Øyvind Pedersen

Fungi : a major source of radiocesium contamination of grazing ruminants in Norway

Transfer of radiocesium from vegetation to milk was studied in dairy goats grazing heavily contaminated mountain pasture in southern Norway in the years following the Chernobyl accident. Radiocesium activity in milk and green vegetation remained stable throughout 1986 and 1987. In 1988, a sudden three- to fivefold increase in milk radioactivity occurred during the second half of the summer. Whole-body content of radioactivity in sheep and reindeer also increased rapidly. This coincided with an abundant growth of fungal fruit bodies with radiocesium levels up to 100 times higher than green vegetation. Fungal radiocesium was found to be highly available in a digestibility study with goats. Milk radioactivity levels in the field could be accounted for by consumption of as little as 20-100 g d-1 of fungal dry matter (DM). The importance of fungal fruit bodies in transferring radiocesium to ruminants was further substantiated by comparing meat activities in grazing ruminants in 1988 and 1989. Fungal fruit bodies were present in minor quantities in 1989, and radioactivity levels in sheep and reindeer in August-September were only 28-35% of those in 1988. This ability of fungi to mobilize radiocesium from natural soils and transfer the isotopes into the human food chain greatly enhances the vulnerability of food production in natural ecosystems to radiocesium pollution.

Hexacyanoferrates and bentonite as binders of radiocaesium for reindeer

The effects of varying doses of caesium binders (Bentonite and several forms of iron-hexacyanoferrates) on radiocaesium accumulation in red blood cells and on radiocaesium transfer to urine and faeces were studied in feeding experiments with reindeer calves. The caesium binders were added to a ration of lichen (containing 9.5 kBq of 134Cs+137Cs originating from the Chernobyl accident) and fed together with a pelleted reindeer feed (RF-71) for 42 days. A 50% reduction in red blood cell radiocaesium concentration was obtained with a daily dose of 1 mg/kg body weigth of ammoniumironhexacyanoferrate (AFCF) and with 500 mg/kg of bentonite. Three mg/kg of AFCF or 2 g/kg of bentonite reduced both urinary excretion and RBC concentrations with more than 80%. It is concluded that iron-hexacyanoferrates, as a result of their high caesium binding capacity, are particularly useful as caesium binders for free ranging ruminants like the reindeer. Hexacynoferrater og bentonitt som bindere av radiocesium i rein Abstract in Norwegian / Sammendrag: Effekten av bentonitt og ulike typer jernhexacyanoferrater (Berlinerblatt) pa akkumulering av radioaktivt cesium i rode blodlegemer og pa utskilling av radioaktivt cesium i urin ble undersokt i foringsforsok med reinkalver. Cesiumbinderne ble gitt daglig sammen med lav som inneholdt 9.5 kBq 134Cs+137Cs fra Tsjernobyl ulykken, og 1 kg reinfor (RF-71) i en periode pa 42 dager. En daglig dose pa 1 mg/kg kroppsvekt av ammoniumjernhexacyano-ferrat (AFCF) reduserte radiocesiuminnholdet i blodlegemer med 50%, mens en dose pa 500 mg/kg bentonitt var nodvendig for a oppna samme effekt. Tre mg/kg AFCF eller 2 g/kg/bentonitt var nodvendig for a oppna mer enn 80% reduksjon i radiocesium konsentrasjonen i blodlegemer og i radiocesium utskilling med urinen. Pa grunn av de sma daglige mengder som kreves er jern-hexacyanoferratene spesielt velegnete som cesiumbindere for beitedyr.

Transport and recycling of radiocesium in the alimentary tract of reindeer.

Transport of radiocesium between the body pools and the alimentary tract was studied in 7 reindeer calves. Comparisons were made between reindeer receiving the Cs- binder Prussian blue (Ammon-ium-ironhexacyanoferrate) and untreated animals. The calves were fed lichens contaminated with 134Cs + 137Cs from the Chernobyl accident (about 10 kBq/day) for 4 weeks. Absorption and secretion of radiocesium, Na and K in the alimentary tract were calculated using 51Cr-EDTA as a reference substance. Thirteen sections of the alimentary tract were sampled and analysed for radionuclides and chemical composition. In 4 animals, feeding with contaminated lichens continued until they were slaughtered, whereas in the 3 others the lichen feeding terminated 4 days before slaughter. The activity concentration of Cs nuclides increased 5-17 - fold from duodenum to the distal colon, whereas the concentration of Na decreased and K remained almost constant. Radiocesium, Na and K were secreted into the rumen, the omasum and the abomasum, whereas Na and K also were secreted into the proximal small intestine. Prussian blue had no effect on Na and K recycling, but the flow of radiocesium from the abomasum to the anus and the fecal excretion increased markedly. In the 3 animals where feeding with contaminated lichens was disconutinued 4 days before slaughter, endogenous Cs was continuously recycled between the body pools and the alimentary tract. The net exchange of radiocesium between body pools and the alimentary tract was more than 4 times the amount ingested when lichens were fed. It is concluded that radiocesium is rapidly recycled between the alimentary tract and the other body pools. Cs-binders like ammonium-ironhexacyanoferrate may bind both endogenous Cs and Cs from feed.

