pb concentration in lettuce samples (108.79 µg/kg FW from the vegetable and fruit market) which slightly exceeded the recommended limit in Codex Alimentarius (0.1 mg/kg).

Based on the present research, it can be concluded that Zn concentrations in fruits and vegetables were less influenced by the washing of the samples with 5% vinegar than those of other metals. Reductions in Zn concentrations were noticed in the analyzed samples, but were low, and did not warrant the recommendation of this washing procedure. Zn concentration varied in the range of 374.30 to 7084.80 µg/kg FW, with an average concentration of 2836.13 µg/kg FW. Bulbus (5148.23 µg/kg FW), root vegetables (4747.15 µg/kg FW), and fruiting vegetables (3123.54 µg/kg FW) recorded the highest Zn concentrations, while the lowest Zn concentration was recorded in leafy vegetables (2384.78 µg/kg FW) and fruits (979.70 µg/kg FW). The maximum concentration of Zn was observed in potato (6134.38 µg/kg FW—samples from vegetables and fruit market, and 7084.80 µg/kg FW—samples from amateur farmers) and garlic (5003.11 µg/kg FW—samples from vegetables and fruit market, and 5293.34 µg/kg FW—samples from amateur farmers). The lowest concentration of Zn was identified in pear (405.94 µg/kg FW) and carrot (1022.26 µg/kg FW). The concentration of Zn in fruit and vegetable samples decreased in the order of potato > garlic > red cherry tomato > tomato > yellow cherry tomato > long cucumber > cabbage > zucchini > grapes > strawberry > lettuce > carrot > pear. Concerning the origins of the fruits and vegetables (vegetable market or amateur farmers), samples collected from the amateur farmers (3098.00 µg/kg FW) recorded up to 18% more Zn (average value) compared to the vegetable market (2614.55 µg/kg FW). The obtained results were below the maximum permitted limit set by national law (5 and 15 mg/kg).

Based on the studies and on the statistical analysis performed, washing with 5% vinegar can be recommended for fruit and vegetables, regardless of their origin (vegetable and fruit market or amateur farmers); this operation considerably reduces the concentrations of As, Cd, and Pb. Results showed a reduction in As of up to 35% (from 121.94 µg/kg FW to 90.49 µg/kg FW), a reduction in Cd of 37% (from 15.78 µg/kg FW to 11.48 µg/kg FW), and a reduction in Pb of 33% (from 42.71 µg/kg FW to 32.15 µg/kg FW) in samples washed with acetic acid compared to those washed with water. Regarding Zn concentrations, the results showed a reduction of up to 5% in samples washed with acetic acid (2836.13 µg/kg FW) compared to those washed only with water (2983.51 µg/kg FW).

Results published in previous studies for As [34,35,36,37,38], Cd [36,37,44,45,46,47], Pb [18,35,36,37,44,45,46,47,48,54], and Zn [17,18,34,35,45,47,54,57,58,59,60,61] are comparable to the findings from the present study. Our results are also in line with previous research carried out on samples of fruits and vegetables from Romania [16,49,50] and Moldavia [38].

3.3. Reduce Heavy Metals in Fruits and Vegetables by Soaking with 10% Vinegar

Similarly to the samples washed with 5% vinegar, samples washed with 10% vinegar showed a decrease in heavy metal concentrations as compared to the initial analyses. A considerable reduction in heavy metals can be observed in the case of fruiting vegetables (tomato, yellow cherry tomato, red cherry tomato, long cucumber, and zucchini), fruits (strawberry, grapes), and leafy vegetables (lettuce, garlic). A considerable reduction in heavy metals was also identified in those samples where 5% vinegar had not resulted in any significant decrease. Heavy metals in washed tomato (tomato, yellow cherry tomato, red cherry tomato) and long cucumber were decreased, with values between 10% and 100%.

Reductions in heavy metal concentrations were recorded for As, Cd, and Pb, the highest values being observed for Pb (100% red cherry tomato), Cd (93% in tomato), and As (91% in tomato). The same trend was observed in the case of yellow cherry tomato, long cucumber, zucchini, strawberry, grapes, lettuce, and garlic, which also showed a significant reduction in heavy metals compared to the initial analyses. There were also cases in which washing with 10% vinegar had no significant effect on the concentration of heavy metals; in particular, pear (1% for Cd) and potato (5% for Pb). Zn concentration did not seem to be influenced by this operation. A slight reduction in Zn level was observed for garlic (20%), potato (19%), tomato (17%), cabbage (13%), grapes (12%), carrot (10%), long cucumber (8%), yellow cherry tomato (7%), pear (6%), strawberry (4%), red cherry tomato (3%), and zucchini (1%). An exception was the lettuce, which showed a reduction of up to 32% from the initial concentration, while only a 3% reduction was detected after washing with 5% vinegar.

