Heavy metal levels in selected leafy vegetables obtained from Local market of Dharmjaigarh, Chhattisgarh, India

 

Milan Hait*, Ashutosh Patel, Champa Singh Rajput

Dept. of Chemistry, Dr. C.V. Raman University, Kargi Road, Kota, Bilaspur, C.G.-495113.

*Corresponding Author E-mail: haitmilan@gmail.com

 

ABSTRACT:

The heavy metal levels as micronutrients like Iron (Fe), copper (Cu) and Zinc (Zn) were determined using Digital spectrometer in three different samples of leafy vegetables, purchased from Dharmjaygarh market in Raigarh district of Chhattisgarh. The maximum concentration of Fe, Cu and Zn were found 22.14 mg/kg, 0.72 mg/kg and 6.3 mg/kg in Palak Bhaji, Lal Bhaji and Palak Bhaji respectively. The minimum concentration of Fe, Cu and Zn were found 6.23 mg/kg, 0.21 mg/kg and 1.52 mg/kg. The relative abundance of metals in leafy vegetables followed the sequence Cu (0.52 mg/kg) < Zn (4.33 mg/kg) < Fe (15.58 mg/kg). The levels of Fe, Cu and Zn were below the FAO/WHO recommended limits for metals in vegetables. Low concentrations of Cu, Fe and Zn in all the samples are indications that these plants contribute no toxic effects of metals. The results showed that, these vegetables are the main sources of essential trace elements. The daily human intakes of metals have also been calculated which were observed below recommended values by the FAO/WHO.

 

KEYWORDS: Heavy metals, Micronutrients, Leafy vegetable, Local market, Analysis and Public Health.

 

 

INTRODUCTION:

Plant form the basis of most food chain on the planate. Vegetables are an essential constituent of human beings and animal diet that contains important nutrients and trace elements. They are very significant protective food and useful for the maintenance of health and the prevention and treatment of various diseases. Vegetables are rich sources of vitamins, fibers, and minerals, and also have beneficial anti-oxidative effects1-3.

 

Leafy vegetables have greater potential of accumulating heavy metals in their edible parts than grain or fruit crops. Studies on the uptake of heavy metals by plants have shown that heavy metals can be transported passively from roots to shoots through the xylem vessels4-5.

 

Vegetables takes up metals by absorbing them from contaminated soils, as well as from deposits on different parts of the vegetables exposed to the air from polluted environments. The essential metals can also produce toxic effects when the metal intake is excessively elevated. However, intake of heavy metal contaminated vegetables may pose a direct threat to human health. This is because, heavy metals have the ability to accumulate in living organisms and at elevated levels they can be toxic6-7.

 

Environmental pollution has caused the contamination of soils, on the other hand waste water irrigation results in the significant mixing of heavy metal content of the agricultural land. Crops and vegetables grown in soils contaminated with heavy metals have greater accumulation of heavy metals than those grown in uncontaminated soils. Heavy metals that are tolerated by plants and are toxic to humans and animals are easily transferred to consumers through food supply and consequently cause health problems8-9. It is necessary to assess the levels of heavy metals in edible vegetable and to report possible contamination that would represent a health hazard. The main aim of this research work was to determine the concentration of heavy metals in different green leafy vegetables collected from the local market of Dharmjaigarh city in Raigarh district of Chhattisgarh and to compare safety level of heavy metals in those vegetables what was recommended by the international organization.

 

MATERIAL AND METHODS:

The entire chemicals used in the analysis were Chemicals of analytical grade procured from E marks, Germany, Qualigens, Mumbai India and Loba Cheme of high purity and distilled deionized water were used in all the solution preparation. All glass wares and plastic containers used were washed with detergent solution followed by (20% v/v) nitric acid and then rinsed with tap water and finally with distilled deionized water. Also, standard solutions of the metal salts and other reagents were prepared.

Study area:

The study area covered in this research was Dharmjaigarh Market of Raigarh district in the state of Chhattisgarh, India. Dharmjaigarh is a prominent town and a taluk headquarters in Raigarh District. It is located on Raigarh Ambikapur highway, about 77 km northwest of Raigarh. Dharmjaigarh is located at 22.47°N to 83.22°E. It has an average elevation of 300 m (980 ft)with a population less than twenty thousands10-12.

