**4.2 Clinical implication of delayed lead bullet elimination**

The lead clearance of 1.2 l/kg/h agrees with the reported value of 1.18 l/kg/h [58]. Our findings agree with the report indicating that, other methods can complement the application of LD50 for discovery of potential toxicants. Such methods could aim at encouraging replacement, refinement and reduction [23]. Many scaling factors are determined experimentally, as all scaling factors have uncertainty associated with them. Mathematics of translation from one species to another requires multiple experimentally estimated scaling factors [59]. The developmental effects of lead occur at the age (>2 years). Low level of lead (>10 μg/dl) is associated with adverse effect in the developing child [60] and inversely proportional to neuropsychological development in the first 7 years of life [61]. The reported average blood lead concentration in child aged 1 and 5 years are 0.03 mg/l (3 μg/dl) and 0.11 mg/l (11 μg/dl), respectively. The elimination half-life in adult is 1 and 10 months in children [62]. Circulation of lead after absorption is 30 days. It diffuses into soft tissues including brain, and after 2 min diffuses into bone with blood half-life of 30 days and bone half-life of 20– 30 years [63]. Also, half-life of lead in blood is 1–1.5 months and 25–30 years in bone respectively. However, Center for Disease Control (CDC) has defined poisoning level of lead equals or greater than 5 μg/dl [64]. Blood lead concentration of 9.1 μg/dl causes bad mood, headache, memory loss, daylight drowsiness, trembling, tingling of limb among others. Hence there is no known level of lead exposure considered safe [65]. This confirms that lead can enter brain because, it has a molecular weight of 207.2 g [66]. The total elimination half-life of lead is greater than 18 months. The primary route of elimination is urine [67], suggesting that urine is the most important sample in forensic toxicology of lead poisoning. Therefore, governments at various levels and law enforcement agents should curtail the use of lead bullet, so as to avoid damage to physical and intellectual capacity of affected humans [68]. Blood lead concentration (391 μg/dl) requires the use of calcium EDTA, but lead (49 μg/dl) can be neutralized using 600 mg succimer, three times daily for 14 days [69].
