Initial information since the releases of radioactive materials from the Fukushima Daiichi nuclear power plant, in Japan, shows that some animal food products are contaminated with 131I (mostly milk) and, to a lesser extent with 134Cs and 137Cs. Current knowledge on the transfer of these radioisotopes to animal products and available relevant countermeasures and management options to reduce radiation doses to humans are summarized. Much of this knowledge was obtained during the years of global fallout from atmospheric nuclear weapons tests and the response to the Chernobyl accident, in Ukraine in 1986.

An overview of the transfer of radionuclides to farm animals and potential countermeasures of relevance to Fukushima releases.

AFCF and clinoptilolite use in reduction of (137)Cs deposition in several days' contaminated broiler chicks.

The ECOSYS foodchain model is built into the European standard decision support systems ARGOS and RODOS, which are integrated in the preparedness for radiological events in the Nordic countries. However, a review has revealed that a number of parameters in ECOSYS do not reflect the current state-of-the-art knowledge, and do not adequately represent Nordic conditions. Improved and country/region specific data is required for ECOSYS to give trustworthy results. It is the aim of the PardNor activity to collect new data, and thus enable reliable use of ECOSYS for scenarios involving contamination of Nordic food production areas. In the reported work period of the PardNor activity, examinations have been made of the availability in each of the Nordic countries of soil characterisation data that could be used as a basis for a refined and location-specific approach for estimation of soil-to-plant transfer of contaminants. Large national gridded soil type databases were found to be available for most of the Nordic countries. In addition, for many of these countries, also a number of more detailed soil parameter values, such as local concentrations of various exchangeable ions, cation exchange capacity and soil pH are available on national grids. The feasibility of implementing each of two detailed crop uptake models in ECOSYS The CoupModel and the ‘Absalom’ model was investigated. Both models were found to have serious constraints in this context, and it was therefore recommended to apply a simpler soil classification. To this end, a review was made of state-of-theart transfer factor data for different soil types, and for the Faeroe Islands, where gridded information is not available, a different approach was described. A preliminary study was also included, on using the Radiocaesium Interception Potential (RIP) as a transfer parameter, utilising the very low RIP values caused by the geological conditions in Iceland. Parameters describing the processes of incorporation and excretion by farm animals of ingested contaminants were also examined, and new datasets for transfer parameters and biological half-lives were derived.

PardNor – PARameters for ingestion Dose models for NORdic areas - Status report for the NKS-B activity 2010

The effect of RADEKONT (a natural clinoptilolite modified by hexacyanoferrate) on 137Cs uptake into meat was tested in experiments with broiler chickens. Three experiments determined the influence of RADEKONT on radiocaesium transfer after single or repeated applications of artificially contaminated feed mixture and one experiment investigated the effect of RADEKONT when feeding a mixture containing wheat contaminated by the Chernobyl fallout. Independent of the effect of RADEKONT, the uptake of radiocaesium was faster in leg meat than in breast meat. Reduction factors (137Cs transfer without the RADEKONT additive compared with those observed after supplementation of the additive into the feed mixture) of 1.1–1.3 and 1.2–2.3, respectively, were achieved after single and repeated administrations of artificially contaminated feed. No significant differences in reduction between breast and leg meat were observed. RADEKONT was more effective when the chickens were fed with Chernobyl-contaminated wheat (reduction factors of up to 3.7) than an artificial 137Cs source. RADEKONT as a supplement during the decontamination period decreased the biological half-life of 137Cs to less than 1 day. The timing of the application of RADEKONT might be important in determining its effectiveness, especially in young, rapidly growing chickens.

Reduction of radiocaesium transfer to broiler chicken meat by a clinoptilolite modified with hexacyanoferrate

The aim of the present study was to investigate distribution of 137Cs in leg and breast meat of broilers and pheasants following single alimentary contamination and administration of two protectors (AFCF and clinoptilolite). The birds were administered a single dose of 137CsCl, with an activity of 750 Bq. Protectors were given via gastric tube or mixed in the forage pellets. AFCF given via gastric tube decreased the 137Cs concentration by a factor of 7.8 in broilers leg meat and 7.4 in broilers breast meat. When AFCF was mixed in pellets, the 137Cs concentration was 19.5 times lower in broilers leg meat and 22.1 times lower in broilers breast meat, than in the control group. In pheasants, AFCF administered via gastric tube decreased the 137Cs concentration by a factor of 12.4 in leg meat and by a factor of 13.7 in breast meat, respectively. In group 4, where pheasants were administered AFCF mixed in pellets, the 137Cs concentration was 3.7 times lower in leg and breast meat, than in the control group. For comparison, clinoptilolite administered via gastric tube decreased the 137Cs concentration 1.8 times in broilers leg meat and 2.0 times in breast meat, compared to the control group. In pheasants, 137Cs concentration was 2.9 times lower in leg meat and 2.6 times lower in breast meat. Clinoptilolite mixed in the feed had relatively low efficiency of protection in broilers (137Cs concentration was 1.4 times lower in leg meat and 1.6 lower in breast meat). A similar trend was observed in pheasants (137Cs concentration was 1.6 lower in leg and breast meat).

Comparative study of (137)Cs distribution in broilers and pheasants and possibilities for protection.

The distribution and biological half-life of radiocaesium (137Cs) in broiler chickens after three oral applications (in course of 1 day at the age of 14 days) of artificially contaminated feed mixture were studied. There was a rapid uptake of the orally administered 137Cs (within a few hours) and also a rapid loss of 137Cs which varied in the different organs (the initial biological half-life was: liver 0.6 day, intestine 0.6 day, breast meat 2 days, leg meat 1.2 days). More than one-half of the total administered 137Cs activity (55%) was excreted from the body within the 1st day after dosage, and after 14 days more than 90% had been excreted. The highest accumulation of 137Cs occurred in meat (50%–90%), and the proportion of total activity in breast and leg meat varied during decontamination. The transfer of radiocaesium from feed into the chicken body (measured as ratios of the 137Cs activity concentrations in the organ to the 137Cs activity concentration in the applied dose) 1 day after application was: 0.0220, 0.0294, 0.0216 and 0.0195 for breast meat, leg meat, intestine and liver, respectively. Significant differences between the values were demonstrated (P<0.05) except between those of breast meat and intestine. For the first 3 days there was a higher proportion of 137Cs activity in leg meat, whereas from the 4th day a greater part of total activity was found in breast meat. The latter results were confirmed in a subsequent study. Data from this study suggest that if broiler chickens are contaminated by radiocaesium to a level of 5 kBq/chicken in the course of 1 day at the age of 14 days, then immediate feeding with uncontaminated feed mixture for 18 days should be effective in decontaminating the chicken's meat below the intervention levels for radiocaesium in animal products, i.e. below 1000 Bq ⋅ kg–1.

Vladimír Borkovec

Papers

Dynamics and distribution of radiocaesium in broiler chicken.