Trumper¹⁰ state that 84% of lead ingested is excreted in the feces unabsorbed. The oral administration of edathamil calcium-disodium seems to promote not only the absorption of lead form the intestine which had never entered the blood stream but also the reabsorption of lead from the intestine which had gained access to it through the bile and other secretions. It would seem that any lead remaining in the feces of animals or humans exposed to lead poisoning to whom edathamil calcium-disodium has been given orally represents lead in excess of that combining with the chelate or lead in such a firm complex with other materials that it is not capable of combining with the chelate. It would appear that questions of this sort need further elucidation. The lead that has gained access to the blood stream is the lead that produces body injury, and, under the conditions of the experiments reported here, the lead in the urine is the major portion being eliminated from the body. The authors, therefore, agree with Canarow and Trumper¹⁰ in their statement that "the determination of the quantity (of lead) excreted in the feces is of little practical value."

An experiment of longer duration will draw a sharper focus on some of the points already discussed. For example, if a short-term administration of edathamil calcium-disodium for three weeks has produced no evidence of depletion of certain elements to the point of metabolic disturbance, might not longer periods of administration produce such a result? While the evidence we have presented does not favor the view that "trace metals may be made complex and result in damage to enzyme systems"²³ we advocate, and have followed, the intermittent treatment proposed by these authors and also by Rubin. In the future, our experiments will not only have a therapeutic holiday of two days each week but during these two days, a formula rich in minerals and vitamins will be administered. Holm and associates¹¹ favor intermittent dosage because of the time allowed for redistribution to occur between bone and soft tissue and, there may be added, for restoration of trace elements. Until further work shows this to be an unnecessary precaution because of the mixed diet being consumed, it may be advisable to use this procedure.

Edathamil calcium-disodium (Calcium Di-Sodium Versenate) in tablet form (250mg or 500mg per tablet) was given to two groups of battery-plant workers, five men in one group and seven in the other, over a period of two and three weeks. The edathamil calcium-disodium was given on the basis of 60mg per kilogram of body weight per day in divided doses for the first five days of each week.

Subjective symptoms of constipation, anorexia, and early fatigability cleared rapidly and, in most cases, were relieved completely.

The amount of lead in the blood showed a steady decline, but in only two instances did it reach normal levels. The actual decrease was from an average of 90.6_y to 70.4_y per 100cc. Body weight and red cell count were unaffected. Hemoglobin showed a slight but definite increase, from 81.6% to 87.2% (12.65 to 13.52gm, or 7%). Porphyinuria cleared entirely in three weeks, while stippling of red cells diminished from an average of 0.55% to 0.18%. Total lead in urine showed an average increase by the end of the first week from 280_y to 560_y per day and at the end of the third week to 690_y. Urine lead was increased from an average of 210_y to 430_y per liter.

Enough edathamil calcium-disodium is absorbed from the intestinal tract to cause a lowering of blood lead in three weeks and a decided increase in urinary lead, with no sign of any deleterious effect to the patients

*Rubin M. : Personal communication to the authors..