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Background
Heavy metals have remarkable contribution in different parts of environment as a result of mining, smelting, electroplating, energy and fuel production, power transmission, intensive agriculture, sludge dumping, melting operations and other human activities (1,2). High concentrations of all metals are toxic environmental pollutants (3).
Despite fruit and vegetables are one of the important parts of human diet, the effect of heavy metal contamination of these foodstuffs cannot be survived. Fruits have different beneficial vitamins, minerals, fibers and antioxidant components. Since, consumption of heavy metal-contaminated fruits have serious risk to human body health; contamination of food by heavy metals is among the most important parts of quality assurance of daily food (4,5,6). Biological half-lives of heavy metals is very long, and do not degrade biologically, thus have the potential for accumulation in organs of human, leading to dangerous side effects (7,8). Plants absorb contaminants using airborne, irrigation with polluted water and also by roots from polluted soils (9).
Content of heavy metals in some kinds of vegetables from Turkey were determined by Demirezen and Aksoy (10). The concentrations of some heavy metals have been investigated in different vegetables and fruits of Egyptian markets (4). Fytianos et al. (11) surveyed the levels of some heavy metals in leafy vegetables from Northern Greece, and Sobukola et al. (12) determined the content of heavy metals in fruits and vegetables from Lagos, Nigeria.
Elbagermi et al. (13) evaluated lead, copper, zinc, cobalt, nickel, and cadmium content in some fruits and leafy vegetables of Misurata area of Libya.
Based on probability of heavy metals toxicity, persistence and cumulative property of them and absorption in human daily diet, it is necessary for the survey different items of food with international standards. Maximum recommended content by WHO for Copper, lead, and Arsenic in fruits are 20, 0.3 and 5 mg/kg, respectively (14).
Aims of the study:
Contamination of Cydonia fruit by studied heavy metals from the Hamadan province has not been determined yet; thus, the aim of present study was investigation the content of Pb, Cu, and As in Cydonia fruits from Hamadan province.
 

Materials & Methods

Sampling and analysis of fruits
Nine samples of Cydonia (quince) fruit were bought from local wholesale fruit in Hamadan city in September 2016. Frist 3 samples are belonged to Kurdistan province, second 3 samples are belonged to Esfsahan province and third 3 samples are from Hamadan province. The Genus Cydonia is from the family Rosaceae (which also contains apples and pears, among other fruits) and is one part of consumption fruit of human diets. After washing the quince samples with tap water, 5 g of each sample was placed in a porcelain crucible and ashed in an oven at 500 °C for 24 h. Then ashed material was dissolved in 4 mL concentrated HNO₃ (Merck, Germany), evaporated to dryness, heated again for 4 h to 500 °C, dissolved in 3 mL mixture of concentrated HNO₃ and H₂SO₄ (2:1 v/v), and diluted with deionized water up to 50 mL. Finally, for the As, Cu and Pb analyses, a Varian710-ES inductively coupled plasma-optical emission spectrometry (ICP-OES) was used(15). Dankan test was used for comparison between the average concentration of metals (As, Pb and Cu) in surveying samples and T test was used for one sample to compare the average concentration of above metals with national and international standards. Pearson correlation test was used for determining correlation between metals in vegetable samples. In this research, data were analyzed by SPSS 19.0statistically.  
 

Results

Concentration of measured heavy metals is presented in Table 1.
Table 1) Heavy metal concentrations in sampled fruits

Sample number	Pb	Cu	As
Standard concentratiom	0.3	20	5
1	0.41	0.6	3.8
2	0.63	0.7	4.6
3	0.85	0.8	5.4
4	0.06	0.11	0.6
5	0.10	0.16	0.66
6	0.14	0.21	0.72
7	0.03	0.09	0.8
8	0.03	0.14	0.86
9	0.03	0.19	0.92

 
As shown in table 1, the total levels of lead in the collected samples have been ranged from 0.03 to 0.85 mg/kg with the maximum concentration in sample 3. Copper levels in the collected fruits differed from 0.09 to 0.8 mg/kg with the maximum content in sample 3. Finally arsenic content has been differed from 0.6 to 5.4 mg/kg with the maximum content in sample 3.Statistical results show that the average concentration of copper in all samples are lower than the WHO/FAO standards in all samples. Also the concentrations of Pb in samples 1, 2 and 3 are above recommended levels. The concentration of Arsenic in sample 3 is above standard level.
The Dankan’s test results (different roman letters are presented in each column of table 2) indicate statistical significant differences (P<0.05) in the contents of As, Cu, and Pb between some brands of quince. This means that no significant differences were observed in the content of As, Cu and Pb between quince samples was cultivated in Isfahan and Hamadan Province. However, the significant differences were observed in the content of As, Cu and Pb between quinces samples were cultivated in Kurdistan Province compared with samples from other provinces.
The Pearson's correlations analyses were performed between metal concentrations in quince samples to understand the relationships between them. The results showed that there was positive correlations found between As and Cu (r=0.991, P<0.01), between As and Pb (r=0.987, P<0.01) and between Cu and Pb (r=0.993, P<0.01) (table 2).
 
Table 2) Correlation between the total contents of heavy metals in quince samples.

Elements	As	Cu	Pb
As	1
Cu	0.991	1
Pb	0.987	0.993	1

 
 

Discussion

Although different effects of heavy metals, in high concentrations, in plants have been studied for many years, exposure to these elements continues and even increasing. Crops can absorb these contaminants from contaminated soils and concentrate them in different parts easily. Fruits are important part of human diets. So evaluation of agricultural products is necessary. Comparison of our results with standard levels (FAO/WHO) showed which the average concentrations of copper in all samples are lower than the presented standards by WHO in all samples. This result agrees with the conclusions of Kibria et al and Lin et al (16,17). The levels of As and Pb in sample 3 are above standard. According to Dankan’s test concentration of all measured heavy metals in samples cultivated in Isfahan and Hamadan province are lower than which cultivated in Kurdistan province. The result of Pearson's correlations test showed positive correlations between heavy metals in quince samples. This means that these metals have same origin. This result agrees with the conclusions of Jahangard et al. 2016 (18). Existence of heavy metals in studied samples shows the absorption of these metals can take place from different ways. Thus, information about the intake of heavy metals through the food chain is important in assessing risk of human health.
 

Conclusion

Fruits are among the main sources of essential heavy metals; these are also the way through which we are exposed to various toxic metals. These elements are easily accumulated in the edible parts of the agricultural products so many serious systemic health problems can develop  can result of an excessive accumulation of dietary some elements for example Cd, As and Pb in the human body. This paper investigated the concentration of Pb, Cu, and As in Cydonia fruits in Hamadan province. According to our results using of fertilizer, pesticides and contaminated irrigation water has contributed to the elevation of some metal content in agricultural soils and products significantly. So there is a serious concern about daily food safety resulting environmental contamination.
 

Footnotes

Acknowledgement:
Authors are thankful to the Young Researchers and Elite Club, Hamedan Branch, Islamic Azad University for providing instruments to conduct and complete this study
Conflict of Interest:
The authors declared no conflict of interest.