Lead poisoning or lead poisoning is the product of excessive human exposure to this metal, which can occur by inhaling fumes and particles that contain it (for example, from smelting) or by ingesting dust (for example, paint chips with lead), contaminated water (piped through lead pipes), or food (stored in lead-lined or welded containers). This exposure can last for a short time (acute poisoning) or for a long time (chronic poisoning). To date, it has not been shown that there is a specific level of exposure to lead that is not harmful.

For this reason, some health authorities define excessive exposure as the presence in blood of a concentration higher than the general reference value in the population, which is usually the concentration of lead in blood in 2.5% or 5% of the population with higher exposure, that is, at the 97.5th or 95th percentile, respectively. For example, in the United States of America, a reference value of 5 μg/dl was established in 2012, based on the 97.5th percentile of blood lead concentrations found in children under 6 years of age between 2008 and 2012 (2) . In France, the concentration of 5 μg/dl is the 98th percentile value for children under 7 years of age (3).