The levels of the hazardous metals (Pb and Cd) in five different leafy vegetable plant samples ( viz: Hibiscus cannabinus, Cassia tora, Vernonia amygdalina, Corchorus olitorius, and Corchorus tridens) consumed by Kano inhabitants were investigated and found to be at concentration below the environmental lead action level set by US EPA/WHO. Cadmium was not detected in the samples. Low concentration of Pb and absence of Cd in all the plant samples analyzed are clear indication that these may not exhibit toxicity effects due to any of these metals. The consumers are therefore safe from their toxicity effect.Keywords: Lead, Cadmium, Leafy Vegetables, Kano, NigeriaNigerian Journal of Basic and Applied Science (2011), 19(2): 304-30

Mohammed, MI

Sharif, N

English

ABSTRACT: Five different vegetable samples were obtained from Yan-Kaba Market, Kano city, Nigeria, and were analyzed for the presence of Mg, Mn, Cu, Zn, Mo, and Fe using Atomic Absorption Spectrophotometery. The results of the analysis showed that, on the average, highest concentration of Mg was recorded in the range of 0.964 to 1.393mg/g in all the samples analyzed, while Mo was found to be the least with concentration range of 0.014 to 0.031mg/g. Comparing the mineral contents obtained in this work with the Recommended Dietary Allowances (RDAs) values, the results indicate that the vegetables could be good supplement for some of the elements analyzed.Keywords: Leafy Vegetables, Mineral, Trace MetalsNigerian Journal of Basic and Applied Science (2011), 19(2):208-21

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Available online at http://www.ajol.info/index.php/njbas/index  Nigerian Journal of Basic and Applied Science (2011), 19(2):208-212   ISSN 0794-5698  Mineral Composition of Some Leafy Vegetables Consumed in Kano, Nigeria  *M.I. Mohammed and N. Sharif Department of Pure and Industrial Chemistry, Bayero University, P.M.B. 3011, Kano, Nigeria [*Corresponding author. E-mail address: musaimf@yahoo.com; Tel.: +23408033149483]  208  ABSTRACT: Five different vegetable samples were obtained from Yan-Kaba Market, Kano city, Nigeria, and were analyzed for the presence of Mg, Mn, Cu, Zn, Mo, and Fe  using Atomic Absorption Spectrophotometery.  The results of the analysis showed that, on the average, highest concentration of Mg was recorded in the range of 0.964 to 1.393mg/g in all the samples analyzed, while Mo was found to be the least with concentration range of 0.014 to 0.031mg/g. Comparing the mineral contents obtained in this work with the Recommended Dietary Allowances (RDAs) values, the results indicate that the vegetables could be good supplement for some of the elements analyzed.       Keywords: Leafy Vegetables, Mineral, Trace Metals  INTRODUCTION Leafy vegetable are widely used for culinary purposes. They are used to improve the quality of soup and also for their dietary purposes (Sobukola et al., 2007). They are made up of chiefly cellulose, hemi-cellulose and pectin substances that give them their texture and firmness (Sobukola and Dairo, 2007). Fresh vegetables are of great importance in the diet because of the presence of vitamins and mineral elements. They are very important protective food and useful for the maintenance of health and the prevention and treatment of various disease (D’ Mellow. 2003). However, these plants contain both essential and toxic metals over a wide range of concentrations (Radwan and Salama, 2006).   Metals are circulated by biogeochemical processes. Some metals are essential and their deficiency results in impairment of biological functions. When present in excess, essential metals may become toxic. Other metals not known to have essential function may give rise to toxic manifestations when intakes are in excess (Friberg and Norberg, 1986). Unlike organic chemicals that can be eliminated from tissue by metabolic degradation, the metals are not biodegradable and therefore have potential for bioaccumulation (Gbaruko and Friday, 2007).  