Analysis of physicochemical attributes, contamination level of trace metals and assessment of health risk in mango fruits from Southern region Ethiopia

Abstract

Heavy metal pollution has become one of the most threats that can endanger human health due to accumulation and consumption of fruits. Our study was aimed to evaluate physicochemical quality parameters, level of heavy metals, and assessment of health risks of lead (Pb), Manganes (Mn), zinc (Zn), iron (Fe), copper (Cu), chromium (Cr), and cadmium (Cd) in mango fruits from Arba Minch, Wolaita Sodo, and Damote Gale study areas. Quality parameters such as, total soluble solid, moisture, ash, titratable acidity, pH, total sugar, reducing sugar and non-reducing sugar, fat and fiber content of mango fruit were ranged between 15.68° and 18.92°B, 81.080–84.320 %,g, 4.040‐4.080, 11.56‐12.95%, 10.07‐12.54%, 1.60‐3.83%,0.397‐0.673%, and 1.338‐2.375% 0.283–1.030 %, 0.311–0.366 mg/100 g, 4.040–4.080, 11.56–12.95 %, 10.07–12.54 %, 1.60–3.83 %,0.397–0.673 %, and 1.338–2.375 % respectively. The average levels of metals in mango fruits were in the range Fe (1.166–1.486 mg/kg), Cu (0.019–0.198 mg/kg), Mn (0.121–0.239 mg/kg), Zn (0.134–0.321 mg/k), Pb (0.035–0.097 mg /kg) and Cd (0.193 mg/kg). Chromium is not detected in our study, because its level is below the detection limit. On average within metals, the highest level was obtained in Fe in the range 1.166–1.486 mg/kg, whereas the minimum level was determined in Pb from 0.035 to 0.097 mg/kg. The EDI values of accumulated elements in mango fruits follows the increasing order as; Fe $>$ Zn > Mn > Cu > Cd > Pb. Except Damot Gale sample in moderate range, the values of total carcinogenic risks (TCR) in all metals were less than 1 × 10⁻⁶, which is considered to be safe. All THQ and HI values were $<$ 1, which indicates that the accumulated metals did not contribute risk for human health. The present study clearly indicated that the consumption of mango fruits in the studied areas does not pose any health hazard associated with any of the selected heavy metals.

1. Introduction

Fruits are the major components of the human diet, as it is the source of essential micronutrients [1]. Mango (Mangifera indica) belongs to the Anacardiaceae family and in the order of Sapindales is grown in many parts of the world, particularly in tropical countries [2]. Ethiopia produces mango in Amhara, Oromia, Harari, Benishangul Gumuz, and southern regions. Mango in Ethiopia is the second most abundant known edible fruit next to banana [3]. Ethiopia has many resources and diverse environmental conditions to produce fruit like banana, mandarin, papaya, mango, avocado, strawberry, apple and any others. The quality performance of mango fruits depends on physical and chemical quality parameters. Internal quality attributes comprise a uniform and intense flesh color, and contain adequate acidity, vitamins, and a pleasant sweetness [4], [5].

Mango growing farmlands play an important role in agricultural production, so the potential contamination of farmland deserves special attention [6]. In recent years; soil quality has been compromised by heavy metals pollution. Pollution by heavy metals has been considered one of the main environmental problems due to their toxicity and persistence, and their harmful effects on the environment [6], [7]. Heavy metals have serious complications, including mutagenic effects, carcinogenic effects, toxicity, accumulation in adipose tissue, and long shelf life [8]. During plant growth period, some of important elements for growth and development like Mg, Fe, Mn, Zn, Cu, and Ni are usually taken from the soil. However, plants also can accumulate other elements including Cd, Cr, Ag, Se, Pb, and Hg, which have acute and chronic toxicity effects in the human body [9]. Regular consumption of mango fruits that are contaminated with toxic heavy metals has the favorable ability to become a threat to human health [10]. Metals can enter the human body through defined routes, including inhalation of contaminated particulate matters, direct ingestion of contaminated soil deposited on the surface of foods and fruits, and ingestion of food containing metals due to contamination [9]. Non-essential metals such as Cd, Pb, Hg, As, and Ag do not have any biological function, and due to this, they simply hinder chemical processes [11]. Although mango fruits provide health benefit, the accumulation of contaminants like metals in the bodies of consumers over a long period of time is of the major concern as it can result to serious health conditions [12]. The ingestion of food including mango fruit is an obvious means of exposure to metals, not only because many metals are natural components of food stuffs, but also environmental contamination and contamination during processing [13]. Source of heavy metals pollution includes agricultural activities, industrial activities, vehicular emission, nuclear waste, and agrochemicals etc. These sources accumulate heavy metals in the environment, leading to a level that can pose ecological and health risk [9], [14]. Nowadays, the main research interest is to develop alternative solutions to the problem of heavy metal polluted soil without deteriorate the physical structure of the ecosystem, their biological activities, and chemical properties [15]. Food contamination by heavy metals has become a public health concern, and there is lack of knowledge about this issue in many developing nations, including Ethiopia [16]. Long-term exposure to heavy metals causing permanent intellectual, developmental and behavioral problems [17]. Trace element level evaluation is a performant method that has been used to estimate the quality, as well as safety of food and fruits [18]. Some of previous studies estimated only the pollution level by comparing the metal levels with standard value. But due to the high toxicity of heavy metals, a simple comparison is not sufficient enough to evaluate their negative effects on humans [19]. However, up to now, no detailed research works have been reported on mango fruit quality assessment and associated human health risk in Arba Minch, Wolaita Sodo, and Damot Gale. In fact, there is a knowledge gap about impact of toxic metals on human health in these study areas. Understanding the pollution level, quality status, and health risk due to heavy metals in mango is important to controle and manage the polluted areas. Based on the above aforementioned reason, the objective of this study was to (i) determine the level of heavy metals (Zn, Cu, Mn, Fe, Cr, Cd and Pb) in mango fruits; (ii) assess mango fruit quality parameters by comparing with other related works and quality standards (iii) evaluate potential human health risk in terms of daily intake of metals, target hazard quotient, hazard index, and carcinogenic effects for adults. The finding of this study will provide scientific information for food, health and pollution agencies to guide quality remediation and protect human from heavy metal exposure.

