Transfer of 137Cs from Chernobyl debris and nuclear weapons fallout to different Swedish population groups

Abstract

-Data from measurements on the body burden of 134 Cs, 137 Cs and 40 K in various Swedish populations between 1959 and 2001 has been compiled into a national database. The compilation is a co-operation between the Departments of Radiation Physics in Malmö and Göteborg, the National Radiation Protection Authority (SSI) and the Swedish Defense Research Agency (FOI). In a previous study the effective ecological half time and the associated effective dose to various Swedish populations due to internal contamination of 134 Cs and 137 Cs have been assessed using the database. In this study values of human body burden have been combined with data on the local and regional ground deposition of fallout from nuclear weapons tests (only 137 Cs) and Chernobyl debris (both 134 Cs and 137 Cs), which have enabled estimates of the radioecological transfer in the studied populations.The assessment of the database shows that the transfer of radiocesium from Chernobyl fallout to humans varies considerably between various populations in Sweden. In terms of committed effective dose over a 70 y period from internal contamination per unit activity deposition, the general (predominantly urban) Swedish population obtains 20-30 µSv/kBq m -2 . Four categories of populations exhibit higher radioecological transfer than the general population; i.) reindeer herders (~700 µSv/kBq m -2 ), ii.) hunters in the counties dominated by forest vegetation (~100 µSv/kBq m -2 ), iii.) rural non-farming populations living in sub-arctic areas (40-150 µSv/kBq m -2 ), and iv.) farmers (~50 µSv/kBq m -2 ). Two important factors determine the aggregate transfer from ground deposition to man; i.) dietary habits (intakes of foodstuff originating from natural and semi-natural ecosystems), and ii.) inclination to follow the recommended food restriction by the authorities. The transfer to the general population is considerably lower (~a factor of 3) for the Chernobyl fallout than during the 1960's and 70's, which is partly explained by a higher awareness of the pathways of radiocaesium to man both by the public and by the regulating authorities, and by the time-pattern of the nuclear weapons fallout during the growth season in Sweden.

Total cancer incidence in relation to137Cs fallout in the most contaminated counties in Sweden after the Chernobyl nuclear power plant accident: a register-based study

“…However, the Swedish Defence Research Agency assessed the internal doses of persons living in different parts of Sweden using whole-body measurements of 134 Cs and 137 Cs 29. According to these measurements, yearly doses up to 10 mSv could have been received in the first years after the accident.…”

“…It is also possible that a higher deposition of 137 Cs on the ground might be associated with higher internal contamination according to the radio-ecological transfer factors given by Rääf et al29 for different subgroups in the Swedish population. Caesium is water soluble and is a chemical and metabolic analogue to potassium in living tissue; accordingly, it is absorbed by plants and mushrooms and concentrated in muscle tissue consumed as meat.…”

Cancer incidence in northern Sweden before and after the Chernobyl nuclear power plant accident

“…One way of calculating the internal dose could be using transfer factors based on whole body measurements of various population groups (Rääf et al 2006). This could be especially important for families of reindeer herders, farmers, hunters and people with habits of high consumption of wild mushroom, berries and fresh water fish retrieved near their homes.…”

Introduction of a method to calculate cumulative age- and gender-specific lifetime attributable risk (LAR) of cancer in populations after a large-scale nuclear power plant accident

“…Isotopic ratio 134 Cs/ 137 Cs at the time of initial fallout. A value of 0.56 was reported by [34] for the Chernobyl NPP fallout, and 1.1 for the Fukushima Daiichi NPP release [35]. The value for FR used here = 0.56.…”