Regarding the As and Cd concentrations from fruits and vegetables washed with 10% vinegar, values varied widely in the range of < LoQ (LoQ for As: 0.743 µg/L; LoQ for Cd: 0.069 µg/L) to 223.28 µg/kg FW for As and 41.81 µg/kg FW for Cd, with an average concentration of 84.16 µg/kg FW—As and 9.55 µg/kg FW—Cd. Fruiting vegetables (137.66 µg/kg FW), bulbus (148.46 µg/kg FW), and fruits (35.55 µg/kg FW) recorded the highest As concentrations, and the lowest As concentrations were recorded in leafy vegetables and root vegetables (< LoQ). While leafy vegetables (17.34 µg/kg FW), fruiting vegetables (12.95 µg/kg FW), and fruits (7.23 µg/kg FW) recorded the highest Cd concentrations, the lowest Cd concentrations were recorded in bulbus and root vegetables (< LoQ). The maximum concentrations of As and Cd were observed in red cherry tomato cherry (214.97 µg As/kg FW) and long cucumber (40.90 µg Cd/kg FW), followed by tomato (199.25 µg As/kg FW) and lettuce (34.68 µg As/kg FW). The lowest concentrations of As and Cd were identified in strawberry (44.66 µg As/kg FW) and tomato (8.90 µg As/kg FW). The concentrations of As in fruit and vegetable samples decreased in the order red cherry tomato > tomato > long cucumber > yellow cherry tomato > garlic > zucchini > grapes > strawberry > pear > cabbage > lettuce > potato > carrot. Concerning the origins of the fruits and vegetables (vegetable market or amateur farmers), samples collected from the vegetable market (93.05 µg As/kg FW and 10.05 µg Cd/kg FW) recorded up to 26% more As and up to 12% more Cd (average value) compared to those from the amateur farmers (73.65 µg As/kg FW and (8.97 µg Cd/kg FW). The concentrations of Cd in fruit and vegetable samples decreased in the order of long cucumber > lettuce > yellow cherry tomato > pear > grapes > tomato > red cherry tomato > zucchini > strawberry > cabbage > garlic > potato > carrot. By reporting the results to the maximum allowed limits established by law, the obtained results were below the maximum permitted limit (0.5 mg/kg—As) and (0.05 mg/kg—Cd, 0.5 mg/kg—Cd) and FAO-WHO (0.2 mg/kg—Cd), with the exception of As concentration, which exceeded the recommended limit in Codex Alimentarius (0.1 mg/kg) (

Table 3. Mean and standard deviation for heavy metal concentrations (µg/kg FW) in fruiting vegetables, fruits, leafy vegetables, bulbs, and root vegetables (n = 80) (samples washed with vinegar—10% acetic acid).

