<P> BLL measurements from developed countries decreased markedly beginning in the late 1970s, when restrictions were placed upon lead use in gasoline, petrol, paint, soldering material and other products . In the United States, average BLLs measured among tens of thousands of subjects declined from 12.8 to 2.8 μg / dL between 1976 and 1991 . In the 1990s, BLLs of children in Australia were measured to be 5 μg / dL, and 9 μg / dL in Barcelona, Spain . </P> <P> In the United States, blood lead levels remain highest for children, for people in urban centers, for people of lower socioeconomic status, and for minorities . </P> <P> Exposure to lead occurs through ingestion, inhalation, and dermal contact . Lead enters the bloodstream through exposure and elevates blood lead level that may result in lead poisoning or an elevated blood lead level . For example, a child can ingest lead by chewing on a toy that is made of lead - contaminated metal or is painted with lead - contaminated paint . </P> <P> A major source of exposure to lead comes from inhalation . Factories and industries, vehicle exhaust (especially from vehicles using leaded gasoline), and even dust in the air that people breathe all have the potential of containing lead . Other major sources of lead exposure include ingestion and contact with products such as paint and soil that may contain lead . Many older claw - foot bathtubs have also been found to leach lead, especially when filled with warm bath water . </P>

Lead poisoning can result in death if a level of micrograms per deciliter of blood is reached