Cancer Incidence Related to Absorbed Colon Dose in Male Hunters and Non-Hunters in Northern Sweden after the Chernobyl Nuclear Power Plant Accident – a Comparison within Two Separate Cohorts

IntroductionMale hunters have slightly higher total cancer incidence versus male non-hunters in Sweden after the Chernobyl Nuclear Power Plant (NPP) accident. This study analyses the relationship between cancer incidence and absorbed colon dose within these two cohorts separately.Material and methodsIn two closed cohorts of non-hunters (n=785,514) and hunters (n=40,874) individual absorbed colon dose was calculated 1986-2015. Allowing for a 5-year latency period, the age-adjusted Incidence Rate Ratios (adj IRR) per milliGray (mGy) with 95% Confidence Intervals (CI) was analyzed using Poisson regression. A total of 8,964 cancer cases occurred in the hunter and 118,145 cancer cases in the non-hunter cohort from 1 January 1991 to 31 December 2015. Cancer was classified in: 1) Organ-specific (stomach, colon, liver, lung, prostate, urinary bladder, thyroid and leukaemia), 2) Other and 3) Not previously associated to ionizing radiation.ResultsThe mean colon dose was 2.39 mGy (95 th percentile 8.85 mGy) in hunters and 1.69 mGy (95 th percentile 4.80 mGy) in non-hunters, respectively. Increased adj IRR was seen in Total cancer in non-hunters explained by Organ-specific cancer, but such increase was not seen in hunters. In non-hunters the Organ-specific adj IRR was 1.023 (95% CI 1.018-1.027), an increase not seen in hunters. Within Organ-specific cancer increased adj IRR was only seen for prostate, colon and urinary bladder cancer in non-hunters. Other radiation associated cancer sites did not show increased adj IRR either in hunters or non-hunters. In cancer sites Not previously associated with ionizing radiation there was no identified cancer risk in either cohort.ConclusionsSome cancer sites previously associated with ionizing radiation showed a positive correlation with the absorbed colon dose after the Chernobyl NPP accident in non-hunters, but not in hunters. The increased cancer risk in hunters versus non-hunters did not seem being related to the Chernobyl fallout.