Sources and routes of exposure

Lead exposure can come from many sources.

People can become exposed to lead through occupational and environmental sources.

This mainly results from:

  • inhalation of lead particles generated by burning materials containing lead, for example, during stripping leaded paint, smelting, recycling, and using leaded petrol or leaded aviation fuel; and
  • ingestion of lead-contaminated dust from sanding or disturbance of old lead containing paint, water (from leaded pipes), and food (from lead-glazed or lead-soldered containers).

Young children are particularly vulnerable to lead poisoning because they absorb 4–5 times as much ingested lead as adults from a given source. Moreover, children’s innate curiosity and their age-appropriate hand-to-mouth behaviour result in their mouthing and swallowing lead-containing or lead-coated objects, such as contaminated soil or dust and flakes from decaying lead-containing paint. This route of exposure is magnified in children with a psychological disorder called pica (persistent and compulsive cravings to eat non-food items), who may, for example pick away at, and eat, leaded paint from walls, door frames and furniture. Exposure to lead-contaminated soil and dust resulting from battery recycling and mining has caused mass lead poisoning and multiple deaths in young children in Nigeria, Senegal and other countries.

Once lead enters the body, it is distributed to organs such as the brain, kidneys, liver and bones. The body stores lead in the teeth and bones where it accumulates over time. Lead stored in bone may be remobilised into the blood during pregnancy, thus exposing the foetus. Undernourished children are more susceptible to lead because their bodies absorb more lead if other nutrients, such as calcium or iron, are lacking. Children at highest risk are the very young (including the developing foetus) and the impoverished.