[884] Med. Times and Gazette, June 1868, p. 658.
[885] Med. Times and Gazette, 1870, vol. i. p. 581.
[886] Atlas of Pathological Anatomy.
Metallic copper itself is not poisonous. A Mr. Charles Reed has published a letter in the Chemical News of Jan. 12, 1894, stating that he was, when a boy, wounded in the shin by a copper percussion-cap, and the cap remained in the tissues; it was removed from the shin after a sojourn thereof some twelve years; about the year 1873 he noticed that whenever a piece of clean iron or steel came in contact with his perspiration it was at once covered with a bright coating of copper, and this continued until the percussion-cap was removed. Presuming the truth of this, it shows conclusively that metallic copper deposited in the tissues is in itself not poisonous, and farther, that one method of elimination is by the skin. The experiments already cited throw doubt as to whether repeated small doses of copper taken for a long time produce in a scientific sense chronic poisoning; those which apparently support the view that there is such a thing as chronic poisoning by copper, have been produced by copper mixed with other metals; and there is the possibility that these cases are really due to lead or arsenic, and not to copper. The great use of late years of solutions of copper sulphate as a dressing to plants, for the purpose of preventing the ravages of various parasites, has provided, so far as animals are concerned, much material for the judgment of this question. Sheep have been fed with vines which have been treated with copper sulphate, oxen and pigs have consumed for a long time grass treated with a 3 per cent. of copper sulphate, without the least health disturbance. Mach[887] has fed cows with green food coppered up to 200 mgrms. of copper sulphate, without observing the slightest bad effect, for long periods of time; and Tschirch[888] summarises the evidence as to chronic poisoning as follows:—“So it appears the contention that there is no chronic poisoning in men or animals is at present uncontradicted; it is farther to be considered proved that the small amounts of copper naturally in food, or carefully introduced into food, are not injurious to the health of those that take such food, because the liver, kidneys, and other organs excrete the copper through the urine and bile, and prevent a pernicious accumulation.” At the same time, Tschirch does not consider the question is definitely settled; the experiments should, he thinks, have been continued not for months, but for years, to obtain a trustworthy judgment.
[887] Mach, Bericht über die Ergebnisse der im Jahre 1886 ausgeführten Versuche zur Bekämpfung der Peronospora, St. Michele, Tyrol.
[888] Op. cit.
It may also be remarked that, if we are to rely upon the separation of copper by the kidneys and the liver, those organs are presumed to be in a healthy state, which is not the case with a percentage of the population; to persons whose liver or kidneys are unsound, even the small amounts of copper found in “coppered” peas may act as a poison, and the experiments previously detailed throw no light upon the action of copper under such circumstances.