Radiostrontium, radiocesium and stable mineral composition of bones of domestic reindeer from Vågå, Norway

Radiostrontium, radiocesium and macromineral concentrations were measured in metatarsal or metacarpal bones from 78 reindeer (59 calves and 19 adults) in the Vaga reindeer herding district in Southern Norway. Samples were collected in the period August 1988 to May 1989. Radiocesium concentrations increased from August through the winter. Radiostrontium varied slightly around an average value 1810 Bq/kg DM. Mg concentrations decreased through the winter, the concentrations of other minerals and bone density showed only small variations. No signs of mineral deficiencies were observed. It is concluded that radiostrontium mainly originated from the Chernobyl nuclear accident. Radiostrontium, radiocesium og stabile mineraler in reinknokler fra Vaga, Norge Abstract in Norwegian / Sammendrag: Innhold av radiostrontium, radiocesium og makromineraler ble malt i reinsdyrknokler (metatarsus og metacarpus) innsamlet fra 78 dyr (59 kalver og 19 voksne) tilhorende Vaga tamreinlag. Provene ble samlet i perioden august 1988 til mai 1989. Innholdet av radiocesium okte fra august og gjennom vinteren, mens innholdet av radiostrontium var temmelig konstant (1810 Bq/ kg torrstoff). Magnesium innholdet avtok gjennom vinteren, mens innholdet av andre mineraler samt knoklenes tetthet varierte lite. Det ble ikke observert noen tegn pa mineralmangel. Mesteparten av det radioaktive strontium kom fra atomkraftulykken i Tsjernobyl.

Different approaches for estimating the deposition of radiocaesium on mountain pasture in Southern Norway

Different approaches to the estimation of radiocaesium deposition on different types of indigenous mountain pastures have been examined. In situ gamma spectrometric measurements performed using a portable multi-channel analyser (3 x 3 in Nal detector) with the detector placed on the ground, on a tripod at a height of 100 cm above the ground or fastened to a rucksack frame 90 cm above the ground were compared with conventional soil sampling. Field gamma-ray measurements in connection with soil sampling appear to be a promising tool for estimates of deposition on mineral soils in areas with different topography and vegetation.

Equipment for placing a sustained release bolus in the rumen of reindeer

A pair of pliers were developed to place sustained release boli with a diameter of 18-20 mm and a length of 50-60 mm safely into the rumen of reindeer. The pliers are connected to a flexible, plastic coated steel tube terminating in a bronze headpiece. Inside this tube a polyfilament, stainless steel wire connects the pliers to an attachment screw in the headpiece. Before treatment the bolus is screwed on to this screw. After the bolus has been guided through the pharynx and oesophagus into the rumen, it is released by squeezing the pair of pliers which then retracts the attachment screw and allows the bolus to drop off. Spring loading of the attachment screw ensures retraction of the screw into the headpiece if the bolus is lost during the operation. The equipment has been used for treatment of more than 1000 reindeer. Utstyr for nedforing av tabletter i vomma pa rein. Abstract in Norwegian / Sammendrag: Et nedleggingsutstyr for innforing av vomtabletter i vomma pa rein blir beskrevet. Vomtablettene har en diameter pa 18-20 mm og en lengde pa 50-60 mm. Utstyret bestar av en tang som via en boyelig, plastbelagt spiralwire er forbundet med et hodestykke i bronse. En polyfilament stalwire gar inne i spiralwiren fra tangen til hodestykket hvor den ender i en festeskrue. For behandling skrues festeskruen inn i et hull i bakflaten av vomtabletten. Etter nedforing i vomma frigjores tabletten ved at festeskruen med kraft fra tanga trekkes ut av tabletten. Fjaerbelastning av festeskruen sikrer at skruen trekkes inn og beskyttes i hodestykket dersom tabletten mistes under behandling av urolige dyr. Det er behandlet ca 1000 rein med nedleggingsutstyret. En behandling med to tabletter tar 2-5 min. pr. dyr inkludert nedlegging og fiksering av dyret.