2. Material and Methods

2.1. Study area description

This work was performed in Ethiopia specifically in Arba Minch, Wolaita Sodo and Damote Gale. Arba Minch is the zonal capital of Gamo zone in southern nation, nationalities and peoples (NNNP) regional state of Ethiopia. The Latitude and Longitude of the town is mainly found as 6°04′ North and 36°40′ East respectively. Wolaita Sodo is the largest town situated in southwest 327 km far from Addis Ababa. Wolaita Sodo is the zonal capital of Wolaita in southern regional state of Ethiopia. An altitude of the town is 1500–2500 m above sea level with an area of 82.1 km². Damot Gale is one of the woredas in (SNNP) region of Ethiopia. It is bordered with Sodo zuria, Hadiya, Diguna Fango, Damot Weyde, on southwest, North, East, and Southeast respectively. Boditi is the administrative center of Damot Gale. This town has a latitude of 6°58′N and longitude of 37°52′E with an elevation of 2050 m above sea level. Due to wide range of mango production and release of agrochemicals, weathering of soil and rock, environmental erosion, and disposal of waste materials, it is important to analyse the quality of produced mango for the consumers of local population in these study areas.

2.2. Chemicals and equipments

The reagents and chemicals used to determine the level of trace metals and physicochemical quality testing were analytical grade. Fehling solutions, A and B were used to determine reducing sugars. Sodium hydroxide Loba chemie Ltd, India) was used for the determination of titratable acidity and fiber content. A solvent like petroleum ether (Loba chemie PVT. Ltd. India) was used for the evaluation of the composition of fat. Refractometer (abbe 60/DR, UK code 10–99) was applied to estimate the composition of total soluble solids. pH meter (Model: HI 99121, Romania) was equipped to evaluate the pH of the solutions. Concentrated nitric acid (69–72 %) (LOBA CHEMIE PVT LTD, India) and perchloric acid (70 %) (Sisco research Laboratories PVT LTD, India) were used for the digestion of mango fruit. For the selected metals such as Fe, Cr, Mn, Zn, Cu, Cd and Pb, respective stock solutions 1000 mg/L were used to prepare intermediate and series of working standard solutions for the generation of calibration curve. Drying oven (UF 260 memmert) was used for evaporation of moisture and drying of mango fruit samples. Electrical digital balance (AKERNABJ-NM/ABS-N, Germany) was used to measure the weight of samples. Muffle furnace (FUSEF1AH, R000047 UK) was used for ashing purpose. For the analysis of metals, Flame Atomic Absorption spectrophotometre (Buck scientific model, 210 VGP) was applied. All glassware’s were soaked in 5% nitric acid overnight, cleaned thoroughly with distilled water.

2.3. Sample collection and preparation

For the present investigation, sampling sites from Arba Minch, Wolaita Sodo, and Damot Gale were selected because these areas are known by producing the maximum mango fruits. Fresh samples of commonly edible Kent mango fruits cultivar were purchased from local markets of Arba Minch, Wolaita Sodo, and Boditi. A total of twenty seven ripe mango fruit samples (n = 27), nine (n = 9) for each sample sites were purchased with their appropriate season on first June 2022, which is appropriate ripening period of mango fruits. Within these market areas, representative samples were collected at random from different known vendors and retailers and samples were pooled together. After collection of fruit Samples using polyethylene bags different pretreatment activities were made in the laboratory. To remove any contaminant the samples thoroughly washed with tape water followed by distiled water. The skins of the fruit were removed using stainless steel knife and the pulp was separated from kernel. The extracted sample was dried using oven at 80 $℃$ to obtain a constant weight [14], [20]. The dried samples were changed into fine powder using a grinder for the analysis of trace metals and further experiments.

2.4. Analysis of physicochemical parameters in mango fruit samples

2.4.1. Estimation of total soluble solids (TSS)

Total soluble solids (TSS) content is considered as a measure of quality for most of the fruits [21]. The TSS was determined by using refractometer methods (abbe 60/DR, UK code 10–99). A 1 mL of mango juice was placed on prism of calibrated refractometer. The readings were applied and the results expressed in degree of brix (°Brix) at ordinary temperature.

2.4.2. Analysis of moisture content

The percentages of moisture values were determined using the methods of AOAC as a reference [22]. Briefly, fifteen gram of mango sample were taken in a crucible and allowed under overnight by setting the ovens temperature at 80 °C for 24 hr. The attainment of moisture was considered as the level of any moisture present in the sample. The values estimated using the following Eq. (1).

$$\mathrm{Moisture}content(\%)=\frac{\mathit{Weight}\mathit{of}\mathit{fresh}\mathit{sample}-\mathit{weight}\mathit{of}\mathit{dry}\mathit{sample}}{\mathit{weight}\mathit{of}\mathit{fresh}\mathit{sample}}\mathrm{x}100$$ (1)

2.4.3. Evaluation of ash content

Eight gram of mango pulp was weighed and introduced into the crucible and ignited in hot plate until the minerals weight achieved. Then, the sample was placed in the muffle furnace at a temperature of 550 $℃$ for 6 hr until total removal of carbon [23]. The ash containing crucible was cooled and the amount of ash weighed. Heating in the furnace and cooling were repeated until the constant weight was obtained. The ash content of samples was determined using Eq. (2).

$$\mathrm{Ash}content(\%)=\frac{\mathrm{Weight}\mathrm{of}\text{\hspace{0.17em}a}\mathrm{sh}}{\text{Weight of sample}}\mathrm{x}100$$ (2)

2.4.4. Analysis of pH values

The pH is an important quality parameter for fruits and vegetables since the growth of microorganisms affected by its values [23], [24]. The fruits from each sample sites were treated for the pH estimation at a calibrated scale [4]. The values of pH for each sample were evaluated by using digital pH meter (Model: HI 99121, Romania). The analyses were made at pH 4.0 and 7.0 buffer solution to calibrate the pH meter.

2.4.5. Quantification of titratable acidity

The amount of titratable acidity was evaluated by titrating against NaOH [4]. For quantitative analysis, ten grams of fruit powder was diluted by 250 mL deionized water. Out of prepared solutions, 50 mL of solution was used for titrations followed by the addition of 2 mL of phenolphthalein indicator and titrated against 0.1 N NaOH solutions until the pink color noted. The amount of titratable acidity expressed as mg of citric acid per 100 g of mango sample using the following formula.

$$\mathrm{Titratable}acidity=\frac{\text{T}\mathrm{iter}\left(\mathrm{ml}\right)\mathrm{x}N\left(\mathrm{NaOH}\right)\mathrm{x}\mathrm{dilution}\mathrm{x}\mathrm{equivalent}weight}{\text{W}\mathrm{eight}\mathrm{of}\mathrm{the}\mathrm{sample}\mathrm{taken}\mathrm{x}\mathrm{volume}\mathrm{taken}x1000}\mathrm{x}100$$ (3)

