Effect of Heavy Metal Content of some Common Spices Available in Local Markets in Erbil City on Human Consumption

Herbs and spices are sources of many bioactive compounds that can improve the taste of foods as well as their influence on digestion and metabolism processes. They can also contain some undesirable components that can be harmful, e.g. micotoxins, pesticides, heavy metals, and polycyclic carbohydrates residues. The objective of this study was to determine metals content in the most popular spices and herbs used in local market in Erbil. The content of these metals was assayed by Atomic absorption spectrophotometric method. The study showed differences in metal concentration according to the plant part (Rhizomes, Seed, Leaf, and fruit). The concentration ranged on dry basis were : ( 6.147.0), (56-650), (6-44), (10.5-22.5), (8.526.5), (26-88.6), (1.25-14.6), and (0.045-1.35) mg/kg for the metals, Zn, Fe, Cu, Cr, Co, Mn, Pb, and Cd respectively. Most of the metal levels in the spices were acceptable with the exception of Pb, Cu and Cd which were above the standard limit approved by World Health Organization (WHO) and Food Agriculture Organization (FAO), Pb was above the standard level for fenugreek, cinnamon, Cd was above the standard level for ginger. Consumers of these spices would not be exposed to any risk associated with the daily in take of 10g of spices per day containing the following metals; Zn, Fe, Cu, Cr, Co, Mn.but there are danger from fenugreek and cinnamon for Pb, while the danger of ginger is from Cd. Generally most of the spices available in the market are safe for human consumption except for Pb and Cd.


INTRODUCTION
In the last three decades, mainly because of their medicinal values, the use of spices and other herbs has increased markedly in most regions of the world, including Europe and North America.For instance, during this period, herbal medication in the USA has grown into an industry worth an average of 5billion per year, with projected annual growth of 15 % ( Abebe, 2006).
Many common spices have outstanding antimicrobial effects.On the other hand, the process of preparation and handling can make them a source of food poisoning (Sherman and Billing, 1998).With the current emphasis on eating more healthy diets that are low in fat and salt, people are turning to various herbs and spices to flavor their food.The culinary herbs and spices that are used to enhance the flavor of vegetables, soups, stir-fry, and pasta dishes can be derived from the bark, buds, flowers, leaves, fruits, seeds, rhizome, or roots of a plant (Wahid et al., 1989).The presence of essential metals like iron, copper, manganese and zinc are very useful for the healthy growth of the body though very high levels are in tolerable, while metals like lead, cadmium etc are toxic at very low concentrations.
The addition of spices that may be contaminated the food as that may result in accumulation of these metals in human organs and lead to different health troubles (Al-Ed et al., 1997) these metals may reach and contaminate plants, vegetables, fruits and canned foods through air, water and soil during industrial processing and packaging (Ozores et al., 1997).The study of these heavy metals is crucial because they have potential hazardous effect, not only on compounds but human health as well.This is due to their cumulative behavior and toxicity although they are generally present in agricultural soils at low levels contamination (Ozkutlu et al., 2006).Monitoring the levels of heavy metal toxicity in spices would help ascertain the health impact of taking these spices, and provide relevant data on spices in the country.
Thus several studies were done to determine the concentration of heavy metals in spices, dry fruits and plant nuts (Gilbert, 1984;Husain et al., 1995) and to study their dang erous effect.
Kurdistan region imports spices among a lot of food stuffs from several countries.These spices may be subjected to contamination by so many ways as mentioned above, however, there is little information available about the safety of these spices with respect to heavy metals.
The main objective of this study was to determine the content of some heavy metals (Zn, Fe, Cu, Cr, Co, Mn, Pd, and Cd) as available in local market of Erbil city in Kurdistan region.

Sampling and Classification
Samples of common spices were collected from the local markets and divided according to the used part of the plant, their scientific, and local names are shown in (Table 1).Samples were kept in polythene bags and kept in a cool dry cardboard prior to analysis.

Experimental Procedures
Samples were cleaned and oven-dried at 80 °C for ≈ 12 hrs before chemical analysis.The dried samples were ground in a mortar with pestle till, a fine powder was obtained.The powder was sieved with a 0.5 mm mesh and kept dry for analysis.
For determination of heavy metal concentrations, a wet digestion of the dried samples was done according to the method described by Jones and Case (1990) using mixture of concentrated H 2 SO 4 and 30% H 2 O 2 .To a 0.5 g of dry-ground sample was added 3.5 ml of 30 % H 2 O 2 and 2 ml of H 2 SO 4 .The mixture was heated to 100 °C, and the temperature was gradually increased to 250 °C, and left at this temperature for 30 min then cooled and an additional 1 ml of 30 % H 2 O 2 (v/v) was added, the mixture were reheated.The digestion process was repeated more than one time until a clear solution was obtained (Kalra, 1998).The clear solution was transferred into a 25 ml volumetric flask, and completed to the mark with double distilled water.A blank digestion solution was made for comparison, containing 3.5 ml of 30% H 2 O 2 (v/v) and 2 ml of concentrated H 2 SO 4 , the solution transferred into 25 ml volumetric flask and completed to the mark with double distilled water.Calibration standards were prepared by dilution of the high purity commercial metal standard for atomic absorption analysis, metal measurement was performed with ( Pye unicam SP9) Atomic Absorption Spectrophotometer, double beam and deuterium background correction.Measurement were done against metal standard solution.