 

Sample and sampling:

We have selected three different sample of leafy vegetables namely, Mooli Bhaji (Raphanus Sativus L.), Spinach (Spinaceao leracea L.) and Lal Bhaji (Amaranthus tricolour L.). The vegetable samples were collected from Dharamjaygarh market in the month of March’ 2017. The details of these vegetables are given in the Table1.

 

Table 1 : Specification of  Leafy Vegetable13

S.N.

Common Name

Vernacular Name

Botanical Name

Family

Habit

Ethnobotanically

important plant part

1

Mooli Bhaji

Raddish

Raphanus sativus L.

Brassicaceae

Cultivated

Leaves and root

2

Palak Bhaji

Spinach

Spinaceao leracea L.

Chenopodiaceae

Cultivated

Leaves

3

Lal Bhaji

Red Spinach

Amaranthus tricolour L.

Amaranthaceae

Cultivated

Leaves and stem

 

Sample treatment:

The vegetables were washed with fresh tap water and then rinsed with distilled deionized water. These samples were cut into pieces with knife and were air-dried in the laboratory for 4 days before oven-dried at 105°C for about 24 h. The samples were crushed into powder in a mortar with a pestle. The samples were then sieved through a 2 mm nylon sieve and transfer into a labeled polyethylene container for analysis14-15.

 

Sample digestion:

1gm vegetable samples were digested after adding 20ml conc.  HNO3, 2 ml HClO4 and HCl (10:1), left for 10 minutes and digest at 70 to 80°C on hot plate. The solution was allowed to evaporate to dryness until all the tissue had been digested and raised the temperature 105oC to reduce the volume to 0.5-1.0 ml and add 10 ml of distilled water, boil the residues. The mixture was cooled and filtered through a Whatman no. 541 filter paper into a 100 ml volumetric flask and made up to mark with distilled deionized water14-15.

 

Sample analysis:

A serial dilution method was used to prepare the working standards and the concentrations of the metals in each sample digest were determined using Digital spectrophotometer (Systronic, Model No.118) by preparing standard curve. Fe, Cu and Zinc were determined spectrophotometrically by 1,10 phenonthroline method, Neocuproine method and dithiazone method at 510 nm, 457 nm and 620 nm respectively16.

 

Daily intake of heavy metals from vegetables

The daily intake of heavy metals through the consumption of vegetables tested was calculated according to the equation17:

 

Daily intake of metals (DIM) = DVC × VMC

DVC = daily vegetable consumption; VMC = mean vegetable metal concentrations (mg/day, fresh weight).

Where daily vegetable consumption was taken as 98 g of vegetables per person per day as set by the FAO/WHO (1999), for heavy metal intake based on body weight for an average adult (60 kg body weight)18.

 

RESULT AND DISCUSSION:

The experimental results of the metal contents obtained from each leafy vegetable from the Dharmjaigarh market site are listed in Table 1 and graphical representation are shown in Fig 2. The Fe concentrations in different leafy vegetables like Mooli Bhaji, Palak Bhaji and Lal Bhaji were calculated 6.23 mg/kg, 22.14mg/kg and 18.36 mg/kg respectively. The concentrations of Cu in Mooli Bhaji, Palak Bhaji and Lal Bhaji were calculated 0.21 mg/kg, 0.64 mg/kg and 0.72 mg/kg respectively. The concentrations of Zn were estimated 1.52 mg/kg, 6.3 mg/kg and 5.18 mg/kg in Mooli Bhaji, Palak Bhaji and Lal Bhaji respectively.

 

Table 2: Concentration of Fe & Zn in Leafy Vegetables ( mg/kg)

S.N.

Sample/ Metal Concn

Mooli Bhaji

Palak Baji

LalBhaji

FAO/WHO Safe Limit

1

Fe

6.23

22.14

18.36

425

2

Cu

0.21

0.64

0.72

40

2

Zn

1.52

6.3

5.18

99.4

 

Table 3:  Daily intake of Heavy metal (DIM) through consumption of vegetables

S.N.