Accumulation in tissues do not necessarily imply the occurrence of toxic effects because inactive complexes or storage are formed in case of certain metals (Clarkson, 1986).  Heavy metals imputes need not to be as small as possible because some metals are indispensable for life. There are three criteria for determining whether or not an element is essential;  It must have direct influence on the organism and is involved in its metabolism.   The organism can never grow complete in its life cycle without adequate supply of the element, and   The element cannot be wholly replaced by any other (Alloway, 1990).  Copper and Zinc are essential elements whose lack give rise to deficiency problems in plants and animals (Alloway, 1990). Food plants that tolerate high concentration of potentially hazardous metals (phyto-accumulators) create greater health hazard to consumers than those that are more sensitive. In general, food plants are more sensitive to Cu and Zn than to Pb and Cd (Alloway, 1990). Excessive uptake of   both essential (Cu and Zn) and non essential (Pb and Cd) metals may results in adverse effect on soil biota (Alloway, 1990).   The aim of this work is to determine the levels of Cu, Zn, Mg, Mn, Mo, and Fe in leaves of some selected leafy vegetables consumed by the inhabitants of Kano, Nigeria.   MATERIALS AND METHOD Sampling Collection and Preparation Five commonly and widely consumed leafy vegetables in Kano, Nigeria were selected for Nigerian Journal of Basic and Applied Science (2011), 19(2):208-212   209analysis. The varieties are; Hibiscus cannabinus, Cassia tora, Vernonia amygdalina, Corchorus olitorius, and Corchorus tridens. The vegetable were purchased from “Yan-Kaba market in Kano city, Nigeria. Identified in the Department of Biological Sciences, Bayero University Kano-Nigeria.   The leaves were separated in each case, cut into pieces, washed, and air dried on the laboratory benches and later dried in an oven at 800C for six hours. The dried materials were grounded into powder using mortar and pestle. Each powdered sample was digested as reported by Anjorin et al. (2010). Briefly, 2g of each powdered samples was weighed into separate beaker and treated with 20cm3 of HNO3 and digested on an electric hot plate at 70-90oC for 60 min. Blank was prepared similarly by digesting 20cm3 of HNO3 in an empty beaker. The content of the beaker was allowed to cool, filtered through Whatman No. 42 filter paper into volumetric flask and made up to volume of 100cm3 with de-ionized water. The digests were analyzed for the mineral and trace metals contents using Buck Scientific model 210VGP Atomic Absorption Spectrophotometer.  Instrumentation  Metal concentrations were determined on a Buck scientific model 210VGP Atomic Absorption Spectrometer (AAS) equipped with a background correction. The result of each sample represents an average of three replicate readings. A calibration curve of absorbance against concentrations of each element under investigation was constructed and finally the concentration of each element was determined from the calibration curve of its standards by interpolation.  RESULTS AND DISCUSSION  The results of some essential minerals in the vegetables investigated was presented in Figure 1.    Magnesium (Mg) Magnesium is widely distributed in plants and animal foods. Geochemical and other environmental variables rarely have a major influence on its contents in foods. Most green vegetables, legume, seeds, peas, beans and nuts are rich in magnesium, as are some shell fish, spices and Soya flour, all of which usually contain more than 500mg/kg fresh weight. Soft tissue magnesium functions as a co-factor of many enzymes involved in energy metabolism, protein synthesis, RNA and DNA synthesis and maintenance of the electrical potential of nervous tissues and cell membranes. Of particular importance with respect to the pathologic effects of magnesium deficiency is the role of this element in regulating potassium fluxes and its involvement in the metabolism of calcium FAO/WHO, (2002). As shown in the Figure 1, Cochorus olitorius contained the largest amount