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adequate precautionary measures should be taken at all stages from the manufacture of
the fumigant to the declaration of freedom from danger at the conclusion of operations.
The precautionary measures and the additional precautions for the treatments of ships
which are to be followed are laid down in a Home Office Pamphlet dated 1960.
The fumigation of ships by methyl bromide, usually for disinsection purposes, occurs
only occasionally in the Port of London.
The exposure to the gas depends on the concentration and on the period and purpose
of the exposure. For example in the case of a ship with completely empty holds, 12 ozs
of liquid per 1,000 cu. ft. for 12 hours would eradicate a rodent infestation in the holds,
whereas a minimum concentration of 32 ozs per 1,000 cu. ft. for 24 hours would be
required in the case of Khapra beetle infestation.
The following are the names of the firms approved for carrying out the deratting of ships:—
Contra-Pest Service Ltd.
Rentokil Laboratories Ltd.
(iv) Progress in Rat Proofing of Ships
Lloyds Register of Shipping Statistical Tables 1970, show the ocean fleets of the World to
be comparatively new, that is 57% (per cent) are less than 10 years old. The introduction of rat
proofing measures in ships first adopted by the Maritime nations some twenty years ago has
become standard practice over the years and rat proofing of the vulnerable parts of the ship, for
example the provision store room, is now almost always present. When the rat proofing is found to
be defective, usually through non-replacement after refit, every endeavour is made to have it made
good before the vessel sails.
Rodent control measures on lighters have been carried out successfully during the past year.
Of the 2,649 lighters inspected for rodent indications, 1,525 were inspected on the Upper and
Middle River Districts, the remaining 1,124 inspections being carried out in the respective dock
groups. It will be observed that there has been a decrease in the number of inspections carried
out on the Upper and Middle River Districts, this was due to the fact that as a result of the sale
of the "Frederick Whittingham" in November 1969 the Technical Assistant now shares the m.v.
"Alfred Roach" with the Port Health Inspector and the time spent on lighter inspections is
therefore curtailed.
It will be noted by referring to the attached table that the degree of infestation is still
decreasing. There were 81 lighters deratted last year with an average of 2.9 rats recovered per
lighter treated which is the lowest figure on record.
Importance of Rodent Control on Lighters — no change.
Economic Burden — no change.
Rat Suppresive Measures
Fumigation, poisoning and trapping — no change.
Cleanliness and hygiene — no change.
Harbourage and rat-proofing — no change.
The methods of deratting employed throughout the year were:-
The method of treatment is determined by the condition and degree of infestation of the
lighter at the time of inspection.
In view of the fact that in nearly all instances there is a residue of water and foodstuffs in
lighters when empty, it has been found from past experience that if treatment is required, it is
far more efficient to fumigate the lighter than to use a rodenticide.
During the year, eleven of the rats recovered from treated lighters were sent to the Public
Health Laboratory, County Hall for routine bacteriological examination and on each occasion
Pasteurella pestis was not isolated.
RODENT CONTROL MEASURES CARRIED OUT ON LIGHTERS
Fumigants
1. Sulphur Dioxide
2. Methyl Bromide
Rodenticid.es
Sodium mono-fluoroacetate
Multiple dose poisons.
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