Three hundred micrograms of elemental lead is considered to be the maximum daily permissible intake (DPI) from all sources for children. As the average intake increases above this value, the entire amount cannot be excreted and accumulation in the body begins. This will increase progressively as long as undue ingestion continues. The DPI has been established on the basis of levels of lead in the blood of nonexposed and exposed children including those with frank lead poisoning; results of experimental lead ingestion by adults; fecal lead output in children; initial biologic effects of increased lead intake; rates of increase in lead in the blood of exposed children, and sequelae of lead poisoning. The aim of the DPI is prevention of disease and preservation of health in children.
King BG. Maximum Daily Intake of Lead Without Excessive Body Lead-Burden in Children. Am J Dis Child. 1971;122(4):337-340. doi:10.1001/archpedi.1971.02110040121011