RESULTS AND DISCUSSION
Essential metal (Zn, Fe, Cu, Cr, Co, Mn) and Heavy metal (Pb and Cd) analyses have been performed on 12 local spices and the outcome has been presented in (Table 2).The Values of metal concentration were compared with maximum permissible standard concentration of 50, 300, 20, 30, 50, 100, 10, 0.2 mg/kg respectively as recommended by WHO 2005.
The WHO limit of Zinc is not to be exceeded 50 mg/kg.However, the range of zinc was 6.1 mg/kg for fenugreek to 47.0 mg/kg for black seed ( Fig. 1).It was very well below the limit and may be considered tolerable.A study in Nigeria on food however was showed relatively low levels of zinc 0.06 -56.9 mg/kg (Oninwa et al., 2001).Iron has a relatively high WHO level in foods.As revealed by analytical results (Table 2) iron content of spices samples ranged between 56.0 mg/kg for cardamom and 650 mg/kg for mint (Fig. 2).Although there was a high content of iron in all the samples.Iron intake from spices has no effect on health.Copper content of spices samples ranged between 6.0 mg/kg for cinnamon to 44mg/kg, for sumac and Omani lime (Fig. 3).The Daily intake was much less than maximum permission limit.Copper intake from spices has no effect on health if it is taken in trace amount but can be toxic in high level.In case of chromium highest mean concentration was found for mint leaf 22.5 mg/kg and lowest was for black seed, sumac 10.5mg/kg (Fig. 4).Chromium particularly Cr (III) plays an important role in the body function in trace amount but it is toxic in excess amount.Daily intake values were less than the maximum permission limit values and it is not a bright line for health risk.In case of cobalt there was varied level in concentration for all samples ranging from 8.5mg/kg for fenugreek to 26.2mg/kg for coriander (Fig. 5).Daily intake values were found to be much lower than maximum permission level values so there is no effect on health due to cobalt intake, from spices.Although cobalt is toxic at elevated levels, however the body needs small amount of cobalt in the form of vitamin B12 which is in active physiological form (Weir et al., 1999).In case of Manganese there was small variation in concentration for all the samples ranging from 26.0 mg/kg for sumac and 88.6mg/kg for ginger (Fig. 6).Daily intake were found lower than maximum permission level value.Lead content in cinnamon and fenugreek have levels of 11.7 and 14.6 mg/kg respectively, which are marginally above the WHO limit of 10 mg/kg (Fig. 7).The relatively high levels of lead might have resulted from accumulation of lead through air pollution, inclusion or absorption at the mill during grinding, and from some pesticides, such as lead arsenates, applied during cultivation.It means intake of spices under this study can cause lead accumulation in body.It has been reported to competitively inhibit lead uptake in cells (Loum et al., 1991).Lead is a heavy metal poison which forms complexes with oxo-groups in enzymes to affect virtually all steps in the processes of heamoglobin synthesis and porphyrin metabolism (Ademorati, 1996).Toxic levels of lead in man have been associated with encephalopathy seizures and mental retardation (Schumann, 1990).

Fig.7 : Levels of lead in different spices
There was a little variation in case of cadmium.The concentration ranged between 0.012mg/kg for turmeric to 1.3mg/kg, for ginger (Fig. 8).The maximum permissible limit concentration (0.2 mg.kg -1 ) of cadmium is referred by (FAO/WHO 1984).The high level of cadmium might be due to the use of cadmium-containing fertilizers or from the practice of growing this plant with sewage sludge or both, these result may agree with what reported by (Chizzola et al., 2003).

CONCLUSION
The content of toxic metals in plant spices was generally found to be low, the analyzed sample was shown to be elevated in lead and cadmium respectively.
The highest content of lead and cadmium was shown in fenugreek, ginger and cinnamon.The contents of zinc ,chromium, cobalt, and manganese in spices was relatively low and met the appropriate safety standard and was high at some range for iron and copper which has no effect on the health On the basis of results it can be concluded that the majority of the spices used in the Erbil are not contaminated with heavy metals except a few cases of cinnamon, ginger and fenugreek .Excessive use of these could therefore pose a health hazard to consumers.

Fig. 1 :
Fig. 1 : Levels of Zn in different spices Fig. 2 : Levels of Iron in different spices Fig. 3: Levels of cupper in different spices

Fig. 4 :
Fig. 4 : Levels of chromium present in different spices