**1. Introduction**

The issues of heavy metals contamination of local, regional, and global environment emanate directly from natural sources and indirectly from anthropogenic activities such as mining, rapid industrialization, urbanization, improper waste management, and other local and regional man-made activities [1].

Substantial quantities of heavy metals are released from different anthropogenic sources into the atmosphere from where they are deposited in soils and aquatic ecosystem through dry and wet deposition processes.

Anthropogenic inputs of heavy metals are currently getting higher and in some areas exceeding natural inputs where human activities are predominant [2, 3]. The metals accumulation and distribution in soil, water, and environment are increasing at a faster rate causing deposition and sedimentation in water reservoirs and affecting

aquatic organisms [4, 5]. High levels of Cd, Cu, Pb, and Fe can act as ecological toxins in aquatic and terrestrial ecosystems [6].

Heavy metals are potentially harmful to humans and various ecological receptors due to their toxicity, persistence, bio-accumulative characteristics, and their nonbiodegradable nature. Toxic metals can cause different health problems depending on the type of the metal concerned, its concentration, and oxidation state. They are among the most toxic and persistent pollutants in freshwater systems [4, 5]. Certain heavy metals and metalloids are toxic and can cause adverse effects and severe problems such as oxidative stress by formation of free radicals even at low concentrations [7, 8].

Heavy metals contamination can result in several diseases and deformities; for instance, in the 1950s, an advanced country such as Japan was devastated by heavy metal poisoning known as the Fetal Minamata Disease, which resulted from contamination of fishes by organic mercury. The situation led to severe nerve damage of newborn babies from pregnant women [9].

In Iraq, babies walked at later age due to consumption of organic mercury contaminated grains by pregnant mothers. Similar incidence occurred in Faroe Islands where school children scored lower grades on brain function test due to consumption of mercury-contaminated whale meat by pregnant women [10].

A third world country such as Bangladesh in recent years has become vulnerable to heavy metal contamination of groundwater [11] and heavy metals contamination of drinking water sources by Cd, Pb, Cu, and Zn in Bolivia, Hong Kong, and Berlin [12, 13].

Efforts were made in both research and monitoring to establish sources, transport, and fate of these metals in the aquatic environment. However, studies have shown that contamination artifacts have seriously compromised the reliability of many past and current analyses and under certain circumstances, metal concentrations have been measured 100 times the true concentrations [14]. These errors are of great concern, since contaminant-free data are necessary to detect trends and to identify factors that control the transport and fate of toxic metals in water bodies.

Many mineral resources including gold represent significant material basis for socioeconomic development, justifying the exploitation and utilization of mineral resources essential to national development. Nonetheless, despite the importance of mineral resources, mineral extraction with its associated release of heavy metals has caused serious environmental damage in many developing and developed countries [15, 16].

As gold mineral is being mined actively in many developing countries, there are fears that the mining activity may be causing serious metal pollution to water resources. Disused and closed mines with huge mine waste materials including tailings were left from the extraction processes without adequate treatment, and as a result, soils, plants, water bodies, and sediments in the vicinity of mines were contaminated by potentially toxic metals from tailings through wind and Acid-Mine-Drainage [17, 18]. Reports from earlier studies have shown that metal levels of surface and groundwater exceeded World Health Organization (WHO)'s acceptable limits for drinking water around Tarkwa mining area [19]. Huge deposits of mine wastes as well as ore stockpiles and waste rocks are usually seen in large piles around both large- and small-scale mining areas. These deposits are gradually washed through weathering and leaching into far and near water bodies, thereby releasing toxic substances into water bodies [20].

### *Effect of Mining on Heavy Metals Toxicity and Health Risk in Selected Rivers of Ghana DOI: http://dx.doi.org/10.5772/intechopen.102093*

Metals associated with gold mines, including Cd, Cu, Pb, and Zn, may be dispersed downstream due to the weathering process of tailings. Thus, the extent and degree of heavy metal contamination around mines may vary depending on geochemical characteristics and mineralization of tailings [21].

Mine tailings may result in the influx of metals and toxic chemicals into the environment. Waste rocks are known to contain arsenic (As), mercury (Hg), cadmium (Cd), lead (Pb), and other toxic metals, which are extensively dispersed into the environment [22]. According to the recent World Health Organization (WHO) report on arsenic, it was recognized that at least 140 million people in 50 countries have been drinking water containing arsenic at levels above the WHO provisional guideline value of 10 μg/L [22, 23]. In the evaluation conclusions, arsenic and other heavy metals exposure through drinking water is causally related to cancer in the lungs, kidney, bladder, and skin. There is also an increased risk of skin cancer and other skin lesions, such as hyperkeratosis and pigmentation changes. Ingestion of inorganic arsenic may induce peripheral vascular disease, which leads to black foot disease [24, 25].

It is therefore imperative to continually assess and monitor the concentration of heavy metals in water bodies in the environment due to anthropogenic activities, including gold mining, for evaluation of human exposure and for sustainable environment [26, 27].

This study investigated the extent of contamination by heavy metals of selected water bodies in the vicinity of gold mines and further compared the metal levels with those from the pristine sites to assess the possibility of mining activities causing toxicity (contamination) of the water bodies.