of magnesium (1.39mg/g) among the plants studied. The magnesium content of the other plants ranged from 0.893 to 1.191mg/g. Various values have been previously reported for vegetables which include 3.80mg/g in C. tridens and 3.968mg/g in C. tora (Barminas et al., 1998). Similarly, Freiberger et al. (1998), reported C. tridens, H. subdarifa and Moringa oleifera to contain 3.85mg/g, 3.52mg/g and 4.34mg/g, respectively. These values are significantly different from those reported in this work. The differences in the mineral content of the vegetable plant might be due to soil compositions and the rate of uptake of minerals by individual plant (Anjorin et al., 2010; Asaolu and Asaolu, 2010).   Manganese (Mn) Manganese among the various plants was found to be concentrated in C. olitorius (0.613mg/g) than all other plants samples, followed by C. tora (0.425mg/g). H. cannabinus was having the least manganese content of 0.275mg/g, compared to V. amyglidina and C. tridens with 0.318 and 0.400mg/g respectively (Figure 1). Various values have been previously reported for leafy vegetables, which include 0.027mg/g of V. amyglidina by Ayoola et al. (2010). Barminas et al. (1998) reported the levels of manganese in C. tora and C. tridens to be 0.048mg/g and 0.074mg/g, respectively. Freiberger et al. (1998) had reported levels of Mn in C. tridens obtained from two different locations to be 0.0497mg/g and 0.0498mg/g. however, the values reported by these workers were less than to those obtained in this study. High concentration of Mn in these plants is not up to the extent that, are likely to cause harm to the individuals consuming them. But rather help them in preventing adverse effects Mohammed and Sharif: Mineral Composition of Some Leafy Vegetables Consumed In Kano……   210of dietary deficiencies of manganese on the central nervous systems and skeletal anomalies among children (Barminas et al., 1998). According to Itanna (2002), when people do not live up to the recommended daily allowance their health decrease, but when the uptake is too high health problems also occur. The recommended daily allowance for Mn is 2.5 to 5.0mg (FAO/WHO, 2002).       Figure 1: Mean concentrations of Fe, Cu, Zn, Mn, Mo, and Mg in leaves of samples analyzed   Key: VAR= Vernonia  amygdalina, CTO= Cassia tora, COL =Corchorus  olitorius,      ,           HCA= Hibiscus cannabinus. CTR= Chorchorus tridens  Iron (Fe) Iron is important in the diet especially for pregnant and nursing mothers as well as infants. It is also needed by the convalescent and the elderly to reduce cases of diseases associated with deficiency of iron such as anemia (D’Mello, 2003). The highest iron content of 0.334mg/g was found in the leaves of C. olitorius. According to Figure 1, the leaves of C. tridens contain the least iron content of 0.213mg/g, while V. amyglidina and H. cannabinus have significantly higher iron content of 0.260 and 0.250mg/g, respectively. V. amyglidina, C. tora and C. olitorius leaves were reported to contain 0.277mg/g and 0.204mg/g and 0.84mg/g of iron respectively by Ayoola et al. (2010), Barminas et al. (1998) and Asaolu and Asaolu, (2010). Freiberger et al. (1998) reported the iron content of C. tridens obtained from two regions in Niger republic to be 0.385mg/g and 0.405mg/g. The values are in agreement with those obtained in this work. According to research carried out by Barminas et al. (1998), an average culinary preparation contains about 300g of the fresh leaves of vegetables and this would result in an intake of 30g dry weight leaves per serving portion. Therefore 0.33mg/g, 0.260mg/g and 0.250mg/g in C. olitorius, V.  amygdalina and H. cannabinus, will contribute up to 9.9mg, 7.8mg and 7.5mg/serving portion of Fe respectively, to the recommended dietary allowance of Fe (10-15mg/day) (FAO/WHO, 2002).  