CONTAMINATION OF N.Z. “UNLIKELY”

Press, Volume CVI, Issue 31077, 4 June 1966, Page 3

CONTAMINATION OF N.Z. “UNLIKELY”

Scientists’ Assessment Of French Tests

(New Zealand Press Association)

WELLINGTON, June 3.

It is “extremely unlikely” New Zealand or its island territories will experience any significant radioactive contamination from the proposed French nuclear tests in the Pacific, according to a report by three New Zealand scientists and tabled in Parliament today.

The French tests would add only fractionally—but not significantly—to the long-lived fall-out in New Zealand or other Pacific territories, they said.

The report , was made by Dr. J. F. Gabites, director of meteorological service, Mr T. A. Rafter, director of the Institute of Nuclear Science, and Mr G. E. Roth, director of the National Radiation Laboratory.

They concluded that, in spite of contamination from the French tests, the general level of contamination in the Southern Hemisphere would remain below that in the Northern Hemisphere.

The French tests will be held in the vicinity of Mururoa atoll in the Tuamotu group.

“Although it is not possible to give an assurance that no contamination by fresh-fission products will occur an any Pacific island with which New Zealand is associated, any significant contamination can result only from a series of unlikely occurrences which make the event extremely improbable,” said the report. “For New Zealand, the chance of significant levels of contamination being reached is even more unlikely than for the islands in the Pacific."

The report said most of the debris from the French tests would fall into the sea.

“The French tests are likely to cause heavily-contaminated areas in the sea up to a few hundred miles from the test site with consequential local contamination of fish and sea food.” But there was only an “extremely remote chance” of the French tests significantly polluting the sea food in any island with which New Zealand was closely associated. “Although it is extremely unlikely significant amounts of fall-out will reach any Pacific island with which New Zealand is associated, a remote possibility exists that

measurable amounts of fallout could be deposited with rain.”

Check In Islands

Because of this instruments for the direct measurement of resulting radiation were being provided for use at Rarotonga, Mangaia, Aitutake, Penrhyn (Cook Islands), Tonga, Niue and Samoa. However, protective measures would only be taken if justified by excessive radiation levels being reached. To detect even slight traces of radioactivity which may reach the islands, rain-water collectors were being placed in all the areas mentioned, as well as at Raoul Island, Funafuti, Tarawa and Nandi. Air samplers would be operated at Rarotonga and Nandi. These pumped air through a filter which was sent to the National Radiation Laboratory for measurement of radioactivity.

“It could happen that New Zealand would receive fallout which had travelled round the earth before it reaches the islands closer to the test site but because of the time elapsed its radioactivity would be low,” said the report. The National Radiation Laboratory’s monitoring network will be augmented by

the human thyroid and presents a short-term hazard through the contamination of food, such as fresh milk produced by animals grazing on contaminated pastures].

Lesser Hazard Current levels of caesium--137 in New Zealand milk were less than 1 per cent of the permissible level for the whole population and it presented a much smaller health hazard than strontium-90. [Caesium-137, when taken into the human body, is distributed fairly uniformly].

measuring the filters from established air samplers at Auckland and Christchurch daily and using another sampler at Wellington. Measuring the strontium-89 content of rain collected by the established network of stations the presence of short-lived strontium-89 would indicate the collection of relatively fresh - fission products and making additional fresh milk collections at Auckland, New Plymouth, Wellington, Greymouth, Christchurch and Dunedin to check for the presence of iodine-131. Between 1945 and 1962 more than 423 nuclear weapons had been exploded. Since 1957, the Health Department had been monitoring environmental radioactive contamination from stronium--90, iodine-131 and caesium--137.

“If it is remembered that millions of people have lived for countless generations in areas where naturally-occur-ring radiation is at a level several times that of the average natural radiation not just twice the average level for a few months the hazard from existing fall-out contamination will be seen in its true perspective,” the report said.

The report said the allstation average of strontium--90 for New Zealand milk for the year ended December, 1965, was 4.5 per cent of the “permissible level” for the whole population. [Strontium-90’s chemical behaviour is similar to that of calcium and is deposited on the human bone like calcium].

Checks for iodine-131 were made in milk in New Zealand and Australia during the nuclear tests in the Pacific in 1962. In Tasmania, the average level for the year was 0.5 per cent of the permissible level and the only New Zealand test indicated an average level for the country below that for Tasmania. [lodine-131 concentrates in