2.4.6. Determination of total sugar level

The accumulated sugar contents were evaluated by the method modified by [24]. A volume of 50 mL of the supernatant was transferred to a 100 mL volumetric flask. Immediately 5 mL of concentrated hydrochloric acid was added and allowed to stand at ordinary temperature for 20 hr. The solution was prepared as a stock by distiled water. Afterwards, fifty milliliter of the solution was neutralized against 0.1 N NaOH solution from the burette. The titrations were performed using Fehling solutions with similar to the procedures described for the determination of reducing sugar by (AOAC 2000). The amount of total sugar level was calculated using Eq. (4).

$$\text{Total sugar(\%)=}\frac{Fehling\prime sfactorxdilution}{Weightofsamplextitrevalue}x100$$ (4)

2.4.7. Determination of the level of reducing sugar

Reducing sugar was analysed by the method explained by [24], [25] with simple modification. A 25 g of fruit powder was added into 200 mL volumetric flask to prepare as 150 mL stock solution. After complete dissolution of sugar, 10 mL of lead acetate and small amount of sodium oxalate solutions were added. The final volume of the solution was adjusted to 200 mL, and the solution shaken, filtered, and transferred into a burret for titration. A 5 mL of each Fehling solutions A and B, and 35 mL of distiled water were transferred to a flask. The solution was boiled until de-colorization of Fehling solutions. Two drops of methylene blue was added, and heating continued for 5 min. Reducing sugar was calculated using the following formula.

$$\mathrm{Reducing}sugar(\%)=\frac{\mathrm{Fehling}\mathrm{factor}\mathrm{x}dilution}{\mathrm{Titre}\mathrm{x}\mathrm{Weight}\mathrm{or}\mathrm{volume}\mathrm{of}sample}\mathrm{x}100$$ (5)

2.4.8. Estimation of non-reducing sugar

Non-reducing sugars were measured according to the method adopted by the Association of Official Analytical chemists [24], [25]. Non-reducing sugar was determined by the differences between the total sugar level and reducing sugar contents estimated in mango fruit samples. The amount of non-reducing sugar was obtained using the following formula.

Non-reducing sugar (%) = Total sugar (%) – reducing sugar (%) (6)

2.4.9. Fiber content analysis

The total fiber content was estimated by using the procedure described by (AOAC 2000) [24] with simple modifications. For analysis, eight grams of fruit powder mixed with 200 mL of H₂SO₄ solution and the mixture was heated for 35 min. The residue was washed with boiled water and mixed with 100 mL of 1.5 % NaOH followed by heating and filtration. Afterwards, the residue was washed with boiled water to be free from the acid. Finally, wet materials were removed and dryness were made by oven drier at 105 $℃$ overnight and weighed. The residue was ashed in a muffle furnace at 550 $℃$ 2 h. The composition of fiber was conducted using the following Eq. (7).

$$\mathrm{Fiber}(\%)=\frac{W\mathrm{eight}\mathrm{of}\mathrm{sample}\mathrm{before}ashing-\mathrm{weight}\mathrm{of}\mathrm{sample}\mathrm{after}ignition}{\mathit{\text{Original sample weight}}}\mathrm{x}100$$ (7)

2.4.10. Evaluation of fat in mango fruit

The composition of fat in mango fruit was determined by the method mentioned by (AOAC 2000) [23], [24]. Four grams of sample was weighed transferred into soxhlet apparatus, 250 mL of petroleum ether was added and heated at 85$℃$ until the total removal of solvent. Then, sample was cooled in desiccator. The fat content was calculated using the following formula.

$$\mathrm{Fat}content(\%)=\frac{\text{W}\mathrm{eight}\mathrm{of}bottle-\mathrm{weight}\mathrm{of}\mathrm{empty}bottle}{\text{W}\mathrm{eight}\mathrm{of}sample}\mathrm{x}100$$ (8)

2.5. Trace metal analysis of mango fruit

In this study, the wet digestion system was adopted to determine the level of metals in mango fruits samples. The optimized digestion procedure was applied, based on clarity of digests, minimum volume ratio, minimum digestion time, and low temperature. Based on optimized condition as above, 0.5 g of dried mango fruit sample was weighed and transferred into 100 mL conical flask. Briefly, 5 mL of HNO₃ (69–72 %) and 3 mL of HClO₄ was added and digested on hotplate by setting the temperature at 150 $℃$ for 1:00 hr until a clear and colorless solution was obtained. The solutions were allowed to cool for 1:30 hr. The cooled solutions were filtered into 50 mL volumetric flask with whatman filter paper (No 42) to remove debris and insoluble solid contaminants. Finally, each digested sample was filled with distiled water up to the mark. Digestion of blank solution was also performed in parallel with the same digestion procedure as samples. The prepared solutions were kept in refrigerator at 4 $℃$ for further experiments and analysis [26], [27].

2.5.1. Instrument calibration

As a result, several series of working standard solutions were prepared from 20 mg/L intermediate solution. For efficient determination, the instrument was adjusted by calibration blank solution. Flame atomic absorption spectrometer equipped with deuterium arc background correctors and respective hollow cathode lamps with an air acetylene flame were used for the determination of the level of metals in mango fruit samples. For the evaluation of the level of metals in samples, the calibration curve of the known concentration of standards was used for each metal of interest. The metals such as Zn, Cu, Cd, Pb, Fe, Cr, and Mn were analysed based on their calibration curve after slit width, wavelength, lamp alignment and burner were adjusted for maximum signal intensity and efficiency of the instrument [27], [28]. Calibration curve involves making of a comparison of a measured quantity against reference value. Operating parameters such as series of concentrations, wavelength, regression equation and correlation coefficients are summarized as in Table 1.

Table 1.

FAAS operating parameters for the evaluation of metals.

Metal	wave length (nm)	slit width (nm)	lamp current (mA)	Fuel type	Support
Fe	248.3	0.75	6.4	Acetylene	Air
Zn	213.9	1.0	5.0	Acetylene	Air
Mn	279.8	0.77	3.0	Acetylene	Air
Cu	324.7	1.0	1.5	Acetylene	Air
Cr	357.9	0.5	6.0	Acetylene	Air
Pb	217.0	1.0	5.0	Acetylene	Air
Cd	228.8	0.5	4.2	Acetylene	Air

2.5.2. Validation of analytical methods for mineral analysis

Appropriate working parameters like slit width, wavelength, lamp current, oxidant or fuel type were indicated Table 1. For this study, the reliability of the optimized digestion procedure was checked by testing with lower level of traceability such as spiked the given samples. In order to increase the efficiency of our method, method validation testing parameters such as limit of quantification, limit of detection, accuracy, and precision were applied. The average levels of selected metals were determined based on the use of regression equation and comparing with the correlation coefficients (R²) Table 1. For quality controle techniques and method performance analysis, the quantitative determinations of metals were performed by preparing known concentrations of 0.1, 0.25, 0.5, 1, 2 mg/L. As the results showed in Table 2, the limit of detection (LOD) for Fe, Zn, Mn, Cu, Cr, Pb, and Cd were 0.0234, 0.0063, 0.0096, 0.0036, 0.105, 0.0033, 0.006 mg/L, while the limit of quantification (LOQ) values were 0.078, 0.021, 0.032, 0.012, 0.35, 0.011, 0.02 mg/L respectively [28], [29], [30]. The largest values of regression coefficient (R²) in the range 0.9926–0.9990 indicate the highest correlation between absorbance and concentrations of metals.

