Recent Advances in Fumigation of Ships

THE problem of rat eradication on ships has been intensively 1studied in this country principally by Creel and Simpson, ' Grubbs and Holsendorf,2 Akin and Sherrard,3 and Williams.4 During the past 3 years, the whole subject has been under review by a commission of the League of Nations cooperating with the Office Internationale d'Hygiene Publique. As a part of their program, systematic studies of fumigation and directly related procedures were carried out at the New York Quarantine Station. These studies form the basis for the present paper. From data available at the beginning of this study, it was apparent that: (1) only about 10 per cent of ships were persistently and heavily rat-infested, the other 90 per cent exhibiting variable infestation or complete freedom from rats, and (2) that infestation was largely dependent on the extent and depth of rat harborages, maintenance of large colonies being due principally to breeding on board. These conclusions pointed the wav to two distinct lines for investigation. One pursued by Akin and Sherrard6 was the possi-bility of segregating ships according to degree of rat infestation, the other to develop more effective fumigation methods for treatment of infested ships. The latter study has taken much time and physical labor. It has involved an intimate and extended study of the details of ship construction, as well as the development of improved methods of introducing fumigating gases. The fumigants in general use on ships today are hydrocyanic acid and sulphur dioxide. The modern cyanide fumigants are liquid [895] AMERICAN JOURNAL OF PUBLIC HEALTH HCN and Zyklon. The possibilities of sulphur dioxide have not yet been fully investigated and it will be only incidentally referred to in this paper. Liquid HCN is packed in heavy steel cylinders, from which, for fumigation purposes, it is sprayed by air pressure. The liquid is the most effective and adaptable form of HCN, but requires the most apparatus. It is also the most dangerous to handle. Zyklon and Zyklon discoids are liquid HCN absorbed in inert material-kieselguhr and wood fiber discs respectively. It is packed in heavy metal cans and used by spraying on the floor

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