Chronic industrial exposure to lead in 63 subjects. II. Evaluation of chelation therapy.

Efficacy of chelation therapy with intravenous calcium disodium edetate, oral Ca EDTA, and oral penicillamine was tested in 63 subjects with chronic minimal industrial exposure to lead. All three agents increased the urinary lead excretion. The effect was greatest with intravenous Ca EDTA, next with oral penicillamine and least with oral Ca EDTA. Symptoms, particularly colicky abdominal pain, improved during the period of chelation therapy. Anaemic subjects showed improvements in haematological parameters. It is recommended that subjects with chronic minimal industrial exposure to lead receive chelation therapy. The relative merits of the three agents are discussed.

Chronic industrial exposure to lead in 63 subjects. I. Clinical and erythrokinetic findings.

Clinical, biochemical, haematological and erythrokinetic studies were performed on 63 adult males with prolonged lead exposure. Their most common symptoms and findings were abdominal pain (62%), gingival lead lines (48%), headache and/or dizziness (33%), muscle cramps (32%), anaemia (19%), and fatigue (18%). Colicky abdominal pain (27%) and gingival lead lines correlated with urinary lead excretion. Anaemia was mild, but more frequent in the subjects with the greatest urinary lead excretion. Other associated findings were: higher reticulocyte counts and more basophilic stippling of the RBCs, more sideroblasts and greater erythroid hyperplasia of the bone marrow, more reduction in 51Cr-tagged RBC survival time, smaller RBC mass, a more rapid plasma iron clearance, a greater plasma iron turnover and greater utilization of 59Fe in subjects with urinary lead excretion of greater than 100 microng/day in comparison with the remainder and normal controls. These findings suggest that minimal chronic exposure to lead causes an increased haemolysis with resulting increased production of erythrocytes.