Table 2.

Concentrations, correlation coefficients, and regression equation for evaluation of metals using FAAS.

Metal	concentration (mg/L)	regression equation	R2	LOD	LOQ
Cu	0.1, 0.25, 0.5, 1, 2	A = 0.0828x + 0.0058	0.9990	0.0036	0.012
Mn	0.1, 0.25, 0.5, 1, 2	A = 0.1613x + 0.01	0.9926	0.0096	0.032
Zn	0.1, 0.25, 0.5, 1, 2	A = 0.0648x + 0.0116	0.9932	0.0063	0.021
Fe	0.1, 0.25, 0.5, 1, 2	A = 0.343x + 0.0034	0.9966	0.0234	0.078
Pb	0.1, 0.25, 0.5, 1, 2	A = 0.1957x + 0.012	0.9958	0.0033	0.011
Cr	0.1, 0.25, 0.5, 1, 2	A = 0.022x + 0.0012	0.9979	0.105	0.35
Cd	0.1, 0.25, 0.5, 1, 2	A = 0.1414X + 0.0131	0.9974	0.006	0.02

2.6. Assessment of health risks in mango fruits

Assessment of health risk is important for regulatory bodies to control the main sources of metal pollution. The target hazard quotient (THQ) and hazard index (HI) were used to explain the possible health risks to humans [30], [31]. Target Hazard Quotient (THQ) was used to analyse non-carcinogenic risks associated with the uptake of hazardous metals by consumption of mango fruits [30]. In this assessment, the daily consumption of each hazardous element was evaluated, and the value of THQ was also determined using the oral reference dose of each metal. The value of THQ is determined by adding the THQ values of all metals levels in mango fruit. If the THQ $<$1 which is considered to be an acceptable risk in terms of chronic effects, while if THQ $>$ 1, the risk of non-carcinogenic would be unacceptable [32].

2.6.1. Determination of estimated daily intake of metals (EDI)

The estimated daily intake of metals was determined using the methods developed by [33], [34]. EDI was designed using the following Eq. (9).

$$\mathrm{EDI}=\frac{\mathrm{C}\mathrm{x}IR}{\mathrm{BW}}$$ (9)

Where, C- metal concentration in mg/kg, IR- ingestion rate of metals in g, BW - the average body weight in kg. The average body weights of adult population were considered as 67.0 kg for males, and 62.3 kg for females. The average daily consumption of mango fruit reported in the literature was 55 g/day/person for both male and female [22], [35].

2.6.2. Target hazard quotient (THQ)

Target hazard quotient is used to assess the non-carcinogenic risk to humans from long term exposure to toxic metals from mango fruits uptake. Non-carcinogenic risks for each heavy metal were assessed by calculating target hazard quotient (THQ) using Eq. (10) [33], [36].

$$\mathrm{THQ}=\frac{\mathit{EDI}}{\mathit{RfD}}$$ (10)

Where, EDI- estimated daily intake of metals mg/kg/day, RfD- oral reference dose of metals mg/kg/day. RfD is the healthy, acceptable reference dose of individual metals recommended for each weight of mango fruit by Wealth Health Organization [37]. The recommended oral reference dose of metals for Cu, Zn, Pb, Cd, Fe, and Mn were 0.04, 0.3, 0.02, 0.0005, 0.7, 0.14 mg/kg/day respectively [38], [22], [39].

2.6.3. Hazard index (HI)

The hazard index (HI) helps to evaluate the total non-cancer risk to human health from the consumption of more than one toxic metal. It is calculated by adding the target hazard quotient of all metals as described in the following formula [38].

$$\mathrm{HI}={\sum }_{\mathrm{1}}^{\mathrm{n}}{\mathrm{THQ}}_{\mathrm{Fe}}{+\mathrm{THQ}}_{\mathrm{Mn}}{+\mathrm{THQ}}_{\mathrm{Zn}}{+\mathrm{THQ}}_{\mathrm{Cu}}{+\mathrm{THQ}}_{\mathrm{Cd}}{+\mathrm{THQ}}_{\mathrm{Pb}}$$ (11)

Where, HI- hazard index, THQ- target hazard quotient. The estimated HI is related to standard levels: the inhabitant is considered as safe when HI < 1, there is health risk when 1 < HI [22], [30].

2.6.4. Carcinogenic risk assessment (CR)

The assessment of carcinogenic risk (CR) predicts the probability of an individual developing cancer over a lifetime due to exposure to the potential carcinogen and it is calculated by equation (12) [28].

CR = CSF x EDI (12)

Where, EDI- daily intake of metals, CSF- cancer slope factor mg/kg/day. According to USEPA, (2011), CR between 1 × 10⁻⁶ to 1 × 10⁻⁴ represents a range of permissible predicted life time risks for carcinogens. Chemical for which the risk factor falls below 1 × 10⁻⁶ may be eliminated from risk for carcinogens [14].

The total cancer risk because of exposure to more than one toxic metal taken from a specific mango sample assumed to be the sum of each metal incremental lifetime most cancers risk [40].

$$\mathrm{TCR}=\sum _n^i\mathit{CR;}\mathrm{n}=1,2,3\dots \dots \dots .\mathrm{n}$$ (13)

Where, TCR- total cancer risk due to heavy metal intake mg/kg/day, n-number of metals selected for cancer risk estimation. The proposed values of CSF were 0, 0.0085, 0.38 mg/kg/day for Zn, Pb, and Cd respectively [14], [40], [41].

3. Statistical analysis

The statistical analysis of physicochemical properties and level of heavy metals obtained from this study were evaluated by SPSS-21 software (SPSS Inc., Chicago, IL, USA). The analysis of variance, one-way (ANOVA) tests were applied to identify heavy metals distribution based on the sampling sits were significantly different (p $<$ 0.05). All obtained data were estimated as mean ± SD.

