Lead has atomic number 82 (symbol Pb) and is one of the heavy metals. Lead is a persistent metal and because of its unusual physical–chemical properties it is used in various industrial applications (Brannvall et al., 1999). Well known is its use as a radiation shield. Lead is a toxic metal to humans and animals and its persistency causes prolonged occurrence in the environment – in water, soil, dust and in manufactured products containing lead.
Since young organisms bear the heaviest burden of sensitivity to lead exposure, lead-based paint covers represent a serious health threat to children worldwide (Kumar and Clark, 2009). Soil containing lead also represent a serious hazard for children.
Similar to other persistent toxic metals such as arsenic, cadmium and mercury, lead damages cellular components via elevated (80 K. Jomova, M. Valko / Toxicology 283 (2011) 65–87) levels of oxidative stress. The pathogenetic effect of lead is multifactorial since it directly interrupts the activity of enzymes, competitively inhibits absorption of important trace minerals and deactivates antioxidant sulphydryl pools (Patrick, 2006b). Gastrointestinal absorption of lead is higher in children (40–50%) than in adults (3–10%). Lead toxicity is most commonly diagnosed through elevated blood levels. Blood levels of 10 g/dL (equivalent to 0.48 mol/L) or higher are considered toxic and result in neurological disorders, cognitive impairments, hypertension and other disorders (Patrick, 2006a).