74.

Gervais MJ. The medical prevention of lead poisoning in an electrolytic zinc factory. Montpellier Medical. 1962; 61:12-27 (Jan.). (2401) [The author describes his experience in the surveillance of workers of a Zn extraction plant at Viviez. This is the only plant in France in which Zn is extracted electrolytically, employing 1000 workers, and which processes 40% of the total Zn produced in France. The sources of hazards of Pb intoxication in this process are caused by the presence of 2-3% Pb in the ore as impurity, and by the reaction of sulfuric acid on the Pb-containing mineral in the industrial process.
In discussing the medical program, first outlined are the various factors (advanced age, alcoholism, poor hygiene, systemic and particularly renal deficiencies) that may influence the individual susceptibility of the worker to Pb poisoning. According to French regulations, in jobs involving Pb risk, no men should be hired who are predisposed to Pb poisoning due to renal and liver diseases, arterial hypertension, and disorders of the blood and central or peripheral nervous system. Complete pre-employment examinations (including x-rays) are done at Viviez. In the periodic examinations, the frequency of which, a prescribed by law, the author considers to be the minimum, the surveillance of the renal condition is given particular attention. As a result of these examinations, workers are placed in 3 categories: those to be removed from exposure, those to be watched, normal subjects. The principal signs and symptoms of Pb poisoning as reported in the literature, are discussed in detail.
In agreement with other authors, the Pb line is absent in frank Pb intoxication, while it seems sometimes to be present in cases without any pathologic signs. The author has seen it rarely, probably because of better preventive measures and better oral hygiene among workers. He has never seen Gubler's tumor and parotid hypertrophy. Concerning the neurologic signs, the ones to be given particular attention are latent pareses of finger, especially of extensors, and muscular cramps and myalgias which occur frequently in Pb-exposed workers and are often improperly designated as rheumatism. True Pb colic is encountered more rarely now than earlier reported; in the past 2 yr the author has seen no typical case of it, although some of the newer workers exhibited transient attacks. Caution is expressed concerning the diagnosis of anemia by stating that this can be done only on a basis of knowledge of pre-exposure values rather than by accepting an absolute number of red cells and hemoglobin values. The presence of basophilic stippling of erythrocytes is considered as the most important indication of Pb intoxication in spite of the limitations of this test.
The leukocytic formula is not considered to be of much value as a test. The author considers the urinary coproporphyrin test to be one easily made on large numbers of workers, and does it routinely on all workers. Because of the variations encountered in blood-Pb levels in relation to current occupational exposure to Pb, and difficulty in analysis, this test is believed to be of little practical interest in industry except from the point of view of etiology of the disease and in medicolegal cases. Urinary Pb determination is of still less practical interest because it is influenced by the condition of the kidney, by the diet, and because Pb fixed in tissues is eliminated only periodically. For these reasons and because of difficulties in analysis, it is not done at Viviez, although interest in the EDTA-challenge test is expressed. In spite of its limitations, the blood-urea test is considered to give indication of low tolerance to Pb; also that the worker is to be watched and possibly removed from exposure.
Following a review of the literature of the use of EDTA in the treatment of Pb poisoning from which the author concluded that it is most effective "and entirely devoid of toxicity," he has used this drug in the plants of Viviez since 1958 on 20 workers at doses of 4-6 tablets of 0.25 g daily, either 5 days per week or continuously for 20-30 days. At the beginning and end of each treatment a differential blood count, blood urea and albuminuria tests were done. Urinary coproporphyrin was determined to follow the course of treatment.]

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