4. Result and discussion

4.1. Physicochemical parameters

The results of physicochemical properties of mango fruit samples from our study areas were presented in Table 3. From our investigation, the total soluble solid value (°B) showed significantly difference (p $<$ 0.05). The total soluble solid values were 15.68, 18.92, 17.46 °Brix for Arba Minch, Wolaita Sodo, and Damote Gale samples respectively. The maximum value was found in Wolaita Sodo (18.92°B) followed by Damot Gale (17.46°B). The minimum result was recorded in Arba Minch (15.68) °Brix Table 3. According to the research findings in Sri Lanka [42], the results were varied from 16.56% to 20.17% indicating that lower than this study. The current investigation was in agreement with the previous study [4], [43], [44], whose value ranged in 18.1–18.9 °B, 16.90–22.41°B, 14.05–22 °B and 18.13 °B [23]. Total soluble solids and acidity of fruits are directly correlated. As acidity of fruit decreases, amount of total soluble solids increases during maturity and ripening stage of fruit [45]. Changes in TSS during fruit ripening are mainly associated with the increase alteration of carbohydrate to simple sugars [46]. The TSS of 15 °B and above at rip stage is recommendable for products like fruit juice, nectar, and jam products [21]. In this study, TSS has strong implication on the choice of the fruit for processing as well as fresh consumption.

Table 3.

Physicochemical quality parameters of mango fruits collected in southern region Ethiopia (mean ± SD, (n = 3).

Parameters	Arba Minch	Wolaita Sodo	Damot Gale
Total soluble solid (°Brix)	15.68 ± 0.21a	18.92 ± 0.01b	17.46 ± 0.20c
Moisture content (%)	84.320 ± 0.014a	81.080 ± 0.010b	82.536 ± 0.006c
Ash content (%)	0.283 ± 0.121a	0.676 ± 0.061b	1.030 ± 0.028c
Titratable acidity (mg/100 g)	0.311 ± 0.124a	0.379 ± 0.051a	0.366 ± 0.312a
pH	4.080 ± 0.014a	4.240 ± 0.058a	4.040 ± 0.097a
Total sugar (%)	15.37 ± 0.24a	11.56 ± 0.12b	12.95 ± 0.10c
Reducing sugar (%)	12.54 ± 0.10a	10.07 ± 0.03b	10.89 ± 0.02c
Non Reducing sugar (%)	3.83 ± 0.17a	1.49 ± 0.03b	1.60 ± 0.03b
Fat content (%)	0.456 ± 0.107a	0.673 ± 0.213b	0.397 ± 0.251a
Fiber content (%)	2.375 ± 0.157a	1.482 ± 0.204b	1.338 ± 0.137b

All values determined in mean ± SD of three replicate measurements (n = 3).

An average value with different letters in the same row showed significant variations (p $<$ 0.05).

According to our findings Table 3, the percentage of moisture value of mango fruits in Arba Minch (84.320 %), Wolaita Sodo (81.080 %), and Damot Gale (82.536%). Results clearly showed a significant difference (p $<$ 0.05) in mango fruits between Arba Minch, Wolaita Sodo, and Damot Gale. All values of this study was in agreement with previous studies in Bangladesh and Nigeria indicated by [23], [47], with conducted values 86.51 % and 72.83–88.26 % respectively. On average, Pamela et al. [20] recoded the values from 77.87 to 80.44 g/100 g, which is lower than the present study. Fruits with higher moisture percentage value have a shorter shelf life due to oxidation. In general, fruits deteriorate within a short period of time due to their high moisture content [5]. The relative low moisture content in Wolaita Sodo sample promises a long shelf life processing than other Arba Minch and Damote Gale samples.

As the results Table 3 showed that, the composition of ash contents were differed significantly (p $<$ 0.05) evaluated from Arba Minch, Wolaita Sodo and Damot Gale, and the results were 0.283 %, 0.676 % and 1.030 % respectively. The ash content in Damot Gale has the maximum value compared with Arba Minch and Wolaita Sodo samples. Study results examined by [20], [23], [24] showed that, the total mineral content in mango fruits evaluated 1.47–2.67 g/100 g, 1.95 % and 1.97–2.34 %, which is greater than from our finding. In comparative, our results are partially agreed with Ethiopia [5], who evaluated (0.31–0.57 %). The maximum ash content in Damote Gale samples attributed, due to high level of important inorganic ions in mango fruit.

As a quality parameter, the values of pH were in the range between 4.040 and 4.240 Table 3. pH is one of the significant quality parameters for fruits. The measured quantities of pH, from all study areas had approximately equal amounts (p > 0.05) between samples. The smallest pH value was recorded in Damote Gale (4.04), whereas the highest value estimated in Wolaita Sodo (4.24). This study showed lower pH in relative to the previous studies [4], [20], [23], [42], [47], with the values listed as 4.6–5.6, 4.60–5.91, 4.6, (4.31–4.67), and (4.72–5.62) respectively. However, the values were comparable with 3.75–4.32 in India [44]. The variation of pH in mango fruits was due to the ripening and storage of mango reported by [24].

The values of titratable acidity expressed mg/100 g. The values were in Arba Minch (0.311 mg/100 g), Wolaita Sodo (0.379 mg/100 g), and Damot Gale (0.366 mg/100 g) Table 3. Results were tested by one-way (ANOVA) and no variations detected (p $>$ 0.05) level. Our study results were similar with the results in Sri Lanka in the range 0.35–0.68 mg/100 g reported by [42]. However, higher than in India varied from (0.01–0.29) [43], and lower than in Spain 0.17–0.21 g/100 g [4]. The decline of titratable acidity in Arba Minch may be due to susceptibility of citric acid to oxidative destruction by the ripening, storage environment, agro-geographical locations.

Crude fiber, crude fat and ash contents increased in mango powders due to the elimination of moisture content i.e. increasing concentration of nutrients [48]. Fiber has interesting properties, such as water and oil holding capacity, yield improvement, and modification of texture and viscosity [5]. The composition of fiber in mango fruits ranged from 1.338 % to 2.375 % and no significant differences were noted (p $>$ 0.05) between Wolaita Sodo and Damot Gale samples shown Table 3. The maximum value was determined in Arba Minch (2.375 %), whereas the lowest values obtained in Damot Gale samples (1.338 %). The amount of fiber content was investigated in Ethiopia from 0.37 % to 0.79 % [5], and India (0.8 %) [23], the values were lower than this study. In another study, a fiber content of mango fruits varied from 0.82 to 1.24 g/100 g [20], and 1.17–3.16 % [42], which is in accordance with our investigation. The highest fiber content of Arba Minch mango fruit regarded as valuable source of dietary fiber in human nutrition relative to Wolaita Sodo and Damot Gale samples.