Copper (Cu) Copper is an essential micronutrient which functions as a biocatalysts, required for body pigmentation in addition to iron, maintain a healthy central nervous system, prevent anemia and interrelated with functions of Zn and Fe in the body (Akinyele and Osibenjo, 1982). However, most plants contain the amount of copper which is inadequate for normal growth which is usually ensured through artificial and organic fertilizers (Itanna, 2002). In this study the concentrations of Cu in the analyzed samples varied between 0.633 and 0.333mg/g with C. tridens leaves having the highest and C. tora the least copper concentrations 00.20.40.60.811.21.41.6VAR CTO CTR COL HCAFe Cu Zn Mn Mo Mgconcentrationmg/gNigerian Journal of Basic and Applied Science (2011), 19(2):208-212   211as shown in Figure 1. The values obtained in this work were observed to be higher compared to other published results such as reported by Barminas et al. (1998), as C. tora and C. tridens which have 0.018mg/g and 0.015mg/g of copper, respectively. The difference in copper level could be due to the fact that many soils are geographically deficient in certain minerals and therefore foods plants grown in them lack those nutrients. A similar problem can be caused by over farming or poor soil management (Nielson, 1996).   Zinc (Zn) Figure 1 shows the trace and mineral composition of five leafy vegetables widely consumed by people of Kano Nigeria. From the figure it can be seen that C. tridens contained the highest amount of zinc (0.375mg/g) followed by V. amyglidina (0.318mg/g), while 0.250mg/g, 0.228mg/g and 0.221mg/g were found in H. Canabinus, C. tora and C. olitorius respectively. The zinc content of C. tora (0.228mg/g) was not significantly different from that obtained in a published work of Barminas et al., 1998), which reported C. tora to contain an average of 0.209mg/g Zn. They also reported C. tridens, Amarantus spinosus, Adansonia digitata to contain 0.123, 0.068 and 0.224mg/g of Zinc, respectively. Zinc is important for nerve function and male fertility. It is important for normal sexual development especially for the development of testes and ovaries, it is also essential for reproduction (Ayoola et al., 2010), healthy functioning of the heart and normal growth (Elizabeth, 1994). Regular consumption of these three vegetables may assist in preventing the adverse effect of zinc deficiency which results in retarded growth and delayed sexual maturation because of its role in nucleic acid metabolism and protein synthesis (Barminas et al., 1998).  Molybdenum (Mo) The content of molybdenum in the plant samples analyzed ranges from 0.014mg/g to 0.031mg/g (Figure 1) in the V. amyglidina and H. cannabinus respectively while C. tora (0.024mg/g), C. olitorius (0.027mg/g) and C. tridens (0.022mg/g) have the intermediate levels. No much work was found for the composition of Mo in various plants. However, Freiberger et al. (1998) reported low Mo concentration (<0.005mg/g) on C. tridens, Ammarantus viridus (0.0075mg/g), Ximenia americana (0.063mg/g), M. oleifera (0.00745mg/g) and Maerua crassifolia  (0.022mg/g). The recommended daily allowance for Mo ranges from 0.075 to 0.250mg/g (Nielson, 1996).   CONCLUSION This study reported the concentrations of some trace elements and mineral composition of five different vegetable plants consumed by the Kano inhabitants; the results show that the plants are rich sources of minerals and beneficial trace elements.  The findings have indicated that the vegetables studied could make significant contribution to the recommended dietary allowances for the nutrients. There is need to investigate the proximate composition of these vegetable in order to have a complete picture of their nutritional value.  REFERENCES Akinyele, I.O. and Osibanjo O. (1982). Levels of Trace Elements in Hospital Diet. Food Chemistry 8: 247-251. Alloway, B.J. (1990), Heavy metals in soil, Blackie, revised edition, Glasgow, PP. 189-204.  