Effect of sodium and potassium supplementation on accumulation and excretion of radiocaesium in reindeer

We tested the effect of sodium and potassium supplementation on radiocaesium excretion and accumulation in reindeer eating lichens (winter diet). Nine reindeer were divided into 3 groups of 3 animals. One group was daily given 0.35 M KC1, one was given 0.35 M NaCl (both dissolved in 1 1 water), and one group was kept as a control with no mineral supplement. The animals were contaminated with 137Cs from radioactive pasture. During 3 weeks before the experiment the 137Cs concentrations were maintained by daily supplementation of 157Cs sprayed on lichens. From the start of the experimental period the animals received identical large daily doses of I34CsCl. Animals which were given KCl supplementation showed a lower accumulation of 134Cs in red blood cells (RBC) and a faster decrease of 137Cs in RBC than control animals. Sodiumchloride supplementation had no clear effects on radiocaesium concentrations in RBC. Mineral supplements did not affect excretion of radiocaesium via faeces. Supplement of KCl or NaCl increased urine production and the amount of radiocaesium excreted via the urine. It is concluded that increased K intake decreases the radiocaesium concentration in the animals more than is explained by increased urine production alone. This supports the theory that increased K concentration in the diet may contribute to a fast elimination of radiocaesium in reindeer during spring.

Effect of Prussian blue (ammonium-iron-hexacyanoferrate) in reducing the accumulation of radiocesium in reindeer

Laboratory experiments. Prussian blue (Giesesalt) in closes of 50, 150, 300, 750 and 1500 mg was added to a daily ration of 1 kg reindeer feed (RF-71) and 0.25 kg lichen dry matter providing 8-10 KBq/d. Two reindeer calves were used per treatment, and the results compared to radiocesium accumulation in four control calves (no Prussian blue). Red blood cell activity increased in control animals from background levels to between 400 and 500 Bq/L and were still increasing after six weeks of observation. N o accumulation of radiocesium could be detected in the calves treated with 300-1500 mg/d of Prussian blue. A moderate increase was observed at the lowest doses. Thus daily doses as low as 150 mg of the Prussian blue preparation practically prevented the absorption of radiocesium. Field trials. Sodium chloride stones with 2.5% Prussian blue were provided to a herd with a body load of about 10 KBq/kg meat. After exposure to the stones for 24 d the average radioactivity in adult females was reduced from 10.5 to 6.6 KBq/kg (37%). Large differences in the intake of salt were evidenced by individual reductions in blood radioactivity varying from 0 to 70%. Salt eaters were easily distinguished by blue muzzles. Rangifer, Special Issue No. 3, 1990: 43 Rangifer, Special Issue No. 3, 1990. 43

Effects of administration of potassium- and sodiumchlorides on faecal excretions and salivary and alimentary concentrations of, Na, K, 134Cs, Ca, Mg and P in reindeer fed a lichen diet

A comparison of the effects of administration of 350 mmol d-1 of KC1 or NaCl on faecal excretions, salivary concentrations and concentrations and pools of Na, K, 134Cs, Ca, Mg, P, and water in the alimentary tract of reindeer was carried out using three groups of three 10 months old reindeer fed a lichen diet. One group was used as a control group with no mineral supplementation. The level of K supplementation mimicked K intakes from summer pastures. NaCl was given at a rate which would mimic intake from salt licks by domestic ruminants of similar body size. Treatment with KC1 increased the salivary and alimentary concentrations and the alimentary pool sizes of K and faecal excretion of K increased. A decrease in l34Cs concentrations in all parts of the gastrointestinal tract indicated greater absorption of 134Cs during the KC1 treatment than in NaCl treated and control animals. Increased intake of Na or K had no significant effect on the digestibility of the lichen diet, but urine production increased. Little effects on pools or concentrations of Ca, Mg and P were observed. NaCl treatment increased urinary and faecal excretion of Na, but did not affect the metabolism of any of the other studied minerals.

Effects of ammoniumiron-hexacyanoferrate on the accumulation of radiocesium in reindeer

It is concluded that a sustained release bolus for administration of a cesium binder of the ironhexa-cyanoferrate type provides a promising method for reduction of radiocesium uptake from contaminated pastures. Included is also a discussion after Hoves lecture.