The percentage of fat in mango fruits were mentioned in the range of 0.456, 0.673 %, and 0.397 % for Arba Minch, Wolaita Sodo, and Damote Gale samples respectively Table 3. The level of fat from Wolaita Sodo depicts significant difference (p $<$ 0.05) between Arba Minch and Damote Gale. The fat contents in our study was in the order Wolaita Sodo $>$Arba Minch > Damot Gale. Shaikh et al. [23] reported the values 1.6 %, which is greater than this study. But, our study values were in agreement with the value in Ethiopia, Nigeria and Bangladesh [5], [20], [24], which was estimated from and 0.14–0.47 %, 0.19–0.90 g/100 g, 0.11–1.18 % respectively.

The total, reducing and non-reducing sugar contents of mango sample evaluated in this study were (15.37, 11.56, 12.95 %), (12.54, 10.07, 10.89 %), and (3.83, 1.49, 1.60 %) for Arba Minch, Wolaita Sodo and Damot Gale samples respectively in Table 3. There is a significance difference (p $<$ 0.05) in both total sugar and reducing sugar contents. Non reducing sugar had no significant variation (p > 0.05) between Wolaita Sodo and Damot Gale. The composition of reducing sugar reported by [44], [47], were in the range 3.81–5.5 %, and 6.04–6.38 %, which is lower than this study. Experimental values from literature in Bangladesh showed that, the values of total, reducing and non-reducing sugar illustrated by [24], were in between 18.88 % and 27.55 %, 8.40–15.43 %, and 9.24–12.54 %, which is above for total sugar, comparable for reducing sugar and above for non-reducing sugar respectively. Romila et al. [44], reported equivalent amount of total sugar (12.6–17.81 %) and maximum level of non-reducing sugar (8.8–13.81 %) in India. According to Pamela et al. [20], the level of reducing sugar 0.09–0.60 g/100 g was highly lower than the present study. Based on the mean values, mango fruits are in a good quality level when compared from other country reports and locally studies.

4.2. Level of trace metals in mango fruit samples

The average levels of Cu, Mn, Fe, Zn, Cd, and Pb in mango fruits are presented in Table 4. Iron, manganese, copper, zinc, chromium, cadmium, and lead were chosen as representative heavy metals whose concentrations in the food represent a reliable index of environmental pollution [49]. The increasing order of the concentrations of metals in mango fruit samples was found to be Pb $<$Cd$<$ Cu$<$ Mn $<$Zn$<$ Fe. The level of Cr is not detected in our study, because its level is below the detection limit.

Table 4.

Estimated concentration of metals in mango fruit samples from southern region Ethiopia.

Concentrations (mg/kg) in three different areas
Metal	Arba Minch	Wolaita Sodo	Damot Gale	Mean value	CV (%)
Fe	1.486 ± 0.023a	1.166 ± 0.014b	1.283 ± 0.062b	1.312 ± 0.033	2.515
Mn	0.239 ± 0.015a	0.173 ± 0.042b	0.121 ± 0.038b	0.178 ± 0.031	17.415
Zn	0.321 ± 0.023a	0.251 ± 0.047b	0.134 ± 0.020c	0.235 ± 0.03	12.765
Cu	0.198 ± 0.009a	0.019 ± 0.007b	0.165 ± 0.004c	0.127 ± 0.007	5.511
Pb	0.035 ± 0.002a	0.097 ± 0.006b	0.068 ± 0.020c	0.067 ± 0.009	13.432
Cd	ND	ND	0.193 ± 0.031	0.193 ± 0.031	16.062
Cr	ND	ND	ND

*ND – Not detected, CV- coefficient of variance. All values estimated in triplicates, mean ± SD (n = 3). An average values with the same letters in the same row had no significant differences at (p $>$ 0.05).

The deficiency of iron in the blood can lead to the serious health problems including anemia. It is also an important metal for metabolism in the human body acting as a catalyst [50], [22]. In this study, the level of Fe ranged from 1.166 mg/kg (Wolaita Sodo) to 1.486 mg/kg (Arba Minch) samples Table 4. Based on the analytical results, Fe is found in all samples greater than the regulatory limit 0.8 mg/kg set by WHO. According to one-way (ANOVA) statistical evaluation, except in Arba Minch, the level of Fe from Wolaita Sodo and Damote Gale had no significant difference (p $>$0.05). Iron levels have been reported in mango fruit in the range from 23.10 to 42.22 mg/kg from literature [51], which is highly greater than our study. However, the levels of Fe detected from other study are 0.570 mg/kg [50], and 0.352 mg/kg [52], lower than the results found in our study. Besides, the level of Fe was in line with the results of Maria et al. [53], where the range of Fe reported was 0.09–0.9 mg/100 g. The order of the level of Fe in each sample areas are; Arba Minch $>$ Damot Gale > Wolaita Sodo. As the level of metals depicted in this study, Fe was highly accumulated compared with other metals.

In our body, zinc is essential for the proper functioning of the immune system. It facilitates division and growth of cells; wound healing and carbohydrate catabolism [22]. Although Zn is an essential element, its elevated concentration can suppress Cu and Fe absorption and can cause side effects (FAO/WHO, 2011) [14]. The concentrations of Zn in mango fruit samples in Arba Minch, Wolaita Sodo, and Damot Gale were 0.321, 0.251, 0.134 mg/kg respectively Table 4. Based on the recorded mean values, the level of Zn in our sample was 0.235 mg/kg, in strong agreement with the values 0.235 mg/kg conducted by Naresh et al. [50]. Zn levels in the literature investigated as maximum from 33.48 to 40.13 mg/kg [12], 3.40–5.13 mg/kg [51], 0.625 mg/kg [52], and 0.06–0.15 mg/100 g [53]. All values of Zn showed significant difference (p $<$ 0.05) between samples. The safe limit of Zn in fruit consumption is 0.32 mg/kg approved by WHO, which is greater than our Zn values.

Manganes is an essential trace element which act as antioxidant and play important role in the metabolism of carbohydrate, Protein and cholesterol processing [27]. The average level of Mn in mango fruit samples were from 0.121 to 0.239 mg/kg with no significant variations between Wolaita Sodo, and Damot Gale samples (p > 0.05) Table 4. In contrast, the amount of Mn found in Arba Minch (0.239 mg/kg) is greater than the concentration recorded from Wolaita Sodo and Damot Gale (0.173, 0.121 mg/kg) respectively. The amount of Mn in this study was below the results in Nigeria between 2.16 and 2.95 mg/kg [51], and in Pakistan, [27], who estimates 0.6422 mg/L and 0.03–18.2 mg/100 g [53]. Mn concentrations in mango fruit samples were below the recommended level of 0.3 mg/kg proposed by WHO. The level of Mn follows the order as; Damot Gale < Wolaita Sodo < Arba Minch.

