CHAPTER ONE
INTRODUCTION
1.1 Background to the Study
Of all natural resources available to man and vital to man‘s existence and survival, none is as abundant as water. Contaminated water jeopardizes both the physical and social health of all people. It is an affront to human dignity‖ (WHO, 2002). Water is vital to the existence of all living organisms, but this valued resource is increasingly being threatened as human populations grow and demand more water of high quality for domestic purposes and economic activities. Globally, the rate of groundwater abstraction is increasing by 1% to 2% per year (WWAP, 2012).Water abstraction for domestic use, agricultural production, mining, industrial production, power generation, and forestry practices can lead to deterioration in water quality and quantity that impact not only the aquatic ecosystem, but also the availability of safe water for human consumption (UNEP, 2006). In spite of the essential role played by water in supporting human life, it also has great potential for transmitting a wide variety of diseases and illnesses (Hutton, 1983).Indeed, understanding the impacts of contaminants on the environment, including the organisms which live in it, is rather complicated (Iscan, 2004). The world’s rivers are so badly affected by human activity that the water security of almost 5 billion people and the survival of thousands of aquatic species are reportedlythreatened (Vaugham, 2010). Even the world’s great rivers, such as the Yangtze, the Nile and the Ganges, are reportedly suffering serious biodiversity and water security stress (Vaugham, 2010). It has been suggested that water pollution is the leading cause of deaths and diseases, worldwide (Pink,2006).Disposing of sewage waste is a major problem with billions of people on the planet. According to 2013 figures from the World Health Organization (WHO), some 780 million people (11 percent of the world’s population) have no access to safe drinking water, while 2.5 billion (40 percent of the world’s population) have no proper sanitation (hygienic toilet facilities); although there have been great improvements in securing access to clean water, relatively little progress has been made on improving global sanitation in the last decade. Sewage disposal affects people’s immediate environments and leads to water-related illnesses such as diarrhea that kills 760,000 children under five each year (WHO, 2013).It has been reported that more than one-third of the global population(some 2.4 billion people) do not use improved sanitation facilities; of these, one billion people still practice open defecation (UNICEF/WHO, 2015). Rapid increasein industrial development has created more awareness in interrelationship between pollution, environment and public health. Industrial development results in the generation of industrial effluents, and if untreated results in water, sediment and soil pollution. (Fakayode and Onianwa, 2002; Fakayode, 2005). Industrial wastes and emission contain toxic and hazardous substances, most of which are detrimental to human health (Ogunfowokan et al.,2005; Jimena et al.,2008; Rajaram et al.,2008). Heavy metals from industrial processes are of special concern because they pollute water and cause chronic poisoning to aquatic animals (Ellis, 1989).While some heavy metals are purely toxic with no cellular role (Shi et al.,2002),other metals are essential for life at low concentrations but become toxic at high concentrations (Badar et al. 2000).It is recognized that a considerable quantity of industrial, domestic and transportation wastes and by-products end up in waterways. The results had devastating consequencies on environmental and biological systems hence it is important to constantly assess the risk factors on the ecosystem (Iscan, 2004). Sokoto is a cosmopolitan town supposed to have regular potable water supply. Unfortunately, potable water supply is not only irregular but does not reach a large percentage of the populace. This irregularity in potable water supply must have prompted the populace to seek for alternative sources of drinking water by resorting to well, sachet and even river water in order to meet their domestic water needs.