Sample Name	Scientific Name	As		Cd		Pb		Zn
Origin of the Samples		Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers	Vegetable and Fruit Market	Amateur Farmers
Fruiting vegetables
Maximum levels (mg/kg)		0.5 a		0.05 a,b; 0.2 c,d		0.5 a; 0.2 b,c; 0.3 d		5.0 a
Tomato	Llycopersicon esculentum Mill.	217.02 ± 16.92	181.48 ± 9.20	9.92 ± 0.28	7.88 ± 0.48	53.54 ± 3.19	47.90.90	3249.31 ± 149.70	3638.93 ± 157.78
Yellow Cherry Tomato	Lycopersicon esculentum Var. cerasiforme (sun gold hybrid)	184.12 ± 8.31	no samples	16.93 ± 1.32	no samples	32.95 ± 1.79	no samples	3319.00 ± 86.28	no samples
Red Cherry Tomato	Lycopersicon esculentum Mill	223.28 ± 15.74	206.65 ± 5.69	BLD	BLD	8.55 ± 1.05	BLD	3756.90 ± 65.57	3917.89 ± 94.31
Long Cucumber	Cucumis sativus	212.82 ± 4.09	200.74 ± 2.02	39.99 ± 1.50	41.81 ± 4.79	102.45 ± 6.74	53.33 ± 14.95	2485.62 ± 122.53	2951.89 ± 62.65
Zucchini	Cucurbita pepo	82.87 ± 6.82	BLD	BLD	BLD	20.60 ± 1.32	23.42 ± 7.58	2160.86 ± 53.14	1923.14 ± 29.58
Fruits
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.2 b; 0.2 c; 0.2 d		5.0 a
Strawberry	Fragaria x ananassa	44.16 ± 2.63	45.16 ± 5.81	BLD	BLD	BLD	BLD	1059.94 ± 26.37	1361.67 ± 19.76
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.1 b; 0.1 c; 0.1 d		5.0 a
Pear	Pyrus communis L.	BLD	BLD	14.94 ± 1.46	15.79 ± 1.41	69.03 ± 1.37	64.36 ± 19.48	393.68 ± 52.57	377.08 ± 54.10
Maximum levels (mg/kg)		0.5 a		0.05 a,b,c,d		0.5 a; 0.1 b; 0.1 c; 0.2 d		5.0 a
Grapes	Vitis vinifera	78.35 ± 3.55	46.25 ± 5.22	12.65 ± 0.81	BLD	20.74 ± 12.80	14.39 ± 3.95	1240.40 ± 127.27	1125.31 ± 84.77
Maximum levels (mg/kg)		-		0.20 a,b,c,d		0.5 a; 0.3 b; 0.3 c; 0.3 d		-
Leafy vegetables
Cabbage	Brassicaoleracea convar. capitata (L.) f. alba L.	BLD	BLD	BLD	BLD	BLD	BLD	2565.82 ± 133.88	1473.58 ± 171.45
Lettuce	Lactuca sativa L. convar. capitata (L.)	BLD	BLD	36.16 ± 4.58	33.20 ± 7.66	94.52 ± 4.53	73.14 ± 1.97	1031.40 ± 17.28	2064.13 ± 61.28
Bulbs
Maximum levels (mg/kg)		0.5 a		0.1 a; 0.05 b; 0.1 c,d		0.5 a; 0.1 b,c,d;		15.0 a
Garlic	Allium sativum ssp. vulgare	167.03 ± 12.94	129.89 ± 4.11	BLD	BLD	BLD	BLD	4682.37 ± 113.49	4731.25 ± 477.80
Root vegetables
Maximum levels (mg/kg)		0.5 a		0.1 a; 0.1 b,c,d		0.5 a; 0.1 b,c,d;		15.0 a
Potato	Solanum tuberosum	BLD	BLD	BLD	BLD	60.24 ± 5.33	30.50 ± 15.07	5628.20 ± 775.49	6022.00 ± 120.16
Carrot	Daucus carota L. conv. sativus	BLD	BLD	BLD	BLD	BLD	BLD	943.34 ± 45.57	BLD

^a Maximum permissible limit according to the Romanian Ministry of Agriculture Food and Forestry Order No. 293/640/2001-1/2002 on the security and quality conditions for fresh fruit and vegetables for human consumption (M.Of 173/13 March 2002); ^b Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. ^c Maximum permissible limit according to the Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (FAO-WHO 2011); ^d Maximum permissible limit according to the Romanian Health Minister Order no. 1201/106/2003 the approval of food contaminants regulation (M.Of. 142/17 February 2004). BLD = below the detection limit (LoQ); LoQ for As: 0.743 µg/L; LoQ for Cd: 0.069 µg/L, LoQ for Pb: 0.231 µg/L. FW = fresh weight. Average value ± standard deviation (SD).

).

Pb concentration varied in the range of < LoQ (LoQ for Pb: 0.231 µg/L) to 102.45 µg/kg FW, with an average concentration of 32.07 µg/kg FW. Leafy vegetables (41.92 µg/kg FW), fruiting vegetables (38.08 µg/kg FW), root vegetables (30.25 µg/kg FW), and fruits (28.09 µg/kg FW) recorded the highest Pb concentrations, while the lowest Pb concentration was recorded in bulbus (< LoQ). The maximum concentrations of Pb were observed in long cucumber (77.89 µg/kg FW), lettuce (83.83 µg/kg FW), pear (66.67 µg/kg FW), potato (45.37 µg/kg FW), and tomato (50.72 µg/kg FW). The lowest concentration of Pb was identified in red cherry tomato, zucchini, grapes, and yellow cherry tomato, with values between 8.55 µg/kg FW and 32.95 µg/kg FW. The concentrations of Pb in fruit and vegetable samples decreased in the order of long cucumber > lettuce > pear > potato > tomato > yellow cherry tomato > grapes > zucchini > red cherry tomato > strawberry > cabbage > garlic > carrot. Concerning the origins of the fruits and vegetables, samples collected from the vegetable market (35.59 µg/kg FW) recorded up to 27% more Pb (average value) compared to those from the amateur farmers (27.91 µg/kg FW) (Table 3).