Copper is essential for the normal biological activities. It is also involved in hemoglobin synthesis, connective tissue metabolism, and bone development [22]. Copper is one of the most commonly reported adverse health effect of is gastrointestinal problems: nausea, vomiting, and/or abdominal pain, when it is consumed too greater amount [18]. The levels of copper in our studied samples were 0.198, 0.019, 0.165 mg/kg for Arba Minch, Wolaita Sodo, and Damot Gale samples. Concentrations of Cu reported in Nigeria showed from 1.94 to 2.02 mg/kg [12], 2.86–4.79 mg/kg by [51], in Pakistan 0.5466 mg/L [27], 3.185 mg/kg [52], and 0.04–0.32 mg/100 g [53], which is higher than the present study. The levels of Cu indicate significant difference (p $<$ 0.05) among all samples. In this study Table 4, Cu was present in the entire fruits samples below the safe limit 0.2 mg/kg as recommended by WHO/FAO.

The mean levels of Pb and Cd in this study collected from Arba Minch, Wolaita Sodo, and Damot Gale in mango fruit samples were 0.035, 0.097, 0.068 and 0.193 mg/kg respectively. The concentrations of Pb differed significantly (p < 0.05). Lead is known to induce reduced cognitive development and intellectual performance in children and increased blood pressure and cardiovascular disease in adults (Commission of the European Communities, 2002) [49]. The highest level of Pb detected from Wolaita Sodo is 0.097 mg/kg, whereas the minimum value is recorded as 0.035 mg/kg from Arba Minch sample Table 4. The amount of Pb estimated in Nigeria and Bangladesh [12], [51], [54], who calculated the values from 1.24 to 1.78 mg/kg; 15.68–87.89 mg/kg, 1.785 mg/kg, and 1.814 mg/kg [52], were higher than the present study respectively. The level of Pb was similar to the result reported (0.0905 mg/kg) from Pakistan [26]. The results Table 4 signify that the levels of Pb are relatively lower than in most investigated metal samples. The concentration of Pb found in our sample 0.035–0.097 mg/kg, which is below the maximum regulatory limit by WHO.

Cadmium is a trace heavy metal, found as impurity in many products such as Phosphate fertilizers, detergents and petroleum products [27]. The level of Cd determined as 0.193 mg/kg for Damot Gale samples only Table 4. The concentrations of Cd in Arba Minch and Wolaita Sodo samples were not detected because; their concentrations were below the detection limits. The value of Cd in the present study was below reported in Nigeria [51], which are from 0.52 to 1.79 mg/kg, 5.142 mg/kg [52]. However, greater than that of 0.0099 mg/kg and 0.1012–0.1178 mg/L determined in Pakistan [26], [27]. Chinazo et al. [12], investigate comparable Cd level from 0.01 to 0.33 mg/kg. Our calculated results are below the upper permissible safe limit 0.2 mg/kg stated by WHO/FAO. The differences in the level of metals in mango fruit depend on climatic and environmental conditions, soil and water pollution, which can also affect the bioaccumulation rates of metals by plants and their bioavailability and entering the food chain [55].

4.3. Health risk assessment of metals in mango fruit

The estimated daily uptake of trace metals for males and females of our sample is listed Table 5. The estimated daily intake (EDI) values of elements in mango fruit follow the order Fe$>$ Zn $>$ Mn $>$ Cu $>$ Cd (Damot Gale) $>$ Pb, for both males and females. As the comparative analysis of EDI showed, the highest EDI was recorded by Fe 1.31 × 10⁻³ mg/kg/day and 1.22 × 10⁻³ for female and male adults in Arba Minch sample respectively. The minimum EDI was also indicated by Cu 1.56 × 10⁻⁵ mg/kg/day from Wolaita Sodo male adults. In male adults EDI for Fe, Mn, Zn, Cu, Pb, and Cd were analysed from 9.57 × 10⁻⁴ to 1.22 × 10⁻³, 9.9 × 10⁻⁵ to 1.96 × 10⁻⁴, 1.1 × 10⁻⁴ to 2.63 × 10⁻⁴, 1.56 × 10⁻⁵ to 1.63 × 10⁻⁴, 2.87 × 10⁻⁵ to 7.96 × 10⁻⁵ and for female adults, 1.03 × 10⁻³ to1.31 × 10⁻³, 1.07 × 10⁻⁴ to 2.1 × 10⁻⁴, 1.18 × 10⁻⁴ to 2.83 × 10⁻⁴, 1.67 × 10⁻⁵ to 1.75 × 10⁻⁴, 3.08 × 10⁻⁵ to 8.56 × 10⁻⁵ mg/kg/day respectively. According to the earlier report by [56], the value of EDI of Cd ranged from 6.72 × 10⁻⁴ to 1.267 × 10⁻³ mg/kg/day and Pb 8.4 × 10⁻⁴ to1.528 × 10⁻³ mg/kg/day, and Fe, Mn, Cu, and Zn values were 0.095–0.281, 0.008–0.21, 0.0015–0.012, and 0.026–0.421 mg/kg/day [57], higher than the present study.

Table 5.

Evaluated EDI, THQ, HI, CR and TCR of metals in mango fruit samples from Arba Minch, Wolaita Sodo, and Damot Gale.

Risk evaluation	Metal	Arba Minch		Wolaita Sodo		Damot Gale
		Males	Females	Males	Females	Males	Females
EDI	Fe	1.22 × 10−3	1.31 × 10−3	9.57 × 10−4	1.03 × 10−3	1.05 × 10−3	1.13 × 10−3
	Mn	1.96 × 10−4	2.1 × 10−4	1.42 × 10−4	1.53 × 10−4	9.9 × 10−5	1.07 × 10−4
	Zn	2.63 × 10−4	2.83 × 10−4	2.06 × 10−4	2.22 × 10−4	1.1 × 10−4	1.18 × 10−4
	Cu	1.63 × 10−4	1.75 × 10−4	1.56 × 10−5	1.67 × 10−5	1.35 × 10−4	1.46 × 10−4
	Pb	2.87 × 10−5	3.08 × 10−5	7.96 × 10−5	8.56 × 10−5	5.58 × 10−5	6 × 10−5
	Cd	ND	ND	ND	ND	1.58 × 10−4	1.7 × 10−4
THQ	Fe	1.74 × 10−3	1.87 × 10−3	1.37 × 10−3	1.47 × 10−3	1.5 × 10−3	1.62 × 10−3
	Mn	1.4 × 10−3	1.5 × 10−3	1.01 × 10−3	1.09 × 10−3	7.07 × 10−4	7.63 × 10−4
	Zn	8.76 × 10−4	9.43 × 10−4	6.86 × 10−4	7.4 × 10−4	3.67 × 10−4	3.93 × 10−4
	Cu	4.08 × 10−3	4.38 × 10−3	3.9 × 10−4	4.18 × 10−4	3.38 × 10−3	3.65 × 10−3
	Pb	1.44 × 10−3	1.54 × 10−3	3.98 × 10−3	4.28 × 10−3	2.79 × 10−3	3 × 10−3
	Cd	ND	ND	ND	ND	3.16 × 10−1	3.4 × 10−1
HI	$\sum \mathit{THQ}$	9.26 × 10−3	1.02 × 10−2	7.44 × 10−3	7.99 × 10−3	3.24 × 10−1	3.49 × 10−1
CR	Zn	0	0	0	0	0	0
	Pb	2.431 × 0−7	2.62 × 10−7	6.77 × 10−7	7.28 × 10−7	4.74 × 10−7	5.1 × 10−7
	Cd	ND	ND	ND	ND	6.0 × 10−5	6.46 × 10−5
TCR	$\sum \mathit{CR}$	2.43 × 10−7	2.62 × 10−7	6.77 × 10−7	7.28 × 10−7	6.05 × 10−5	6.51 × 10−5

