1.0 Introduction
1.1 Background of study
Heavy metals pose serious health challenges especially among occupationally exposed workers. Work has it’s positive health promoting effects, as the financial benefits provides the worker with the basic necessities of life. There is however a reciprocal and interactive relationship between the workers and the work environment.
Occupational hazard is the risk, harm or danger that an individual is exposed to at the workplace, whereas occupational diseases result from such exposures to the individual (WHO, 1986). Although these occupational diseases appear less frequently, there is evidence that they affect a considerable number of people particularly in rapidly industrializing countries.
Thousands of toxic chemicals pose serious health hazard, potentially causing cancer, respiratory and skin disease as well as adverse effects on the reproductive function and around 350 chemical substances have been identified as occupational carcinogens (WHO, 2000).
Heavy metals are natural components of the earth’s crust. These elements are the oldest toxins known to humans, having been used for thousands of years. They are group of environmental chemicals which are ubiquitous and non-biodegradable. Many different definitions of heavy metals have been proposed. One of such definitions entails that heavy metals are defined as metallic elements that have a relatively high density compared to water (Fergusson, 1990). Due to increase in automobiles and urbanization in towns and cities in the world, there is an exponential increase in exposure to toxicants which include heavy metals, solvents and vehicles exhaust, gasoline, paints, dust and silica exposure from sundry, sand blasting etc. Heavy metals are significant environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionally, nutritional and environmental reasons (Jaishankar, Mathew, Shah, & Gowda, 2014; Nagajyoti , Lee, & Sreekanth, 2010).
These metals are essential to maintain various biochemical and physiological functions in living organism, when in very low concentrations; however they become noxious when they exceed certain threshold concentrations. Although these metals have crucial biological functions in plants and animals, sometimes their chemical coordination and oxidation-reduction properties have given them an additional benefit so that they can escape control mechanisms such as homeostasis, transport, compartmentalization and binding to required cell constituents. They displace original metals from their binding sites causing malfunctioning of cells and ultimately toxicity. Previous research has found that oxidative deterioration of biological macromolecules is primarily due to binding of heavy metals to the DNA and nuclear proteins (Flora, Mittal & Mehta, 2008).
Among workers occupationally exposed to heavy metals include: automobile technicians otherwise known as mechanics. They are made up of spray painters, welders, panel beaters and brake and clutch liners etc. Those in the automobile repairs industry constitute a significant number of those practicing vocational trade in Nigeria (Anyadike, Emeh, & Ukah, 2012). One of the many hazardous habits automobile technicians engage in include sucking of fuel (Oluwagbemi,
2007; Anetor, Babalola, Adeniyi, & Akingbola, 2002; Landrigan, 1989); washing of hands and vehicle parts with gasoline (Oluwagbeni, 2007; Udonwa, Uko, Ikpeme, Ibanga & Okon, 2009) and applying diesel to bruised body parts (Omokhodion, 1999).
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