Anjorin, T.S., Ikokoh, P. and Okolona, S. (2010). Mineral Composition of Moringa  Oleifera leaves, Pods, and  seed from two region in Abuja, Nigeria. International  Journal of Agriculture and Boilogy, 12: 431 – 434. Anyoola, P.B., Adeyeye A. and Onawumi O.O. (2010). Trace Element and Major Evaluation of Spondias mombin, Vernonia Anygdalina and Momordica Charantia Leaves, Pakistan Journal of Nutrition 9(8): 755-758. Asaolu S.S. and Asaolu, M.F., (2010). Trace Metal Distribution in Nigerian Leafy Vegetables. Pakistan Journal of Nutrition 9(1): 91-92. Barminas, J.T., Charles, M. and Emmanuel, D. (1998). Mineral Composition of Non-conventional Leafy Vegetables, Plant Foods for Human Nutrition 53: 29-36. Clarkson, T.W. (1986). Effect-General Principles Underlying the Toxic Action of Metals. In Hand Book on the Toxicology of Metals Vol. Mohammed and Sharif: Mineral Composition of Some Leafy Vegetables Consumed In Kano……   2121 General Aspect edited by Friberg, G.F Nordberg and V.B Vouk. Pp 128-148.  D’Mello, J.P.F. (2003). Food Safety, Contamination and Toxins, CABI publishing, Wallingford, Oxon, UK, Cambridge, MA, P. 480. Elizabeth, K. (1994). Immense Help from Nature’s Workshop. 1st Ed. Elikaf Health Services Ltd., pp: 207-209. Freiberger, C.E., Vanderjagt, D.J., Pastuszyn, A., Glew, R.S., Mounkaila, G., Millson, M. and Glew, R.H. (1998). Nutrient Content of the Edible Leaves of Seven wild Plants From Niger. Plant Foods for Human Nutrition 53: 57-69. Friberg, L. and Norberg, G.E. (1986). Introduction. In Handbook on toxicology of metals Vol.1; General Aspects, edited by Friberg, L and Nordberg, GE, Vouk, V.B Amsterdam; Elseivier science, Publishers B.V, PP. 1-3. Gbarako, B.C. and Friday, O.U. (2007). Bioaccumulation of Heavy metals of some fauna and flora. International Journal of Environmental Science and Technology 4(2): 197-202. Itanna, F. (2002). Metals in Leafy Vegetables Grown in Addis-ababa and Toxicology Implications. Ethiopian Journal of Health Development. 16: 295-302. Nielson, F.H. (1996). Other Trace Elements in Present Knowledge of Nutrition. 7th edition, International life Science Institute Press, Washington D.C.; pp 353-377. Radwan, M.A., Salama, A.K. (2006). Market Basket Survey for Some Heavy Metals in Egyptian Fruits and vegetables. Food Chemistry and Toxicology 44: 1273-1278.   FAO/WHO: Report of a Joint FAO/WHO Expert Consultation Bankok, Thailand (2002). expert consultation on human vitamin and mineral requirements.  pp. 223-229. Sobokola, O.P., Adeneran, O.M., Odedairo, A.A. and Kajihausa, O.E. (2010). Heavy Metal Levels of Some Fruits and Leafy Vegetables from Selected Markets in Lagos, Nigeria African Journal of Food Science 4(2): 383-393.  Sobolula, O.P., Dairo, O.U., Odunewu, A.V. and Fafiolu, B.O. (2007). Thin–layer drying process of some leafy vegetables under open sun. Food Science and Technology International 13(1): 35-40.  Sobukola, O.P. and Dairo, O.U. (2007). Modeling Drying Kinetics of fever leaves (Ocimum vinde) in a Convective hot air Dryer. Nigerian Food Journal 25(1): 145-153.  

Mineral Composition of Some Leafy Vegetables Consumed in Kano, Nigeria

Available online at http://www.ajol.info/index.php/njbas/index Nigerian Journal of Basic and Applied Science (2011), 19(2): 304-307   ISSN 0794-5698  Short Communication  Lead and Cadmium Levels of Five Commonly and Widely Consumed Leafy Vegetables in Kano State, Nigeria.   *M.I. Mohammed and N. Sharif  Department of Pure and Industrial Chemistry, Bayero University, P.M.B. 3011, Kano, Nigeria.  [*Corresponding author. E-mail address: musaimf@yahoo.com; Tel.: +23408033149483]  304 ABSTRACT: The levels of the hazardous metals (Pb and Cd) in five different leafy vegetable plant samples ( viz: Hibiscus cannabinus, Cassia tora, Vernonia  amygdalina, Corchorus olitorius, and Corchorus tridens) consumed by Kano inhabitants were investigated  and found to be at concentration below the environmental lead action level set by US EPA/WHO. Cadmium was not detected in the samples. Low concentration of Pb and absence of Cd in all the plant samples analyzed are clear indication that these may not exhibit toxicity effects due to any of these metals. The consumers are therefore safe from their toxicity effect. Keywords: Lead, Cadmium, Leafy Vegetables, Kano, Nigeria.  