The target hazard quotient (THQ) through consumption of fruits is an actual degree of chemical pollutants. It cannot calculate the exact risk but specifies a level of an alarm condition [58]. In the current study the amount of THQ in all metals were < 1, which indicates the metal uptake via consumption of mango fruits, have no health risks in the study areas for adult population. The maximum value of THQ obtained from Cd 3.16 × 10⁻¹ and 3.4 × 10⁻¹ Damot Gale samples for male and female adults respectively. The minimum THQ value calculated in Zn (3.67 ×10⁻⁴) from male adults in Damot Gale. According to the values Table 5, the THQ amounts for Cd and Pb were below from literature report in Egypt by [56], who estimates for Cd from 0.672432 to 1.267432 and for Pb 0.20988–0.382063. Hazard index (HI) of trace metals in this study were determined from 7.44 × 10⁻³ to 3.49 × 10⁻¹ indicates $<$ 1 which can be the acceptable level of non-carcinogenic adverse health effect on human health. The amounts of HI obtained from present study were lower than the reports from 0.912073 to 1.644178 in Egypt [56].

According to the guidelines stated by New York state Department of health center for environmental health [40], [59], the TCR range is explained as if TCR $\le$ 1 × 10⁻⁶ is low; 1 × 10⁻⁴-1 × 10⁻³ is moderate; 1 × 10⁻³-1 × 10⁻¹ is high, and $\ge$ 1 × 10⁻¹ is very high. The results of CR and TCR were summarized Table 5. The risk values greater than 1 × 10⁻⁴ considered as intolerable, below 1 × 10⁻⁶ have no health effects, and between 1 × 10⁻⁴ and 1 × 10⁻⁶ are considered as in the safe range [40]. Except Damot Gale samples, the TCR values for adult population from all study sites were investigated in the range between 2.431 × 0⁻⁷ to 7.28 × 10⁻⁷, which is less than 1 × 10⁻⁶, it signifies that in low cancer risk, and it is considered as safe, however the values from Damot Gale were estimated as 6.05 × 10⁻⁵ (male) and 6.51 × 10⁻⁵ (female), indicates with in moderate range.

5. Conclusion

Based on our findings, most quality attributes clearly showed significant variations within mango fruit samples collected in different areas. The present study indicates that except chromium from all study areas and Cd in Arba Minch and Wolaita Sodo, the metals are present in mango fruit samples at concentrations levels above for Fe and below for Mn, Cu, Zn, and Pb from the maximum guidelines set by WHO. The decreasing order of the concentrations of trace metals in mango fruit samples was found to be Fe $>$ Zn $>$ Mn $>$ Cu $>$ Cd $>$ Pb. The level of Cr is not detected in our study, because its concentration is below the detection limit. On the basis of our finding, the amount of THQ and HI for Mn, Cu, Zn, Fe, Cd, and Pb in mango fruits, did not generate non-carcinogenic health risk. The cancer risk (CR) level depicts that the uptake of mango fruit has no adverse effects on human health. However, the TCR level of Cd was lying in the moderate range in both male and female adults studied from Damote Gale. According to our findings, the consumption of mango fruit in all study areas did not contribute any health risk. The findings of this study will provide perceptions on metal contamination in mango fruit, which is helpful for regulatory bodies and government professionals in preventive approach to minimize heavy metal pollution due to consumption of mango fruit and also useful for comparison of qualities between mango producing areas worldwide. Further researches on the source of fruit heavy metals are of great significance for controlling metal pollution in mango fruit.

Funding

This practical works were performed at Arba Minch University and we thank the University for materials and tools support. This work was not financially supported.

CRediT authorship contribution statement

Dessie Ezez: conceived the ideas, designed experiments, performed practical work, analysed and interpret the data, wrote the paper. Mitiku Belew: performed the experiments, analysed and interpret the data, contributed materials, reagents and tools.

Statement of Authorship

This statement acknowledges that each undersigned author has made a substantial contribution to the manuscript and is willing to take public responsibility for its contents. Authors attest that all persons designated as authors qualify for authorship and all those who qualify are listed. The corresponding author takes responsibility for the integrity of the work as a whole, from inception to published article. “Author’s credit should be based on 1) substantial contribution to conception and design, or acquisition of data, or analysis and interpretation of data; 2) drafting the article or revising it critically for important intellectual content; and 3) final approval of the version to be published. Authors should meet conditions 1, 2, and 3″.

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Upon publication, authors agree that Analysis of physicochemical attributes, contamination level of trace metals and assessment of health risk in mango fruits from Southern region Ethiopia is the copyright owner of the material published in the Toxicology Reports. However, in accordance with Bethesda statement on Open Access Publishing, all works published in the Toxicology Reports is open access and are available to anyone on the web site of the journal without cost. The users are free to use the work, subject to proper attribution of authorship and ownership of the rights. Authors may use their material in presentations and subsequent publications they write or edit themselves, provided that the Toxicology Report is referenced in writing and is acknowledged as the original publication.

Conflict of Interest and Financial supports

Authors warrant that no any financial interests, direct or indirect, that exist or may be perceived to exist for individual contributors in connection with this manuscript have been disclosed. Furthermore, conflict of interest and sources of financial support of the project are not named in the covering letter as well as the acknowledgments.

Previous publications

Authors certify that neither this manuscript nor one with substantially similar content under their authorship has been published or being considered for publication elsewhere in any language, except described in the covering letter.

Declaration of Competing Interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Dessie Ezez reports equipment, drugs, or supplies was provided by Arba Minch University. Dessie Ezez reports a relationship with Arba Minch University that includes: employment. Dessie Ezez has patent #2o pending to Dessie. The co author who is previously employed by Arba Minch University and me have no any conflict of interest.

Handling Editor: Prof. L.H. Lash

Data availability

The data that has been used is confidential.