Report of the Medical Officer of Health / Municipality of Colombo.

  • Colombo (Sri Lanka). Public Health Department.
Date:
[1930]
Catalogue details

Licence: Public Domain Mark

Credit: Report of the Medical Officer of Health / Municipality of Colombo. Source: Wellcome Collection.

    107/124 (page 81)
    V.—The Practice of Cyanide Fumigation. 1.—General uses of Cyanide Fumigation. Coquillet, an officer of the United States Department of Agriculture, appears to have been the first to employ hydrogen cyanide gas for fumigation purposes, viz., the destruction of the scale insect pest of citrus tiees, in 1886. As already indicated, its use for this purpose is now (,reneral wherever orange orchards are found. The trees are tented, liquid HCN liberated beneath the tent or calcium cyanide dust blown in. Every year cyanide fumigation is increasingly applied to economic purposes, c.g., green house fumigation, disinfestation of wheat from weevils, “bran bugs,” and other economic pests of stored grain, destruction of burrowing animals, rabbits, moles, and field rodents generally, termites, land crabs, locusts, wireworms in soil. The cyanide fumigation of ships, lighters, shore warehouses and other compartments, and in tunnels, and con\eyors for the destruction of rats and their fleas requires special consideration for purposes of plague prevention. 2.—Fumigation of Ships. Sulphur dioxide gas generated from a Clayton apparatus is the chemical most commonly •employed by port authorities for ship fumigation, but it is gradually being superseded for this purpose by the more efficient, if more dangerous, cyanide gases. The United States Quarantine authorities were the pioneers of cyanide fumigation of ships. The gas was first authorized in the United States Quarantine Regulations as a fumigant in 1910 and was used for anti-plague purposes in Porto Rico in 1912, and by the Cuban authorities at Havana in 1914. Since the outbreak of human plague at Naples in 1901 and the subsequent discovery of an extensive epizootic among the rats of the docks at Punto Franco, the Italian authorities have devoted much attention to de-ratisation of warehouses and ships. According to Lutrario (1928) the proportion of ships fumigated with HCN in Italy has constantly increased since 1921 (26 percent.) and in 1926, 43 per cent, of the total were so fumigated, sulphur dioxide being employed for the remainder. HCN gas is being increasingly used for ship fumigation at Spanish and South American ports. A great impetus to cyanide fumigation in Great Britain was given by the issue of the United States Quarantine Regulations of 1920 which required that all vessels engaged in trade with foreign ports should be fumigated not less than once in every six months simultaneously in all parts, thus complying with the recommendation to this effect of the International Sanitary Con¬ vention of 1912 (ratified in October 1920). British shipping companies trading with the United States commenced experiments on ship fumigation with hydrogen cyanide gas, which were watched on behalf of the Ministry of Health by Messrs. Stock and Monier-Williams, to whose illuminating report the writer is parti¬ cularly indebted for information on all aspects of ship fumigation. Some of the largest Trans-Atlantic liners afloat, including the ss. “Mauretania” 30,700 tons, and the ss. “ Berengaria ” 52,700 tons have been succesfully fumigated with hydrocyanic acid gas. Fumigating operations of this magnitude, however, require elaborate preparations, while as Col. Reece has pointed out, the volume of poison gas disengaged in fumigating a single one of these gigantic vessels exceeds that liberated in any gas attack in the Great War. The art and science of ship fumigation has been brought to the highest pitch of develop¬ ment by the New York Quarantine authorities. Attention is directed to the series of papers by Grubbs and Holsendorf, Akin and Sherrard (1928), and the note to the Committee of the Office International d’Hygiene Publique by Taliaferro Clark (May, 1928). According to the latter during the period July 1, 1926 to June 30, 1927, 20,284 vessels from foreign ports reached the United States and were submitted to inspection by the quarantine authorities. Of this number, 5,114 were fumigated for the destruction of rats. Nearly all these fumigations were effected after discharge of the cargo from the ship. 3,317 of these fumigations were carried out with hydro¬ cyanic acid gas and the remaining 1,797 by means of sulphur dioxide gas. Formerly before the introduction of improved measures for the rat-proofing of vessels 65 per cent, of the rat infestation was found in the holds and 35 per cent, in the superstructures of the ship. Now the position is entirely reversed, only 30 per cent, of the rats are found in the holds, irrespective of the nature of the cargo. It will be appreciated that the problem of fumigating superstructures differs fundamentally from that of dealing with holds. The former is not affected by the state of the cargo.. The effective fumigation of holds when full of cargo is difficult and is usually only attempted in the case of ships definitely known to be plague infected at the time ; more commonly the cargo of such ships is discharged into lighters by stages and fumigation repeated after each stage, finally the cargo itself in the lighters is re-fumigated. The difficulty is to secure effectiv e circulation of the cyanide gas and to remove it from pockets of cargo after fumigation. In ordinary practice the cargo is discharged from the hold into lighters before fumigation commences, and under these conditions the proportion of rats killed to those recovered by subse¬ quent trapping is very high. The question of the effective fumigation of loaded ships with HCN gas is now engaging the attention of a Fumigation Commission of the League of Nations. In America liquid hydrocyanic acid in cylinders seems to be the product most favoured for the fumigation of the holds of large ships at the chief quarantine stations, Zyklon B. or HCN discoids being used for the superstructure and for the whole ship at smaller stations.