INTRODUCTION Leafy vegetable plants play a vital role in the diet of the inhabitants of Kano. Many workers reported that these leafy vegetables could be rich sources of minerals, although the bioavailability, pollution and other anti-nutritional factors considered to interfere with digestion and absorption of these minerals in the body have to be established.   Heavy metals have been reported to have both positive and negative roles in human life (Adriano, 1984; Dundar and Saglam, 2004). Some like cadmium, lead and mercury are major contaminants of food and may be considered an important problem to our environment while others like iron, zinc and copper are essential for biochemical reactions in the body (Zaidi et. al., 2005). Generally, most heavy metals are not biodegradable, have long biological half-lives and have the potential for accumulation in the different body organs leading to unwanted side effects (Jarup, 2003; Sathawara, et. al., 2004). There is a strong link between micronutrient nutrition of plants, animals and humans, the uptake and impact of contaminants in these organisms (De-Leonardis et. al., 2000; Yuzbasi et. al., 2003; Baslar et. al., 2005; Yaman et. al., 2005). The content of essential elements in plants is affected by the characteristics of the soil and the ability of plants to selectively accumulate some metals (Divrikli et. al., 2006)  Leafy vegetable are widely used for culinary purposes. They are used to improve the quality of soup and also for other dietary purposes (Sobukola et al., 2007). They are made up of chiefly cellulose, hemi-cellulose and pectin that give them their texture and firmness (Sobukola and Dairo, 2007). Fresh vegetables are of great importance in the diet because of the presence of vitamins and mineral salts. They are very important protective food and useful for the maintenance of health and the prevention and treatment of various disease (D’ Mellow, 2003). However, these plants contain both essential and toxic metals over a wide range of concentration (Radwan and Salama, 2006).    Based on persistent nature and cumulative behaviors as well as the probability of potential toxicity effect of heavy metals as a results of consumption of leafy vegetables and fruits, there is needs to test and analyze these foods items to ensure that the levels of these trace elements meet the agreed international requirements. This is particularly important for farm products produced from this part of the world where only limited data on heavy metals contents of such highly consumed agricultural material are available (Sobukota et al., 2010). Many workers have Nigerian Journal of Basic and Applied Science (2011), 19(2): 304-307 305 reported different levels of trace metals in vegetables. Anyoola et al. (2010) reported the trace elements and major minerals of Spondias mumbin, Vernonia amygdalina and Momordica charantia leaves. Asaolu and Asaolu (2010) reported the trace metal distribution in Nigerian leafy vegetables, which include Corchorus olitorius, Grassocephilium crepodes, Senecio biodrae,  Ammarantus caudus and Talium triangulase. Sobukola et al., (2010) studied the heavy metal levels of some fruits and leafy vegetables from selected markets in Lagos, Nigeria. e.t.c.    Materials and Method Sampling Five commonly and widely consumed leafy vegetables in Kano, Nigeria were selected for analysis. The varieties are viz; Hibiscus cannabinus, Cassia tora, Vernonia amygdalina, Corchorus olitorius, and Corchorus tridens. The vegetables were purchased from “Yan-Kaba market in Kano city, Nigeria.  Sample Preparation The leaves were separated in each case and they were cuts into pieces, washed, and air dried on the laboratory benches and then dried in the oven at 800C for six hours. The dried materials were grounded into powder using mortar and pestle. 2g of each powdered component were weighed and digested as reported by Anjorin et al. (2010). The digest were analyzed for the mineral contents using Buck scientific model 210VGP atomic absorption spectrophotometer.  