No health hazard from French tests

Press, Volume CX, Issue 32462, 24 November 1970, Page 16

No health hazard from French tests

French nuclear tests in the Pacific between May 16 and August 7 have slightly increased the amount of radioactive fall-out in New Zealand, but the levels are still only a small fraction of permissible levels for continuous consumption by the whole population, and do not constitute a health hazard.

This is the finding of the National Radiation Laboratory in Christchurch in its report for the second quarter of this year (April-June) and the results of Pacific area extended monitoring from July 27 to October 9. Routine monitoring showed np change in the deposition of strontium-90 in milk and in rain from the measurement in the first quarter. The level of caesium-137 in milk showed the expected seasonal decrease during the second quarter. The total beta activity showed some increase during the second quarter, the

: increase resulting from the higher levels of fresh fission products measured during June. No gamma ray radiation measurements exceeding the lowest reporting level had been reported from the Pacific Island monitoring stations, Increased levels of total beta activity in air filters occurred at all stations, between June 2 and June 4, about 18 days after the first nuclear test. The increased level had been maintained at all stations for samples to the end of September. As in the previous monitoring programmes in 1966-68, the levels at the New Zealand station have been lower than those at the Pacific Island stations. The report states that the pattern of increases, including the increase of iodine-131, was similar to those observed during the 1966, 1967 and 1968' series of atmospheric nuclear tests in the Pacific. A distinction is made between the levels of those radionuclides (that is, stron-tium-90, caesium-137, iodine--131 and, to a lesser extent, strontium-89) which' have a greater health hazard, and the total beta activity which although showing increases over limited periods, is of less significance in assessing health hazards. “The country-wide average level of strontium-90 in milk for the 12 months ending June, 1970, was about 2.5 per cent of the permissible level. The average level for caesium--137 in milk for the same period was 0.4 per cent of the permissible level.