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ABSTRACT:
Ogoniland and it’s environs have been heavily impacted by environmental pollution and soil contamination. This study was carried out to determine the concentrations of Cd, Co,Cr, Cu, Fe, Mn, Ni, Pb, and Zn in fluted pumpkin. The vegetables were digested with a mixture of perchloric acid and nitric acid in the ratio of 1:4 and analysed with Atomic Absorption Spectrophotometer (AAS). The result obtained showed that the concentrations of these metals were above FAO/WHO acceptable limit. These high concentration of heavy metals detected at the sites may be due to atmospheric pollution, and the consumption of these vegetables will expose the consumers to heavy metal toxicity as the years go by which will lead to a lot of health complications.
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY;
Metals occur naturally in the earth’s crust, and their contents in the environment can vary between different regions resulting in spatial variations of back ground concentrations. The distribution of metals in the environment is governed by the properties of the metal and influences of environmental factors. (Khlifi and Hamza – Chaffai, 2010)
Metals are notable for their wide environmental dispersion from such activity their tendency to accumulate in selected tissues of the human body.Metal toxicity or metal poisoning is the toxic effect of certain metals in certain forms and doses on life. Some metals are toxic when they form poisonous soluble compounds.
Certain metals have no biological role, that is they are not essential minerals, or are toxic when in a certain form.
Cd is an extremely toxic metal commonly found in industrial workplaces due to its low permissible exposure limit, overexposure may occur even in situation where trace quantities of Cd are found. Inhalation of Cd fumes or particles can be life threatening and although acute pulmonary effect and deaths are uncommon, sporadic cases still occur. (Barbeejyand Prince Ts, 1999).
Cr is present in rocks, soil, animals and plants. It can be solid, liquid and in the form of gas. Exposure to higher amounts of chromium compounds in humans can lead to the inhibition of erythrocyte glutathione reductase, which in turn lowers the capacity to reduce methemoglobin to hemoglobin (Koutras etal., 1965, Schlafter & Kissling 1975).
Co toxicity,also called copperiedus, refers to the consequences of an excess of copper in the body. Copperiedus can occur from eating acid foods cooked in uncoated copper cook ware, or from exposure to excess copper in drinking water, as a side effect of estrogen birth control pill, or other environmental sources. It can also result from the genetic condition Wilsons disease.
Fe is the second most abundant metal on the earth’s crust (EPA, 1993). Fe is a most crucial element for growth and survival of almost all living organisms (Valko et al., 2005).
The Fe produced hydrogen free radicals attack DNA, resulting in cellular damage, mutation and malignant transformations which in turn cause an array of diseases (Grazulevicience et al., 2009).
Mn poisoning is a toxic condition resulting from chronic exposure to Mn and first identified in 1837 by James Couper (Tenenbein, Milton 2005).
Ni is said to be deadly if it surpasses the allowed amount in edibles (Nriagu and Pacyna, 1988).
The general population is exposed to Pb from air and food is roughly equal proportions Earlier, Pb in foodstuff originated from pots used for cooking and storage, and Pb acetate was previously used to sweeten port wine. Pb interferes with a variety of body processes and is toxic to many organs and tissues including the heart, bones, intestines, kidneys, and reproductive and nervous system. The supply of various bio solids for example; composts, cattle’s manure and municipal sewage sludge (MSS) to land unconsciously, points towards the build up of heavy metals like Cd ,Co, Cr, Cu, Fe, Mn, Ni, Pb & Zn in the soil (Basta et al., 2005).
Heavy metals are generally referred to as those metals which possess specific density of more than 5g/cm¬¬3 and affect the environment and living organisms. (Jarupl, 2003).
Heavy metals enter the surrounding by natural means and through human activities, various sources of heavy metals include soil erosion , natural weathering of the earths crust, mining, industrial effluents, urban runoff, sewage discharge, insect or disease control agents applied to crop and many others.(Morais etal., 2012).