Wet Digestion Method  Two grams of each of the powdered samples was weighed into separate beakers and treated with 20cm3 of concentrated HNO3 heated to reflux on an electric hot plate at 70-90oC for 60mins. The content of the beaker is allowed to cool, filtered through Whatman No. 42 filter paper into volumetric flasks and made up to 100cm3 with de-ionized water and kept for analysis. Blank was also prepared in similar manner (Anjorin et al, 2010).  Instrumentation  Metal concentrations were determined on a Buck scientific model 210VGP Atomic Absorption Spectrometer (AAS). The result of each sample was the average of three replicate readings. A calibration curve of absorbance against concentrations of each element under investigation was constructed and finally the concentration of each element was determined from the calibration curve of its standards by interpolation.  RESULTS AND DISCUSSION  Lead (Pb) In all the samples analyzed Pb levels was observed to vary from 0.048 mg/g in the leaves of Vernonia amygdalina to 0.119mg/g in the leaves of Cassia tora as shown in figure 1. Among the values reported previously for leafy vegetables. Dike (2010), reported Vernonia amygdalina  to have 0.0082 mg/g. Asaolu and Asaolu, (2010) also reported mean concentration of Pb in Corchorus olitorius to be 0.05mg/g. The values reported by Asaolu and Asaolu,(2010) are not significantly different from those reported in this work. Although the highest Pb level of 0.119mg/g as found in the leaves of Cassia tora, the value which has not exceed the environmental lead action level set by US EPA/WHO as reported by Mary (2009). Therefore the lead levels in the leafy parts of the vegetables analyzed seems not to be alarming except in a case of excessive consumption. Lead is non essential element in foods and natural waters. Automobile-exhaust ashes, batteries, bone meals, cigarette, petrol and lead accumulators/batteries are implicated as common sources of Pb in the environment (Nielson, 1996).  Knowing the toxicity effect and the essentialities of some of the trace metals in the environment on human health, it is of paramount importance for food hygienist and health authorities to be familiar with available information on some of the hazardous metal content of our food like the leafy vegetables (Asaolu and Asaolu, 2010). This information may serve as a guide to the nutritional value and pollution potential of some leafy vegetables due to their mineral contents.   Cadmium (Cd) Cadmium is also a non-essential element in foods and natural waters and it accumulates principally in the kidney and liver (Sobokola et. al., 2010). Cd was observed to be absent in all the samples Mohammed & Sharif: Lead and Cadmium Levels of five commonly and widely Consumed Leafy…. 306 analyzed. However some authors like Asaolu and Asaolu (2010) reported low cadmium concentration of 0.014mg/g in the leaves of Corchorus olitorius while Sobokola et. al. (2010) reported Vernonia amygdlina to have mean Cd concentration of 0.0006mg/g. Being Cd among the non-essential elements in foods,  its absence in these plants indicate that the plants contribute nothing to the toxic effects of this non-essential element.                                    CONCLUSION The goal of this study was to assess and compare the Pd and Cd contents of five leafy vegetables that are widely consumed by the inhabitants of Kano, Nigeria. Low concentration of Pd and absence of Cd in all the plant samples analyzed are clear indication that these plants contribute little or nothing to the toxic effect of these metals, and hence they can be consumed without fear of Pb and Cd toxicity.   REFERENCES Adriano, D.C. (1984). Trace metals in the Terrestial Environment. New York: Verlag Spiegler. 932 Anjorin, T.S., Ikokoh, P. and Okolona, S. (2010). Mineral Composition of Moringa oleifera leaves, Pods, and  seed from two region in Abuja, Nigeria. International Journal of Agriculture and Biology, 12: 431 – 434.  