School of Advanced Nutritional and Medical Research

24 200
Heinrich Brieger

Chelating agents are used in chronic lead poisoning more than in any other occupational disease. Early recommendations of chelating drugs – for example, citrate¹ – had never found much favorable response. The danger of treating lead poisoning with 2,3-dimercaptopropanol (BAL), resulting from the instability of the complex in the milieu of the kidney, was emphasized shortly after the introduction of the drug.² However, it has been used frequently.

The introduction of the calcium chelate of disodium ethylenediaminetetraacetate (EDTA) has stimulated greatly this interest in specific therapy. Intravenous infusion of CaNa₂EDTA is, today, the therapy of choice in most cases of occupational chronic lead poisoning. Preliminary results of oral treatment with penicillamine^3,4 are encouraging, but it remains very doubtful whether it can, in its present form, replace treatment with CaNa₂EDTA.

A few statements based on personal experiences may be added to Dr. Rieders’ discussion of current concepts in the therapy of lead poisoning (p.143). While relapses occur rather frequently in children, they are rarely seen in adults. This difference may be explained by the fact that the adults are being treated more intensively and that they return more regularly for re-examination of lead levels in blood and/or urine. The application of a single intravenous infusion of CaNa₂EDTA for diagnostic purposes, as first suggested by Rieders,⁵ has been criticized by Bell.⁶ We have made use of this method in a large number of cases and are convinced that it is a very useful procedure to ascertain excess lead accumulation. The ineffectiveness of the oral application of CaNa₂EDTA has been explained and emphasized. It is true that a chelating agent which could be taken orally and could eliminate lead effectively and safely would be of great importance in the treatment of lead poisoning in children. However, it is questionable whether such a drug is highly desirable form the viewpoint of protecting exposed workers from excess absorption of lead. It is unknown whether the administration of chelating agents over very long periods of time is a harmless procedure. Certainly, the indiscriminate prophylactic use of chelating agents may prevent essential activities in the field of industrial hygiene and medicine. Johnstone⁷ has exemplified Kehoe’s early warning⁸ by reporting that an industrial plant in Los Angeles had stacked its shelves with CaNa₂EDTA instead of inaugurating a control program for reduction of atmospheric levels of lead. [Emphasis added.] this situation brings to mind that, in the past, milk – through contraindicated in cases of excess lead absorption and lead poisoning – had been given with the same "side effects".

*Editor’s Note: also discussed by Dr. Rieders on page 143.