Food ingestion doses from artificial radionuclides in Cumbrian diets, ten years post-Chernobyl

The ingestion of radioactively contaminated foodstuffs is a major pathway of radiation exposure in humans. A duplicate diet approach has been used to assess ingestion doses of the local population of west Cumbria in the United Kingdom. There has been historical interest in this population group, particularly those living close to the Sellafield nuclear installation, and the two major routes of ingestion exposure for them, namely the consumption of either local agricultural produce (the terrestrial pathway) or of locally derived sea foods (the marine pathway). We examine here the ingestion doses derived using radionuclide data from duplicate diet studies carried out during 1986, 1995 and 1996. The Chernobyl accident occurred during sample collection for the first survey; the latter surveys thus provide data to evaluate any changes in the ingestion dose up to 10 years after the accident. The contribution of Chernobyl fallout to the dose in 1986 was mainly due to radiocaesium (134Cs and 137Cs); in 1996, the 137Cs results are comparable to those obtained during the 1986 pre-Chernobyl survey, suggesting that radiocaesium activity concentrations in local foods from around west Cumbria have now decreased to pre-Chernobyl levels. The contributions of other artificial radionuclides (90Sr, 239+240Pu, 14C) analysed in the diet samples over the period are also assessed. Carbon-14, measured in the 1995 and 1996 surveys but not in 1986, is currently the most important contributor to the dose; in 1996, it accounted for at least 75% of the total ingestion dose from the radionuclides measured