Contamination from tests at minimum detectable

Press, 16 September 1976, Page 18

Contamination from tests at minimum detectable

Parliamentary reporter Wellington

Short-lived contamination of air and rainwater which was still detectable early in 1975 after the 1974 atmospheric nuclear tests in the Pacific decreased gradually, until at mid-year and after levels were at or below the minimum detectable both in New Zealand and the Pacific area.

This information is given in the annual report of the Health Department, tabled in Parliament this week. “France ended her atmospheric nuclear weapons testing in 1974 and started underground tests in 1975,” the report said. “The National Radiation Laboratory consequently reorganised its monitoring service for the Pacific Islands area. The purpose of this continuous monitoring in the Pacific area is to detect any venting of fission products from underground tests. “The levels of long-lived strontium 90 in rain and milk (including caesium 137) continued to remain at the very low values which had been measured during the previous two years,” the report said. The programme ended by measuring radionuclides in the 118 human bone samples obtained since 1976. Results showed that the average long-term dose to bone from strontium 90 was less than 2 per cent of that from the “average” natural radi-

ation environment. Naturally occurring boneseeking radium 226 and lead 210, also measured in these samples, gave a dose about 12 times greater than strontium 90.

In co-operation with the Commission for the Environment and other organisations, the department had been involved in the evaluation of air pollution aspects of major industrial developments, said the report. This had led to the concept of the best practical means of control of air pollution being extended to the “best praticable environmental option.” As well as the monitoring of individual industries, it was necessary to establish the pattern and extent of urban pollution throughout New Zealand. This had been concentrated in Auckland and Christchurch which represented the extremes of two patterns of pollution found in New Zealand. The work which had been carried out had shown either a satisfactory level of the conventional combustion pollutants, sulphur dioxide and smoke, or a decline over recent years. In the South Island, this decline seemed now to have halted, said the report. “In an effort to imp'rove air quality in Christchurch, the city has sought to establish the first clean-air zone under the legislation. This sets high requirements on in-

dustry and can also apply smoke control to domestic premises.” There had been a significant reduction in deaths from tuberculosis, the 1950-54 rate being more than seven times higher than that for 1970-74, the report said. The rate for all other infectious and parasitic diseases had also fallen. In 1950-54, it stood at 11.8 per 100,000 mean population, more than twice as high as the 1970-74 level of 5.5. The rates for active rheumatic fever and chronic rheumatic heart disease decreased steadily from 13.9 in 1950-54 to 6 in 1970-74, the report said.

Other forms of heart disease and hypertension, which included coronary heart disease, were the principal cause of death. Although the rates of coronary heart disease had risen in recent years, this reflected in part a change in terminology as well as a true increase in incidence. Nevertheless, taken as a group, the rates for other forms of heart disease and hypertension had decreased over the period reviewed. The rates for motorvehicle accidents showed a considerable increase, from 14.8 in 1950-54 to 24.7 in 1970-74, the report said, but the rates for other accidental and violent deaths, for suicides, and for homicides, were stable throughout the period.