The obtained results were below the maximum permitted limit set by national law (0.5 mg/kg), but exceeded the recommended limit in Codex Alimentarius (0.1 mg/kg). The exception to this rule was Pb concentration from the long cucumber sample (102.45 µg/kg FW) from the vegetable and fruit market, which slightly exceeded the limit recommended in Codex Alimentarius (0.1 mg/kg). From the research conducted in this study, it can be concluded that the concentrations of Zn in fruits and vegetables were significantly less influenced by the washing of the samples with 10% vinegar, as in the case of As, Cd, and Pb. Zn concentration varied in the range of 377.08 to 6022.00 µg/kg FW, with an average concentration of 2629.32 µg/kg FW. Bulbus (4706.81 µg/kg FW), root vegetables (4197.85 µg/kg FW), and fruiting vegetables (3044.84 µg/kg FW) recorded the highest Zn concentrations; the lowest Zn concentrations were recorded in leafy vegetables (2033.73 µg/kg FW) and fruits (926.35 µg/kg FW) (Table 3).

The maximum concentrations of Zn were observed in potato (5628.20 µg/kg FW—samples from vegetables and fruit market, and 6022.00 µg/kg FW–samples from amateur farmers), and garlic (4682.37 µg/kg FW—samples from vegetables and fruit market, and 4731.25 µg/kg FW—samples from amateur farmers). The lowest concentrations were identified in pear (393.68 µg/kg FW) and carrot (943.34 µg/kg FW). The concentrations of Zn in fruit and vegetable samples decreased in the order of > potato > garlic > red cherry tomato > yellow cherry tomato > tomato > cabbage > long cucumber > zucchini > grapes > strawberry > lettuce > carrot > pear. Concerning the origins of the fruits and vegetables (vegetable market or amateur farmers), samples collected from the amateur farmers (2780.62 µg/kg FW) recorded up to 6% more Zn (average value) compared to the vegetable market (2623.79 µg/kg FW). The obtained results were below the maximum permitted limit set by national law (5 and 15 mg/kg) (Table 3).

Washing with 10% vinegar can be recommended for fruit and vegetables, regardless of where they were purchased (vegetable and fruit market or amateur farmers) as this operation reduces considerably the concentration of As, Cd, and Pb. The analyzed heavy metals follow the same reduction trend as in the case of washing with 5% vinegar. The results of the analysis showed reductions of up to 45% for As, 65% for Cd, and 33% for Pb. The concentrations of these elements in the samples washed with water were 121.94 µg/kg FW for As, 15.78 µg/kg FW for Cd, and 42.71 µg/kg FW for Pb, while the concentrations of As, Cd, and Pb in samples of fruit and vegetables washed with 10% vinegar were 84.16 µg/kg FW for As, 9.55 µg/kg FW for Cd, and 32.07 µg/kg FW for Pb. Regarding Zn, the results showed a slight reduction of up to 13% compared to washing with water (from 2983.51 µg/kg FW to 2629.32 µg/kg FW) (Table 3).

Previously published data on As [34,35,36,37,38], Cd [36,37,44,45,46,47], Pb [18,35,36,37,44,45,46,47,48,54], and Zn [17,18,34,35,45,47,54,57,58,59,60,61] are comparable to the findings from the present study. The results obtained are also comparable with previous research carried out on samples of fruits and vegetables from Romania [16,49,50] and Moldavia [38]. In the research conducted by Singh et al. (2006) [62] on okra (Abelmoschus esculentus L.) and spinach (Spinacia oleracea L.) grown extensively in the peri-urban Delhi location, washing the samples 2–3 times with clean tap water led to drastic reductions in Pb and Cd concentrations (75–100%) as well as Cu and Zn levels (27–55%). Similar results were obtained by Yusuf et al. (2009) [63] on soko (Celosia argentea), green (Amaranthus viridis), ugwu (Cucurbita maxima), ewedu (Corchorus olitorius), and waterleaf (Talinum triangulare).

3.4. Lowering the Heavy Metal Concentration Using 5% and 10% Vinegar

Based on the results obtained in this research, it can be seen that a simple wash with tap water ensures a low concentration of heavy metals, especially for As, Cd, and Pb. However, washing samples with 5% vinegar resulted in 33% to 37% lower concentrations in As, Cd, and Pb as compared to washing with tap water (

Table 4. The concentrations of heavy metals analyzed in samples of fruit and vegetables washed with tap water and 5% vinegar.

Element	Washing with Water	Washing with Vinegar (5% Acetic Acid)
As (µg/kg)	121.94	90.49
Cd (µg/kg)	15.78	11.48
Pb (µg/kg)	42.71	32.15
Zn (µg/kg)	2983.51	2836.13

; Figure 1). However, washing samples with 5% vinegar resulted in 33% to 37% lower concentration in As, Cd, and Pb as compared to tap water (Table 4).

