**5.7. Seafood and fish**

#### *5.7.1. Fish*

mainly from eastern and southern Switzerland. The contamination levels in the meat were higher in regions with higher depositions of fallout. In southern Switzerland, the radiocaesium activity concentrations varied from 40 to 4400 Bq/kg. The highest value was found in a goat. In contrast to this, in eastern Switzerland, values were from 40 to 1300 Bq/kg. In the other parts of Switzerland, even lower values were found. Almost 2000 samples from imported meat were analysed. Here, 251 samples had to be rejected due to values more than 600 Bq/kg. During the year 1986, a reduction of the contamination level was observed, with the exception of southern Switzerland (cantons of Ticino and Grison). The biological half-life for radiocaesium was calculated to be approximately 50 days for sheep and goat and approximately 30 days for game.

Game became of interest when high radioactive contaminations of reindeer were reported in Norway and Sweden. The northern European countries were more highly contaminated with radioactive fallout from Chernobyl than other European countries. Wild berries, mushrooms, and lichens are the main food of reindeers. These were seriously contaminated with this fallout. Thousands of animals had to be burnt because of a violation of radiocaesium values that were too high. The survey of game in Switzerland began in autumn 1986. We analysed meat from five roe deer and deer with γ-ray spectrometry. The activities were not high. Nevertheless, in 1987, the contamination of the game meat showed higher values up to 7 kBq/kg radiocaesium. From 1986 on, game was investigated yearly. In 1990, four objections had to be executed according to our measurements. It seemed that chamois were the most contaminated game in Switzerland. After 1995, the monitoring programme was reduced. The detected radioactivity

Wild boars are an exception. The southern parts of Switzerland, such as in Bavaria (Germany), are more contaminated landscapes. Here, the contamination of wild boar remains a problem up to today. Wild boars search for their food on the ground. Elaphomyces, a truffle species, grow underground and are able to enrich radiocaesium from soil. It is estimated that these fungi can be up to 20% to 30% of the food of wild boars. In 2012, in southern Bavaria and the Bavarian Wood, the contamination levels were up to 9.8 kBq/kg wild boar and up to 430 Bq/kg in roe deer [50]. In Switzerland, the State of Ticino, in collaboration with the Federal Office of Public Health, investigated wild boars in 2013 and 2014. In 2013, 28 wild boars of a total of 470 animals violated the limit value of 1250 Bq/kg. In 2014, they found 13 such contaminated animals. These animals had to be confiscated [17]. In contrast, in the State of Zurich, the State Laboratory Zurich found no violations when they analysed 80 wild boars. The mean activity was low with 28 Bq/kg radiocaesium [51]. In 2014, the Umweltinstitut München reported from their monitoring programmes for wild-grown vegetables and game. More than 2000 samples showed contamination levels over the limit value of 600 Bq/kg, and 141 samples showed radiocaesium activities of more than 10,000 Bq/kg. Ten samples contained more than 16,000 Bq/kg. The maximum value was 27,800 Bq/kg [52]. Therefore, the serious

Pigs showed a half-life of 90 days [49].

was under the tolerance limit of 600 Bq/kg.

contamination rests a problem in Bavaria.

**5.6. Game**

144 Radiation Effects in Materials

In Switzerland, we analysed fish from the Rhine River at Basel for radioactive contamination in 1986. Fifteen species caught by local fishermen contained 22 to 707 Bq/kg radiocaesium. These activities were not alarming, as fish are not an important part of the daily food con‐ sumption in Switzerland. Again, the most affected region was the southern part of Switzerland. The mean activity of 70 fish species caught in the lake of Lugano was 1.09±0.6 kBq/kg radio‐ caesium with a maximum value of more than 4.4 kBq/kg, approximately five times higher than in fish from other lakes of Switzerland. This lake has no major confluences and effluents such as the lake of Maggiore where the contamination level of fish was quite lower [49, 55]. After 1987, the contamination with radiocaesium from the Chernobyl fallout was reduced and reached a level of approximately 0.2 Bq/kg for 137Cs [56].

The accidents at the Fukushima-Daiji NPPs gave us cause to investigate fish importation from the Pacific Ocean. Approximately 90% of the released fallout reached the sea (4–90 PBq 137Cs). Radiocaesium levels in fish reached 200 kBq/kg. In 2011, the Japanese Government banned fishing in the coastal waters near Fukushima NPP and the fishing of fish species in some prefectures, which are severely contaminated. Local, private associations of fishermen voluntarily imposed a limit value for radiocaesium of 50 Bq/kg [57]. Also in territorial waters, such as lakes, ponds, and rivers, fish accumulated radioactivity from fallout. Here, radioac‐ tivity levels reached approximately 10 kBq/kg fish. In 2012, an intensified monitoring pro‐ gramme of Pacific blue tunas off the Californian coast showed a slight contamination of the fish (0.7±0.2 Bq/kg 134Cs and 2.0±0.5 Bq/kg 137Cs). The presence of the short-lived 134Cs proves the contamination from the Fukushima fallout [58–61]. A received dose of 1 mSv/year was estimated from the consumption of 50 kg fish caught within a zone 3 km away from the Fukushima NPP. Our own investigations of imported fish from the Pacific show a relatively low contamination level below 1 Bq/kg radiocaesium, with a mean value of approximately 0.3 Bq/kg. Some fish samples also contained the short-lived caesium-nuclide 134Cs [62]. Only 14% of the total dose of the consumption of fish and sea food originates from artificial radionuclides, and 86% is from natural radionuclides, such as polonium (210Po).