Heavy metal

Mean Metal Concn (mg/kg)

Daily intake (μg/day)

FAO/WHO Limit or PTDI Limit

1

Fe

15.58

1526.51

48 mg

2

Cu

0.52

51.29

3 mg

3

Zn

4.33

424.67

60 mg

 

 

Fe has several functions in the body. It serves as a carrier of oxygen by haemoglobin from the lungs to the tissues, as a transport medium for electrons within cells, and as an integrated part of important enzyme systems in various tissues. Fe is essential for the synthesis of chlorophyll and activates a number of respiratory enzymes in plants19. The highest amount of Fe is found in Palak Bhaji 22.14 mg/kg and the lowest amount of Fe was found in Mooli Bhaji 6.23 mg/kg. The Fe concentrations of were found among the vegetables in the order of Palak Bhji>Lal Bhaji >Mooli Bhaji. The Fe contents of these plants are lower than the FAO/WHO (2001)20 safe limit of 425.00 mg/kg. These vegetables could be good supplement for Fe.

 

Cu is an essential metal for plant growth and activation of many enzymes, however most plants contain the amount of copper which is inadequate for normal growth that is usually ensured through artificial or organic fertilizer21. The highest concentration of Cu, 0.72 mg/kg in Lal Bhaji and the least concentration of Cu, 0.21 mg/kg were recorded in the Mooli Bhaji. The Cu concentrations of were found among the vegetables in the order of Lal Bhaji > Palak Bhji> Mooli Bhaji. The contents of Cu recorded in this study are lower than the permissible level by FAO/WHO in the leafy vegetable.

 

Zn is the least toxic and an essential element in human diet. It is distributed widely in plant and animal tissues and occurs in all living cells. It functions as a cofactor and is a constituent of many enzymes. The recommended dietary allowance for Zn is 15 mg/day for men and 12 mg/day for women by Agency for Toxic Substances and Disease Registry22-23. The highest amount of Zn was found in Palak Bhaji6.3 mg/kg and the lowest amount of Zn was found in Karmota Bhaji 1.52 mg/kg. The concentrations of Zn is found in the order of Palak Bhaji>Lal Bhaji>Mooli Bhaji. The contents of Zn in all the plants examined are generally lower than the permissible levels by the FAO/WHO (2001)20 in leafy vegetables as shown in Table 2. Regular consumption of these vegetables may assist in preventing the adverse effect of zinc deficiency which results in retarded growth and delayed sexual maturation24.

 

Fig. 2: Concentrations of metals in Leafy vegetables

 

 

The exposure of consumers and the related health risks are usually expressed in terms of the provisional tolerable daily intake. The FAO/WHO (1999)18 have set a limit for the heavy metal intake based on the body weight for an average adult, namely, 60 kg body weight. The average diet per person per day of vegetables is 98 g. If the mean levels of Fe (15.58 mg/kg), Cu (0.52 mg/kg) and Zn (4.33 mg/kg) found here are consumed daily, the contribution of heavy metal intake for an average human being from the vegetable diets were calculated and presented as shown in Table 3. The estimated daily intakes for heavy metals are reported by the FAO/WHO, which had set a PTDI limit for heavy metal intake based on body weight for an average adult (60 kg body weight) for heavy metals as shown in   Table 3.

 

CONCLUSION:

Fe, Cu and Zn are chief dietary mineral supplements which have special role in important metabolic function in human and animal. The required concentration of Fe in diet for human body is 17 mg, Cu 2-3 mg and Zn 3-4 mg. in a standard body weight. Levels of the metals are found to be within the safe limits prescribed by the FAO/WHO. This is an important result as human health is directly affected by consumption of vegetables as diet. The monitoring of heavy metals in vegetables needs to be continued; because these are the main sources of food for humans and animals which are considered as bio indicators of environmental pollution.

 

ACKNOWLEDGEMENT:

The authors are grateful to HOD, Dr. Manish Upadhyay, Dr. C. V. Raman University, Kota, Bilaspur (C.G.) for providing research facilities.

 

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Received on 15.05.2017         Modified on 03.06.2017

Accepted on 12.06.2017         © AJRC All right reserved

Asian J. Research Chem. 2017; 10(3):354-358.

DOI:   10.5958/0974-4150.2017.00060.8