1 Johns Hopkins University, School of Medicine, Associate Chief Pediatrician, Baltimore City Hospitals, Baltimore, Maryland
If physicians are to deal effectively with the biologic effects of ubiquitous chemical agents such as lead, a working knowledge of the pertinent time-dose-response relationships is essential. Lead is currently considered a nonessential trace element and is detectable in minute amounts in food and water and in the blood, tissues, and excreta of virtually all healthy persons. Apparently, the biologic effects of the usual daily intake from uncontaminated food and water (approximately 0.2 to 0.3 mg lead/day in adults) is negligible, so that this small "dose" of lead has no known adverse effect on the health of people, but as the chronic "dose" of lead increases, adverse responses of increasing severity become evident.