[23] Bikler: Arch. für Augenheilk., b. xl., 1900.
[24] Weber: Thèse de Paris, 1884.
[25] Folker: Ibid.
[26] Lockhart Gibson: Ibid.
CHAPTER X
CHEMICAL INVESTIGATIONS
Very great assistance is afforded by chemical and histological diagnosis in the determination of cases of lead poisoning, especially when the case is likely to involve proceedings under the Workmen’s Compensation Act. In addition, a large amount of information is afforded to the certifying or appointed surgeon and the medical practitioner by adoption of certain easily carried out methods of diagnosis. It will be our purpose in the present chapter to describe as far as possible methods by which chemical or other investigation of a case of lead poisoning can be pursued, and the clinical methods of diagnosis which are applied in ordinary routine.
The majority of the methods described, especially the chemical investigation of material obtained from alleged fatal lead poisoning for the purpose of determining the presence or absence of lead, the histological examination of such tissues, and the examination quantitatively of excretions for lead, are processes which can only be carried out in a fully equipped laboratory, and certainly do not belong to the ordinary routine of medical work. The medical practitioner cannot be expected in the ordinary course of his routine work to examine blood-films for basophile staining or to make differential blood-counts. Especially is this the case in the routine examination of large numbers of factory hands. Further, many of the processes involved in either the chemical or histological examination of the tissues require so much special apparatus, without which such work cannot be undertaken, that the mere cost of the necessary instruments precludes the investigation being carried on except in special laboratories. At the same time, our purpose is to point out how additional methods of research may be made use of in obscure cases, and how recourse should be had to a well-equipped laboratory in doubtful cases. Further, the coroner, when ordering a post-mortem examination, may ask for a histological and chemical examination.
Methods of Chemical Diagnosis.
—The presence of lead may require to be determined qualitatively and quantitatively, and the procedure may differ slightly as to which process it is necessary to adopt. The quantitative determination of the amount of lead present in organs or excretions of the body is of far more importance than the estimation or determination of the fact of its presence. We have already referred to the work of Gautier[1], who has found lead present in the tissue of normal persons with such constancy that French observers, at any rate, now speak of “normal lead,” to distinguish it from lead which may be found in pathological conditions. There is, however, little doubt that the quantity of lead existing in the human body is exceedingly small. It is possible, with certain refined methods of chemical examination, that qualitative traces of this substance might be found. On the other hand, the methods of determination of lead are some of the most difficult in toxicological analyses, on account of the presence of other metals, particularly iron, which are exceedingly difficult to get rid of, and may easily lead to errors.