الفهرس 
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Abstract
The natural environment is necessary for the existence of present and future generations. Our industrialized society has left a toxic footprint in our environment (Singh et al., 2010). Heavy metals occur naturally in the ecosystem with large variations in concentration. Toxic levels for some heavy metals can be just above the background concentrations naturally found in nature (Ferner, 2001). Advertently or inadvertently we are becoming more and more exposed to them (Singh et al., 2010). The way by which a toxic substance is introduced into a complex system of an organism is strongly dependent upon the physical and chemical properties of the substance (Sharma & Kantwa, 2011). These metals are particularly dangerous because once they are absorbed into the bodies, they tend to spread through the entire system, bio accumulate in the body tissues and organs and manifest their presence in the form of some diseases or disability (Babalola et al., 2005 and Singh et al., 2010). Intake of these harmful toxicants is via variable routes oral, dermal and inhalation (Singh et al., 2010).
Lead (Pb) ranks as one of the most serious environmental pollutant amongst the toxic heavy metals all over the world, because of its broad spectrum of use (Babalola et al., 2009). It induces a broad range of physiological, biochemical and behavioral dysfunctions (Needleman & Bellinger, 1991) through exposure from air, water, soil and food source (Herman et al., 2007) and it has no known beneficial or desirable nutritional effect (Patrick, 2006).
In view of the long history of Pb toxicity and the extensive publications one would think that Pb exposure is controlled up to a major extent and Pb poisoning is merely a historical entity. Unfortunately, this is not the case; there is still clinical Pb poisoning that occasionally occurs (Levin et al., 1997). It is important to inform about Pb as it is a versatile heavy metal and to take protective measures against its excessive exposure that if unrecognized or inappropriately treated, its toxicity can result in reduced quality of life (Ferner, 2001).
Characteristics and uses of lead
Lead is of major global concern because of its persistence in the environment (Vaglenov et al., 2001) and its significant role in modern industry, it has been known since ancient times and it is still being used recklessly (Valverde et al., 2002).
It has been used comprehensively for both industrial and domestic applications for hundreds of years (Sharma & Kantwa, 2011). Occupational Pb exposure may occur during Pb smelting processes, the manufacture of batteries, painting, printing, pottery and ceramic glazing, in plastic recycling industries, construction of tank linings, piping and other equipments that carries corrosive gases and liquids, superconductors, and fiber optic technologies (Harbison, 1998 and Patel et al., 2001), also during magnetic resonance imaging, and nuclear medicine (A.T.S.D.R., 2007). Other important sources of Pb exposure may include gasoline additives, food can solder, drinking water system and cosmetics (Babalola et al., 2009). Several Pb alloys are also widely used. Lead occurs in a variety of organic and inorganic compounds with a multitude of additional uses. The manipulation of Pb for these uses has caused Pb contamination of air, water, and soil.
Introduction
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Vegetables are polluted by Pb from the air and a considerable amount of Pb contamination is found in cereals and broad leafed vegetables (Sujatha et al., 2011). All sources of Pb contribute to an increased in permissible exposure limit (Harbison, 1998). Both occupational and environmental exposures to Pb remain a serious problem in many developing and industrializing countries (Yücebilgic et al., 2003).
Lead is excreted from the body mainly in the urine, but also in the feces, and small amounts also appear in hair, nails, sweat, saliva, and breast milk (Sharma & Kantwa, 2011). Both children and adults are affected by Pb not only morphologically but also anatomically and histologically. Various organs also show critical damage (Pizzol et al.