Fruit and vegetable samples washed with 10% vinegar recorded an even more pronounced reduction in heavy metal concentrations, with values ranging between 33% and 65% (

Table 5. The concentration of heavy metals analyzed in samples of fruit and vegetables washed with tap water and vinegar (10% acetic acid).

Element	Washing with Water	Washing with Vinegar (10% Acetic Acid)
As (µg/kg FW)	121.94	84.16
Cd (µg/kg FW)	15.78	9.55
Pb (µg/kg FW)	42.71	32.07
Zn (µg/kg FW)	2983.13	2629.32

).

Fruit and vegetable samples washed with 10% vinegar recorded an even more pronounced reduction in heavy metal concentrations, values ranging between 33% and 65% (Table 5; Figure 2).

Regarding the efficiency of the vinegar, small differences were observed between the 5% and 10% vinegar results (

Table 6. The difference between the heavy metal concentrations in samples of fruit and vegetables washed with tap water and vinegar (5% and 10% acetic acid).

Element	Washing with Vinegar (5% Acetic Acid)	Washing with Vinegar (10% Acetic Acid)
As (µg/kg FW)	90.49	84.16
Cd (µg/kg FW)	11.48	9.55
Pb (µg/kg FW)	32.15	32.07
Zn (µg/kg FW)	2836.13	2629.32

).

Regarding the efficiency of the vinegar, small differences were observed between the 5% and 10% vinegar results (Table 6; Figure 3).

These results suggest that fruit and vegetable samples analyzed in this study were subjected to slight atmospheric pollution. This atmospheric pollution can be attributed to the positioning of cultivation areas near heavily trafficked roads and highways, the use of plant protection products and fertilizers with direct application on plants, and improper handling.

4. Conclusions

It is generally observed that fruiting vegetables, bulbus, and fruits have higher concentrations of As compared to leafy vegetables and root vegetables. Lower concentrations of As were identified in strawberry, watermelon, chestnut, grapes, cabbage, dill, lettuce, and celery. Concerning the origins of the fruits and vegetables (vegetable market or amateur farmers), samples collected from the vegetable market recorded up to 35% more As (average value) compared to those from amateur farmers. The obtained results were below the maximum permitted limit set by national law (0.5 mg/kg), but exceeded the recommended limit in Codex Alimentarius (0.1 mg/kg). The highest concentrations of Cd were observed in long cucumber, lettuce, potato, red beans, yellow cherry tomato, white beans, and tomato. The lowest concentrations of Cd were identified in raspberry, watermelon, chestnut, apples, plums, quince, cabbage, tarragon, parsley, lovage, dill, celery, garlic, and carrot. In this case, samples collected from the vegetable market (9.81 µg/kg FW) recorded up to 68% more Cd (average value) compared to those from amateur farmers (5.83 µg/kg FW). The obtained results were below the maximum permitted limit set by national law (0.05 mg/kg) and FAO-WHO (0.2 mg/kg). High concentrations of Pb were also recorded in tomato, yellow cherry tomato, pear, and dill, while the lowest concentrations were identified in red cherry tomato, kirby cucumber, zucchini, raspberry, blueberry, strawberry, watermelon, bell pepper, chestnut, apples, plums, quince, grapes, cabbage, tarragon, parsley, lovage, celery, garlic, onion, parsley, and carrot. Samples collected from the vegetable market recorded up to 67% more Pb (average value) compared to those from amateur farmers. The highest concentrations of Zn were observed in potato, garlic, tarragon, tomato, red cherry tomato, and chestnut. Concerning the origins of the fruits and vegetables (vegetable market or amateur farmers), samples collected from the amateur farmers recorded up to 3% more Zn (average value) compared to those from the vegetable market. The obtained results were below the maximum permitted limit set by national law (5 and 15 mg/kg).

Based on the studies and on the statistical analysis performed, washing with either 5% or 10% vinegar can be recommended for fruit and vegetables, as both procedures resulted in a significant reduction in heavy metal concentrations as compared to washing with tap water.

Regarding the efficiency of the vinegar, it can be seen that in the case of the concentrations of metals in fruit and vegetable samples washed with 5% vinegar and 10% vinegar, there were quite small differences. It is also noted that As and Zn recorded concentration levels up to 8% lower for samples washed with 10% vinegar. The biggest difference between samples washed with 5% vinegar and those washed with 10% vinegar was found in the case of Cd; this heavy metal recorded concentration levels up to 20% lower for samples washed with 10% vinegar, while Pb did not register any differences.