Heavy metals are toxic because they tend to bio accumulate in plants and animals,bio-concentrate in the food chain and attack specific organs in the body(chatterjee and chatterjee 2000:Akinola etal.,2008).
Heavy metals are significant for ecological, evolutionary, nutritional and environmental reasons(Jaishanker etal., 2013; Nagajyoti eta.,2010).People may be exposed to potentially harmful chemical, physical and biological agent in air, food, water or soil, however, exposure does not result only from the presence of a harmful agent in the environment. The key word in the definition of exposure is contact(Berlung etal., 2001).There must be contact between the agent and the outer boundary of the human body. Exposure is often defined as a function of concentration and time. Therefore, there has been increasing concern, mainly in the developed world, about exposure, intakes and absorptions of heavy metals by humans. Populations are increasing demanding a cleaner environment in general,reductions in the amount of contaminants reaching people as a result of increasing human activities. A practical implication of the trend, in the developed countries has been the imposition of new and more restrictive regulations (European commission (2006); Figueroa (2008).
1.2 STATEMENT OF PROBLEM
In view of avoiding undesirable health hazard consequent of “excessive” intake of toxicants (including toxic metals) international and national scientific organisms such as FAO/WHO, FOA, European union etc have used the safety factor approach for establishing acceptable or tolerable intakes of substances that exhibit threshold toxicity.
Most farmers are ignorant of the consequences of growing crops in contaminated soils. Plants grown in polluted environment can accumulate heavy metals in high concentration causing serious risk to human health when consumed.
Fluted pumpkin (Telfairia occidentalis,) probably originated from the south eastern Nigeria, and is widely distributed.(Esiaba, 1982; Burkill, 1985; Akoroda, 1990).
Fluted pumpkin is a creeping vegetable that spread low across theground with lobed leaves and long twisting tendrils. It is warm weather crops which grows well in low lands and tolerate elevation of some few meters above the ground. It thrives best in soils rich in organic matter. Fluted pumpkin as it is commonly known in southern Nigeria, plays important role in human and livestock nutrition. It is a source of protein, oil, fats, minerals and vitamins (Oyenuga, 1968; Ifon, 1977; Okoli etal., 1988; Aletor and Adeogun, 1995).
The leaves and seeds are used as vegetables. The tender leaves, succulent leaves and immature seed are cooked and consumed as vegetable. Fluted pumpkin is high antioxidant and free radical scavenger properties and that may contribute to why many use the leave extract in oxidative damage condition such as cancers, liver and liver disease. In Nigeria the fresh leaves are grounded and the juice used as tonic by women that have just given birth, its high iron content assist in the replenishment of lost blood, being used for treatment of anemia, chronic fatigue and diabetes (Alada, 2010; Dina et al., 2006; Aderibigibe et al., 1999).
Using chemical products as nutrients, fertilizers and pesticides, we believe that we attack our safety and we must know the effects of heavy metal from these compounds. That implies a new rapid method to determine the transfer of this chemical compounds from soil to the plants (Krauss et al., 2002).
1.3 AIMS AND OBJECTIVES
This study is aimed at determining the concentration of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in fluted pumpkin (TelfiariaOccidentalis) harvested in Bori metropolis and comparing the results obtained with FAO/WHO acceptable limit. Also to ascertain the level of heavy metals in theanalyzed samples, the health implications when these vegetables are consumed and recommend appropriate measures on the impact.
1.4 SCOPE OF THE STUDY
The study area include Zaapkon and Ken Saro- wiwa polytechnic botanical garden having a distance of 674.81m between them, all in khana local government area of Rivers state Nigeria, as shown in the map.
1.5 SIGNIFICANT OF THE STUDY
The significant of the study are stated as follows;
- To determine the concentration of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn, in fluted pumpkin (TelfiariaOccidentalis) harvested in Bori metropolis.
- To know if fluted pumpkin (TelfiariaOccidentalis) planted on such farms are safe for human consumption .
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