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Perrault M. Truhaut R, Klotz B, Boudene C, Dreux C, Clavel B, Chain F. The effectiveness of CaEDTA, in occupational lead poisoning. Archiv des Maladies Professionelles de Medecine du Travail et de Securite Sociale. 1956; 17:423-429; discussion 470-472. (1702) [A case of acute occupational Pb poisoning is described. The man, who was employed in making storage batteries, had been handling for 1 yr a mixture containing Pb. He had paroxysms of abdominal pain and suffered from constipation, severe headaches and pains in the legs. There was an absence of coproporphyrinuria, but moderate anemia with very large number of stippled cells, and Pb content in blood of 115 mg/100 ml. CaEDTA was given by intravenous (iv) perfusions, with rapid removal of al pains and feeling of malaise. The perfusion was given over a period of 2-3 hr twice a day for 4 days and this course was repeated after an interval of 3 days. The headaches and joint pains persisted until the 2nd course. Stippled red cells soon disappeared from the blood and large amounts of Pb were excreted in the urine.
The action of CaEDTA is considered at length. It is a chelating agent which means that it captures Pb or other metals from the tissues, converting them into soluble and non-toxic salts; these salts are promptly carried to the kidneys to be excreted. Pb in the soft tissues and blood is first chelated; the Pb stored in the bones passes into the blood where it is chelated in turn. Metals which may be chelated are Ca, Cu, Pb, Hg, Fe and Cr. In order to avoid chelation of normal Ca, leading to hypocalcemia and tetany, the Ca salt is used instead of the Na salt. The Pb excreted in the urine may reach 4 mg in a child and 10 mg in an adult/day. The authors prefer iv administration, since the contents of the stomach may neutralize some of the chelating power before the drug reaches the blood. In the discussion, a plea is entered for oral administration in less acute cases to hospitalized patients or treated as ambulatory cases. Possibly EDTA might be used prophylactically for workers unavoidably exposed to a Pb hazard. EDTA is far less toxic than BAL; in fact, no injurious side effects have been seen. Its possible value in other conditions besides Pb poisoning has yet to be assessed. A successful ambulatory case is described.
In the discussion, Albahary discusses his experience with the drug. He agrees with the above authors that oral administration in milder cases would be more convenient, and raises the question of prophylactic treatment for heavily exposed workers. The optimum procedure still needs to be determined.

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