00.020.040.060.080.10.12Concentration mg/g VAR CTO CTR COL HCAFig 1; Mean concentration of Pb in leaves of samples analyzed  Key: VAR = Vernonia amygdalina,     CTO = Cassia tora,  COL = Corchorus olitorius,           CTR= Chorchorus tridens,        HCA= Hibiscus cannabinus     Nigerian Journal of Basic and Applied Science (2011), 19(2): 304-307 307  Anyoola, P.B., Adeyeye, A. and Onawumi, O.O. (2010). Trace Element and Major Evaluation of Spondias mombin, Vernonia anygdalina and Momordica charantia Leaves, Pakistan Journal of Nutrition, 9(8): 755-758. Asaolu, S.S. and Asaolu, M.F. (2010). Trace Metal Distribution in Nigerian Leafy Vegetables. Pakistan Journal of Nutrition, 9(1): 91-92. Baslar, S., Dogan, Y., Yenil, N., Karagoz, S. and Bag, H. (2005). Trace element biomonitoring by leaves of Populus nigra L. from Western Anatolia, Turkey Journal of Environment and Biology. 26: 665-668. De- Leonardis, A., Macciola, V. and De-Felice, M. (2000). Copper and iron determination in edible vegetable oils by graphite furnance atomic absorption spectophotometry after extraction with diluted nitric acid. International Journal of Food Science and Technology, 35: 371-375. D’Mello, J.P.F. (2003). Food Safety, Contaminat-ion and Toxins. CABI Publishing, Wallingford, Oxon, UK, Cambridge, MA, P. 480. Divrikli, U., Horzum, N., Soylak, M. and Elci, L. (2006). Trace heavy metal contents of some spices and herbal plants from western Antolia, Turkey International Journal of Food Science 41: 712-716.  Dike, M.C. (2010). Proximate, Phytochemical and Nutrient Compositions of Some Fruits, Seeds and Leaves of Some Plant Species at Umudike, Nigeria. ARPN Journal of Agricultural and Biological Science, 5(1): 7-16. Dundar, M.S. and Saglam, H.B. (2004). Determination of cadmium and vanadium in tea varieties and their infution in comparison with 2 infusion processes. Trace Element Electrolytes, 21: 60-63.  Jarup, L. (2003). Hazardous of heavy metals contamination. British Medical Bulleting, 68: 167-182. Mary, J. and Brown, R.N. (2009). Review of Lead Exposure Investigation, and Treatment, Centre for Disease Control and Prevention Kosovo. pp 42.  Nielson, F.H. (1996). Other Trace Elements in Present Knowledge of Nutrition. 7th edition, International life Science Institute Press, Washington D.C.; pp 353-377. Radwan, M.A. and Salama, A.K. (2006). Market Basket Survey for Some Heavy Metals in Egyptian Fruits and vegetables. Food Chemistry and Toxicology, 44: 1273-1278.   US EPA/ WHO: Report of a Joint FAO/WHO Expert Consultation Bankok, Thailand (2002). Expert consultation on human vitamin and mineral requirements.  pp. 223-229. Sathawara, N.G., Parikish, D.J. and Agrwal, Y.K. (2004). Essentials heavy metals in environmental samples from western India. Bulleting of Environmental Contamination and Toxicology 73: 756-761. Sobokola, O.P., Adeneran, O.M., Odedairo, A.A. and Kajihausa, O.E. (2010). Heavy Metal Levels of Some Fruits and Leafy Vegetables from Selected Markets in Lagos, Nigeria. African Journal of Food Science, 4(2): 383-393.  Sobolula, O.P., Dairo, O.U., Odunewu, A.V. and Fafiolu, B.O. (2007). Thin–layer drying process of some leafy vegetables under open sun. Food Science and Technology International, 13(1): 35-40. Sobukola, O.P. and Dairo, O.U. (2007). Modeling Drying Kinetics of fever leaves (Ocimum vinde) in a Convective hot air Dryer. Nigerian African Journal of Food Sciences, 25(1): 145-153. Yaman, M., Okumus, N., Bakirdere, S. and Akdenez, I. (2005). Zinc speciation in soils and relation with its concentration in fruits. Asian Journal of Chemistry, 17: 66-72. Yuzbasi, N., Sezgin, E. and  Yildirim, Z. (2003). Survey of lead, cadmium, iron, copper and zinc in Kasar cheese. Food Additives and Contamination. 20: 464-469. Zaidi, M. I., Asrar, A., Mansur, A. and Farooqui, M.A.(2005). Heavy metal concentrations along  road sides trees of quetta and its effects on public health. Journal of  Applied Science, 5(4): 708-711.  

Lead and Cadmium Levels of Five Commonly and Widely Consumed Leafy Vegetables in Kano State, Nigeria

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Lead and Cadmium Levels of Five Commonly and Widely Consumed Leafy Vegetables in Kano State, Nigeria

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