In January and February of 1971, a total of 81 children in two Cincinnati central city communities were screened for elevated blood lead levels. Seventeen of these children had blood lead levels over 40μg/100 gm of whole blood analyzed by the dithizone method. The absence of symptoms or signs of hematologic and radiographic changes emphasized that dependence on these is insufficient in identifying children with increased lead burdens. Lead was identified by an x-ray fluorescence analyzer in all the houses in which the screened children lived. Exterior surfaces had higher lead content than interior doors and doorways, which in turn had more lead content than other interior surfaces.
Reece RM, Reed AJ, Clark CS, Angoff R, Casey KR, Challop RS, McCabe EA. Elevated Blood Lead Levels and the in Situ Analysis of Wall Paint by X-Ray Fluorescence. Am J Dis Child. 1972;124(4):500-502. doi:10.1001/archpedi.1972.02110160038003