Ionising radiation is produced by a beam of electrons striking a target, by cosmic radiation, radioactivity and nuclear reactions, which release energetic photons (gamma rays, x-rays) and/or particles. Ionizing radiation penetrates living organisms and alters cells, which then send signals to initiate various defensive responses.
Mass number of an atom
is the sum of neutrons and proton. It is given as a small number high up in front of the symbol of the element.
is the sum of protons of an atom. It is given as a small number down in front of the symbol of the element.
Every atom has a central, positively charged nucleus made of protons and neutrons. Nuclei are unaffected by chemical reactions. Protons and neutrons are collectively referred to as nucleons
Two atoms which have the same number of protons but different numbers of neutrons are called isotopes of each other. Isotopes have identical chemical properties and cannot be separated by chemical methods. The isotopes of hydrogen are:
Hydrogen ( 11H)
Deuterium ( 21D)
Tritium ( 31T)
The particles of the nucleus are held together by one of the four fundamental forces:
Strong interaction, also called nuclear force. This force is very strong.
Atomic warfare and atomic bomb tests in Nevada, Bikini and Soviet Union are responsible for high levels of strontium 90 fall out which caused high levels of strontium 90 in Brazil nuts growing in the rain forest of the Amazon region.
Nuclear energy is an important part of electrical power supply. It was considered to be clean energy.The disaster of Harrisburg and Chernobyl have demonstrated the danger of nuclear power stations. The fallout from Chernobyl made the killing and disposal of Norwegian reindeer.
Rising radioactivity of the Arctic region and its food chain is a product of uncontrolled nuclear handling.
The disposal of radioactive waste is unsolved problem for future generations. The salt mine of Gorleben in Germany is unsafe for disposal of nuclear waste.
Contamination of foods and feedstuffs by nuclear accidents
The accident of Chernobyl provided a lot of knowledge on contamination of the food chain. These information can now be applied in the actual Japan nuclear disaster. It is important to avoid milk of cattle which received grass and fodder of the contaminated region. As most of the radioactive particles end up in the ocean it is imperious to avoid sea foods of any kind. Do not drink tap water. More personal protection measures are described below.
The food chain safety will be compromised in the next decades by the situation in Fukushima. Primarily drinking water in Japan and Pacific fish and seafood will bear an increased load of radionuclides.
Japan prohibits the sell of shiitake-mushrooms
In the region of Fukushima shiitake-mushrooms (Lentinus edodes Sing) with high radiation were found. A total of 16 cities and towns are compromised. The ban was imposed on mushrooms cultivated outdoors. Mushrooms grown in greenhouses are safe and may be sold, according to Kyodo News. The local department of health reports a 1,55 times of the maximum permitted content of Iodine 131 and 1,78 times for Caesium in shiitake-mushrooms.
On April 1, shiitake mushrooms from the city Iwaki had a level of radioactive cesium of 890 becquerels per kilogram against the limit of 500 becquerels, reports Kyodo News.
Radionuclides in the food chain
The exposure may result from direct inhalation of contaminated air or ingestion of contaminated water, or from a less direct pathway, the ingestion of contaminated food products. The exposure may result from direct inhalation of contaminated air or ingestion of contaminated water, or from a less direct pathway, the ingestion of contaminated food products. The the contamination of the milk of the cow is a typical example to the incorporation of radionuclides in the food chain resulting of the ingestion of contaminated pasture, the so called the pasture-cow-milk exposure route.
Mushrooms from Bavaria, Germany, are still contaminated with radiating Caesium from the disaster of Chernobyl. German wild boars even after 25 years after Chernobil disaster are excluded from food market because they exceed the German limit on 600 Becquerel/Kg in meat. Wild boars like mushrooms which are highly contaminated by radionuclides.
The contamination of mushrooms with radionuclides depends on the type of mushroom and on the type of soil they grow on. The Cs-137 nuclides can highly be absorbed from forest soil where it is free available for plant roots. In agricultural areas the radionuclides are tightly bound to soil particles and their absorption is diminished. Sweet chestnuts and birch bolete are plant products with highest contamination.