Biomedical subjects
J A Reissland
Publications and source records attributed to J A Reissland.
The assessment of late effects on a population exposed to activity released into the environment.
The long term effects resulting from an accidental release of radioactive material are considered. The magnitude of the release is defined in terms of the percentage of total excess cancer mortalities relative to the number that would have been expected in the same population had the accident not occurred. The increased risk is expressed as the change in life expectancy as a function of age at the time of exposure. Loss of life-years per person is calculated for an increase of 0.1, 1, 10 and 100% in cancer deaths and are quoted for ages 1, 10, 20, 30, 40 and 50 years at time of exposure. The variation of the effect with age may be summarised using the ratio of the reduced life expectancy to the reduced life expectancy for a person aged zero at the time of the accident. For the initial external dose, this ratio exhibits a linear decrease up to about age 45 years at the rate of about 2% per year so, for example, the increased risk for a person aged 40 at exposure is 20% of the increased risk of a child just born. Similar estimates are made for a dose which is prolonged over 50 years, to represent doses from internally incorporated radionuclides.
The observation and analysis of cancer deaths among classified radiation workers.
The extent to which occupational radiation exposure contributes to cancer mortality is an influence on future world energy policy. It is also a factor in deciding the level of expenditure to reduce radiation levels experienced by workers. Here we discuss some of the difficulties in analysing the situation and present the results of some calculations which estimate the expected age-specific radiation mortalities from all inducible cancers and also from leukaemia separately. Using a high value for the average occupational exposure and a conservative estimate of the associated risk, we find that a survey of mortality among radiation workers must run over many years before sufficient data would be accumulated to resolve the effects of radiation-induced neoplasms from those arising from other causes. We show the advisability of determining the cause of death both of persons who remain employed in the industry and all for only a short time. Our estimates are based on maintenance of an occupationally exposed dose of one rad per person per year during the period of the survey which may extend over several decades. However, scaling of the estimates to any other exposure rates is easily performed. We also give estimates of the lowest risk coefficients detectable in a given observation time. Since for a work force of 3000 these lowest detectable values are an order of magnitude larger than those expected, it is clear that only a national or international survey can produce data adequate for even modest objectives.