1.1 Introduction
Heavy metals are natural elements with atomic number greater than 20, characterized by a relatively high density (at least 5 g cm−3), and are toxic even at low concentrations (Koller et al. 2018). They are characteristically existing components found in changing variation in the environments and are part of human daily activities, they are also found in important structures and in a range of other artificial mixes (Govind et al., 2014). The activities of human have greatly impacted on some heavy metal biochemical cycles and equalization of which a great number of heavy metals have found its use in various items such as cars and batteries (Oyeleke et al., 2016).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Research hypothesis and questions, Limitation of the study and Definition of technical terms.
1.2 Background of 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 background concentrations. The distribution of metals in the environment is governed by the properties of the metal and influences of environmental factors (Khlifi & Hamza-Chaffai, 2010). Of the 92 naturally occurring elements, approximately 30 metals and metalloids are potentially toxic to humans, Be, B, Li, Al, Ti, V, Cr, Mn, Co, Ni, Cu, As, Se, Sr, Mo, Pd, Ag, Cd, Sn, Sb, Te, Cs, Ba, W, Pt, Au, Hg, Pb, and Bi. Heavy metals is the generic term for metallic elements having an atomic weight higher than 40.04 (the atomic mass of Ca) (Ming-Ho, 2005). Heavy metals enter the environment by natural and anthropogenic means. Such sources include: natural weathering of the earth’s crust, mining, soil erosion, industrial discharge, urban runoff, sewage effluents, pest or disease control agents applied to plants, air pollution fallout, and a number of others (Ming-Ho, 2005).
Although some individuals are primarily exposed to these contaminants in the workplace, for most people the main route of exposure to these toxic elements is through the diet (food and water). The contamination chain of heavy metals almost always follows a cyclic order: industry, atmosphere, soil, water, foods and human. Although toxicity and the resulting threat to human health of any contaminant are, of course, a function of concentration, it is well-known that chronic exposure to heavy metals and metalloids at relatively low levels can cause adverse effects (Agency for Toxic Substance and Disease Registry [ATSDR], 2003a, 2003b, 2007, 2008; Castro-González & Méndez-Armenta, 2008). Therefore, there has been increasing concern, mainly in the developed world, about exposures, intakes and absorption of heavy metals by humans. Populations are increasingly demanding a cleaner environment in general, and reductions in the amounts of contaminants reaching people as a result of increasing human activities. A practical implication of this trend, in the developed countries, has been the imposition of new and more restrictive regulations (European Commission, 2006; Figueroa, 2008).
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Effects of Heavy Metal on Human Respiratory System.
1.3 Statement of Problems
The concentration of heavy metals may very well be too low to be of significant concern, but it’s definitely a legitimate reason to avoid eating sizable portions of chocolate on a regular basis. Furthermore, because the cacao beans used to make chocolate come from all over the world, the amounts of heavy metals that they contain can vary widely. Although there’s no guarantee, certified organic chocolate is less likely to be produced from cacao beans that have been grown in a contaminated environment or exposed to contaminants during processing (Carter-Pokras et al., 2007).
The major heavy metals of concern include lead, cadmium, arsenic, mercury, copper and chromium because of their toxic impact on human health; for instance, environmental exposure to high concentrations of heavy metals has been linked with various cancers and kidney issues (García et al., 2016). Heavy metals have also greatly affected soil microorganisms and plants growth and development (Sharma et al., 2018). The presence of heavy metals in the environment has been a source of concern over the past few decades due to their persistence, potential harm and toxicological hazards (Ali et al., 2019). Besides the fact that they are non-biodegradable, they may also undergo microbial or chemical transformation (Nwidi et al., 2015). Recently, Hasani et al. (2019) and Nath et al. (2019) reported that heavy metal polluted environments activate co-selection process and cause a decrease in microbial tolerance to antibiotics due to their ability to co-regulate genes responsible for antibiotic resistance.
1.4 Aim and Objectives of Study
The aim of the study is to investigate the Effects of Heavy Metal on Human Respiratory System. In achieving this aim, the following specific objectives were laid out as follows:
- To assess the human respiratory system exposure to heavy metals
- To find out the Heavy Metal causing harm on Human Respiratory System
- To explore the methods involved in Heavy metals determination in human respiratory system
1.5 Significance of Study
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.6 Scope of Study
The study focuses on the Effects of Heavy Metal on Human Respiratory System using Enugu State Primary Health Care (PHC) as a case study.
1.7 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
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