Use of 1080 poison defended

Press, 12 April 1978, Page 16

Use of 1080 poison defended

By

C. L. BATCHELER,

scientist at the Protection

Forestry Division of the Forest Research Institute, Ham.

Some of the comments made by a correspondent to “The Press” on the use of 1080 poison ar® grossly misleading. There is indeed no known specific antidote to 1080 poisoning, but this is a problem common to virtually all acute poisons used in vertebrate pest control, excepting perhaps anticoagulants such as warfarin. Most antidotal measures are designed to treat the symptoms, to sustain life in the victim until he has recovered. Monacetin, acetamide, alcohol and glucose have been shown to have beneficial antidotal effects in cases of 1080 poisoning, and, in a well-known case, were applied successfully to a 5-year-old girl (in San Diego, U.S.A.) who had eaten a large quantity , of 1080-treated rat bait and was in advanced coma before being placed under intensive medical care. She suffered no detectable after-effects of the poisoning. In lesser amounts than a lethal dose, 1080 is excreted quite rapidly through the urine. This evidence and the absence of any human deaths or illnesses attributable to 1080 in New Zealand, except for one suspected case of suicide, show that 1080 is a remarkably safe poison to use. It is far safer and freer of risks than arsenic, phosphorus or strychnine. It is now firmly established that 1080 degrades in the en-

vironment through bacterial and fungal action, and that there is no risk whatever of harmful residues accumulating in soil, water or through animal food chains. The great problem, of which both the Forest Service and the Agricultural Pest Destruction Board are well aware, is the accidental death of birds. This problem has been kept under general surveillance, and studied in detail in several situations, for over 20 years. It has been accepted that many birds are exposed to accidental death, particularly exotic species such as quail, blackbirds, chaffinches, but that few native birds were likely to be killed if prescribed bating procedures are rigorously applied. The general confidence that risks were slight blew up in our faces in the cold wet winter of 1966, and again last year, when Forest Service staff noted the death of birds (mostly introduced) at Taurewa and Karioi State Forests, and invited the Wildlife Service to monitor further trials, and advise on necessary modifications to procedures. Trials and investigations over the past two years have been greatly intensified, and several recommendations —■ on removing small fragments of bait, dyeing bait green, and avoiding the use of lures — are already being implemented. The effects of these

changes are being studied both through trials and monitoring of control operations. Death of birds has been recorded in public documents for many years, and no doubt will always occur if baits acceptable to both pests and desirable animals continue to be used. More selective baits and poisons are therefore being investigated. Nonetheless, we cannot trace any reliable records or accounts from critics of poisoning, nor from conservation organisations such as the Royal Forest and Bird Protection Society, which clearly indicate that current practices have jeopardised species or district populations of birds. Even in such a case as the poisoning of all or nearly all of the yellow-breasted tits in a 500-acre area of the Hokonui Range last winter, which was made public without delay, further work is necessary before we can deduce whether there were significant numbers of survivors in or adjacent to the poisoned area, and whether they will reoccupy the area within a few breeding seasons. Generally, the impression from such regions as the Ruahine Range, the Hokitika catchment and the Buller region, where several thousand tons of 1080-treated baits have been used for opossum control, is that recovery of the forest vegetation has been accompanied by vigorous increases of numbers of birds. Health of the habitat seems generally to be far more important for survival of birds than is death

of a proportion of them by poisoning. Regarding insects, we are similarly unaware of any significant effects on populations attributable to 1080 poisoning. This may be due to the sheer difficulty of perceiving or measuring such events, or more likely to the fact that most insects are inactive in winter (when most poisoning is done) and so are not at risk.

Your correspondent has made some obvious errors which should be corrected to avoid confusing your readers. He states that the Forest Service “continues to dump hundreds of tons of 1080 every year all over New Zealand.” In fact, the Forest Service over the past three years used record quantities of 1080. totalling 1.44 tonnes of 1080 per year, and the Agricultural Pests Board 1.19 tonnes per year, largely for control of tubercular opossum populations. The total used by all agencies for these three years was 7.87 tonnes. Over these same three years, about 20,000 tonnes of bait were used, over half of it in non-toxic prepoisoning feeding. About 112.000 tonnes of bait have been applied by aircraft in all animal pest control operations since 1951. Most of this work is far removed from being a “very long and expensive experiment.” It is a normal part of agricultural and forest pest management, which has long-since been judged to yield economic and environmental benefits which far outweigh the costs and risks involved.