Radioactive cesium in Swedish hunters

Exposure of German hunters and their family members to the radioactive nuclide 137Cs due to their eating habits

The radioactive nuclide ¹³⁷Cs that was released during the Chernobyl accident in 1986 is still present in the environment of wide parts of Middle Europe. It causes internal radiation exposure of people who incorporate this radionuclide when eating contaminated food, in particular boar meat and certain kinds of wild mushrooms. This study investigates the exposure of German hunters and their family members, which are supposed to consume these kinds of food more frequently than the general population. For this purpose, the body activity of ¹³⁷Cs was measured in 58 hunters and their family members mostly from Southern Germany and it was compared with body activities from 1729 measurements of 251 members of the general population. Significantly higher ¹³⁷Cs body activities were found in the hunters and their family members compared to the references after matching both groups for sociodemographic factors and the time of the measurement (factor of 2.4 between the geometric means, p-value ≪ 0.001). Within the hunters and their family members, an adjusted exponential regression showed significant associations of the activity and of mushroom picking (factor 2.6, 95% confidence interval 1.5-4.6) and of the frequency of having boar meat as part of the diet (factor 1.4 per meal per week, 95% confidence interval 1.1-1.8). No significant association was found for the ¹³⁷Cs surface contamination at the hunting grounds. Within families, mostly similar results were found in terms of activity concentrations. For the hunter with the highest measured activity (1050 Bq), an annual contribution to the effective dose of 35 μSv was calculated, showing that also in hunters and their family members ¹³⁷Cs is expected to cause only small contributions to the total effective dose from environmental exposure.

Increased cancer risk in male hunters compared to the general male population in Northern Sweden after the Chernobyl Nuclear Power Plant accident?

Male hunters in Swedish counties with high fallout of ¹³⁷Cs after the Chernobyl Nuclear Power Plant (NPP) accident have higher radiation exposure due to higher consumption of game compared with the general population.

Methods

Cancer incidence in Sweden was studied in 9 counties with different ¹³⁷Cs fallout after the Chernobyl NPP accident in 1986. In total, 9,267 cancer cases occurred in hunters and 138,909 cancer cases in non-hunters to 31 December 2015. Incidence rate ratios (IRR) with 95% confidence intervals (CI) were calculated using unexposed hunters, or non-hunters, as reference to study internal radiation exposure or hunter life style, respectively.

Results

Directly age standardized total cancer incidence showed an increasing trend in non-hunters. For hunters, the total cancer incidence was significantly lower up to 2001 when the total cancer incidence crossed over the weaker non-hunter trend and remained higher for the following 15 years. IRRs for total cancer in hunters versus non-hunters for each county did not show any clear exposure response pattern. IRRs for hunters versus non-hunters were higher regardless of rural/non-rural status with slightly higher risk estimates for the rural settings. The IRR for hunters was 1.06 (95% CI 1.04-1.08) 1986-2015, representing an excess of 531 cancer cases in hunters.

Conclusion

An increased total incidence of cancer was identified for male hunters compared with male non-hunters. No obvious association between cancer and ¹³⁷Cs from the Chernobyl NPP accident could be identified, although the exposure classification was too crude to exclude such an association.

Estimated lifetime effective dose to hunters and their families in the three most contaminated counties in Sweden after the Chernobyl nuclear power plant accident in 1986 - A pilot study

Hunters and their families were one of the most exposed subpopulations in Sweden after the Chernobyl nuclear power plant accident in 1986. In this pilot study we used existing registries and whole-body measurements to develop algorithms to calculate lifetime effective doses and collective doses to some hunters in Sweden. Ten hunters and their family members were randomly selected from each of the three most contaminated counties in Sweden (Västernorrland, Uppsala, Gävleborg) using the register for hunting weapons from the Police Authority in 1985. Hence, this design can be regarded as a closed cohort only including hunters and their family members living in these three counties at the time of the accident. Statistics Sweden matched these individuals (n = 85) with their dwelling coordinates onto the digital map produced by the Swedish Radiation Safety Authority after aerial measurements of ¹³⁷Cs (kBq m^-2). Internal effective doses were estimated using aggregated transfer factors from ground deposition to in-vivo body concentration for ¹³⁴Cs and ¹³⁷Cs in hunters (Bq kg^-1). External effective doses were also calculated on the dwelling coordinate for ¹³⁴Cs, ¹³⁷Cs and short-lived nuclides in these three counties. Annual effective doses for external and internal doses were then cumulated up to a life expectancy of 80 years for men and 84 years for women, respectively. The total lifetime effective doses to the members of the hunter families in this cohort were on average 8.3 mSv in Västernorrland, 4.7 mSv in Uppsala and 4.1 mSv in Gävleborg. The effective dose to men were about 40% higher than in women. In all counties the internal dose was about 75% of the total lifetime effective dose. The collective dose for all hunters with family members, in total about 44,000 individuals, in these three counties could be approximated at about 256 manSv. This study shows it is possible to use register data to develop algorithms for calculating lifetime effective dose commitments for hunters with relatively accuracy.