Filter paper lead testing.

Lead is a common toxic metal in our environment. It is present at high concentrations (up to 600 g/kg) in some paints manufactured before 1970. Some artistic ceramic products and leaded glass contain substantial amounts of lead that can be leached by weak acids such as vinegar and fruit juices. Lead is also found in dirt from areas adjacent to buildings painted with lead-based paints and on highways, where it has accumulated from previous use of leaded gasoline in automobiles. Water transported through lead or lead-soldered pipe contains some lead, with higher concentrations found in water that is acidic. Some traditional home medicines contain lead. As a result of all of these opportunities for exposure, a person may be exposed to lead ranging from 5 to 200 ␮g per day in the United States, of which 1–10% is absorbed. Children may absorb as much as 50% of the dietary intake, and the fraction of lead absorbed is enhanced by nutritional deficiency. Exposure to lead from any of these sources by ingestion, inhalation, or dermal contact can contribute to significant toxicity. The finding that lead body burden contributes significantly to decreased intellectual capability in children is of considerable interest and concern (1). Young children have greater opportunity for exposure because they tend to spend time on the floor of the building they are in; in older homes previously treated with lead-based paints, lead-laden paint chips and dust accumulate on the floor where children are likely to pick them up and put them in their mouths. Guidelines published in the United States by the Center for Disease Control and Prevention (CDC) indicate that measurement of lead in whole blood is the preferred test for detecting lead effects in children (2). Chronic whole blood lead concentrations Ͻ0.49 ␮mol/L (10 ␮g/dL) are considered acceptable in children. The CDC recommends that chelation therapy be considered when the whole blood lead concentration exceeds 1 ␮mol/L (20 ␮g/dL) in children, and chelation therapy is indicated when whole blood lead is Ն2.25 ␮mol/L (45 ␮g/dL). The World Health Organization has defined whole blood lead concentrations Ͼ1.5 ␮mol/L (30 ␮g/dL) in adults as indicative of significant exposure and recommends chelation therapy when the whole blood lead concentration exceeds 3 ␮mol/L (60 ␮g/dL). As a result of these national and international guidelines, blood lead analysis has become the norm for identifying individuals with excessive body burden of lead. Blood collected …