Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Patent
1997-03-20
1999-12-14
Dees, Jose G.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
424607, 514526, A01N 2500, A01N 5924, A01N 3734
Patent
active
060013834
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This Appln is a 371 of PCT/AU95/00409 filed Jul. 5, 1995. This invention concerns fumigants. More particularly, it concerns and fumigants as gas, or in solution which include the cyanogen (C.sub.2 N.sub.2), and methods of fumigation using such gaseous and dissolved fumigants.
BACKGROUND TO THE INVENTION
Fumigants are widely used for the disinfestation, and protection against infestation, that is usually required to protect particulate commodities (such as grain) and other stored produce (including durable and perishable foodstuffs), porous bulk materials (for example, soil or timber) and spaces (typically, empty buildings). An ideal fumigant should be toxic to insects, mites, nematodes, bacteria, fungi and their spores, viruses and moulds and other pest biota. It should be effective in low concentrations. It should ideally have a low absorption by materials in the fumigated region. It should have a low mammalian chronic toxicity and leave either no residue or an inert residue. In addition, the ideal fumigant should present no difficulties as far as safe handling is concerned, and it should not adversely affect the commodity or space that is being fumigated.
No fumigant meets all of these "ideal" criteria. The two fumigants most commonly used in the fumigation of grain, other particulate materials, fruit and timer are phosphine and methyl bromide, although carbonyl sulphide has recently been proposed as an alternative to these fumigants (see the specification of International patent application No. PCT/AU93/00018, which is WIP0 Publication No. 93/13659).
Phosphine is the preferred fumigant for grain stores and the like because it is effective against grain pest and leaves little residue (which is essentially a harmless phosphate). However, phosphine is spontaneously combustible when its concentration exceeds a relatively low value, and is unable to kill all stages of insects in a short period when used at acceptable concentrations.
Methyl bromide is more toxic to grain pests than phosphine when used for short periods of fumigation, but phosphine is more toxic to grain pests when long term fumigation is effected. Methyl bromide has a lower flammability than phosphine, but recent work has shown that methyl bromide depletes the ozone layer. Thus the use of methyl bromide as a fumigant is currently being phased out, following the Montreal protocol.
Carbonyl sulphide is currently undergoing extensive testing, and has not yet been approved for use as a fumigant, despite some clear advantages over both methyl bromide and phosphine. Other fumigants that have been used against grain pests include acrylonitrile, carbon disulphide, carbon tetrachloride, chloropicrin, ethylene dibromide, ethylene dichloride, ethylene oxide, hydrogen cyanide and sulphuryl fluoride. It will be noted that a halogen is present in many of these "conventional" fumigants, none of which has the "ideal" fumigant properties.
For many years, there has been a constant seeking of new fumigants and there is no doubt that the quest for improved fumigants will continue.
SUMMARY OF THE INVENTION
The present invention seeks to provide a new fumigant that has properties which make it a viable alternative to the conventional fumigants, particularly in the control of insects, mites, nematodes, fungi and their spores, bacteria, viruses, moulds and other pest biota.
In one broad form, the present invention provides a fumigant comprising cyanogen (C.sub.2 N.sub.2) (as herein defined), in solution or in association with a carrier gas, wherein the concentration of cyanogen is in the range from 0.01 mg L.sup.-1 to to about 160 mg L.sup.-1.
Preferably, the carrier gas is an inert gas and also preferably the carrier gas has a low oxygen concentration.
In a preferred embodiment of the invention the carrier gas includes carbon dioxide.
According to a still further embodiment of the invention the fumigant is in solution, preferably an aqueous solution.
In a further broad form, the present invention provides a method of fumigation, comprising ap
REFERENCES:
patent: 3535076 (1970-10-01), Fahnenstich et al.
The Merck Index, 10th Ed., Pub. 1983, p. 385, Entry 2686.
Desmarchelier Frances James Michael
O'Brien, deceased Ian G.
Yonglin Ren
Commonwealth Scientific and Industrial Research Organisation
Dees Jos,e G.
Pryor Alton
University of Canberra
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