Subsections

Radioactivity and food

Radioactivity is the property of atomic nucleus to change spontaneously to another nucleus by itself, without the influence from outside, releasing energy in form of particles and/or electromagnetic rays.
The parent nucleus is called the emitting nucleus which changes its atomic number and becomes the nucleus of a different element being called daughter nucleus or decay product.

Ionizing radiation:

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.

Atomic number:

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


Isotopes:

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 ( $^{^{1}}_{_{1}}H$)
Deuterium ( $^{^{2}}_{_{1}}D$)
Tritium ( $^{^{3}}_{_{1}}T$)
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.
Electromagnetic force.
Weak interaction.
Gravitational force.
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 trash is unsolved problem for future generations. The salt mine of Gorleben in Germany is unsafe for disposal of nuclear waste.


History of radioactivity

1895 Roentgen rays (X rays) were discovered by Röntgen.
1896 Radioactivity was discovered by H.Becquerel working with uranium at the Ecole Polytechnique in Paris.
1898 Discovery of radioactivity of thorium by C.G. Schmidt at the same time with Madame Marya Curie. In the same year Madame Curie isolated from pitchblende (uraninite) polonium and radium.
1899 Discovery of actinium by Debierne, collaborator of Madame Curie. Actinium is a very rare element.
1934 The first artificial atomic nucleus was created by J. and Irène Joliot.
This discovery opened the way to further studies in modern particle accelerators.
1963 FDA approves the use of irradiation in food to control insects in wheat and wheat flour. Another application of irradiation which was approved by the FDA was the inhibition of sprouting of potatoes.
1980 The Food and Agriculture Organization (FAO), the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO)concluded that the irradiation of food up to a maximum dose of 10 kilo Grays is considered to be safe .
1983 FDA approves the irradiation of spices and seasonings.
1985 FDA approves irradiation of pork to control trichina.
1990 FDA approves the irradiation of packaged fresh or frozen unheated poultry.
1992 FDA based on a review data and information concluded that irradiated food is safe and nutritionally adequate. 1997 FDA approves the irradiation of red meats.

Different types of rays

Electron beams


X rays:

Radiation was used in many ways as X rays in medical use and industrial purposes.

Radiation of uranium:

Radiation of uranium includes alfa- beta- and gama rays.

Alfa rays

are positive charged particles of helium nuclei(two protons and two neutrons). Alfa rays are heavy and are stopped by a piece of paper. They are therefore not interesting for technological irradiation of food. Alpha particles are the most energetic form of radiation produced by radioactive decay. As they are charged and move relatively slowly ( 6% of the velocity of light], they produce high ionization, loosing their energy over a short distance producing considerably ionization.
An alfa decay of a nucleus takes place when the nucleus loses four nucleons, two of them are protons. Uranium-238 decays by alfa-emission to thorium 234.
The mass number decreases by 4.
The atomic number decreases by 2.

Beta rays:

are negative charged very fast electrons with near light velocity.Beta particles are emitted by nuclei which have to many neutrons to be stable. One neutron changes then into a proton and an electron which is emitted as beta particle.
The mass number does not change.
The atomic number increases by 1.
Beta rays are used for irradiation of food because of their high penetration.
The radioactivity of carbon can be use to date archaeological samples.
As an example suppose that an archaeological sample has an activity of 7,5 disintegrations per minute, and that an equal mass of carbon from a living plant has an activity on 15 disintegrations per minute. The activity of the sample is one half that of the present day level and therefore its age is equal to the half-life of C 14. The sample is therefore 5.730 years old.

Gama rays:

are electromagnetic waves which are very short and bear high energy. In comparison with alfa and beta particles they produce very little ionization and are very penetrating


Radiation of cobalt-60:

Irradiation of food is practiced most frequently with cobalt-60 as radiation source with emission of gama and beta.
The technology of the future will probably be the irradiation with X-rays which penetrate the food more effectively than gama rays of cobalt 60 does. X-rays can be switched off when the rays are not needed.
Cancer cells can be destroyed by gama-radiation from cobalt 60.


Irradiation of food

Irradiation of food can prolong shelf-life, reduce spoilage, reduce the menace of pathogens, delay ripening of fruits and vegetables avoiding the sprouting of potatoes [1626].
The acceptance of irradiated food is very low because safe foods can be produced without radiation. The problems of Salmonella in poultry must be handled by monitoring the poultry feed, by hygienic measures of poultry stables and last but not least hygienic measures in kitchen.
It is not known if radiolytic products and free radicals which are created by irradiation are harmless or toxic and essential nutrients such as vitamin E are reduced by radiation. Foods with high fat content such as oily fish and some dairy products , develop off-odors even with low dosis. Other technologies of food processing may cause more damage to the food as radiation does. The problem of the disposal of useless cobalt-60 units still unsolved. Germany has decided to exit atomic energy programs in order to reduce radiation garbage.

Irradiation detection tests

Lipids from not cooked foods under ionising rays form a cyclic compound 2-alkyl-cyclobutone. Hydrocarbons of irradiated lipid-rich foods can also be detected.
Damage of the DNA caused by radiation may also be detected on unheated foods.
Cell membrane damage may cause changes of the physical properties of irradiated foods such as: electrical impedance, viscosity, electrical potential, electron spin resonance (ESR) and thermal and nearinfraread analysis as well as thermoluminescence. Minerals trapp in their crystals free radicals originated by irradiation. These crystals are responsible for theroluminescence which can be used for the detection of irradiation of vegetables, fruits, grains and spices because all contain minerals. The same phenomena takes place in bone bearing foods where ESR may be used to detect irradiated food such as chicken with bones.
Boneless chicken, liquid egg nd certain fruits are analysed by mass spectrometric detection of 2-alkylcyclobutanones after gaschromatgraphic separation.

Low body exposure to radiation

Low fractionated body exposure to radiation can activate immunological resistance. This is being used in tumor therapy. That is why short rest in certain radioactive caves are being used in the treatment of some sanitariums and mineral water with low radioactivity is being sold in Brazil. High dosis of radioactivity are responsible for a decrease of immunity because of the reduction of lymphocytes causing an increase of infections and cancer risk [1629].

Natural radioactive exposure

Radon:

Radon and its decay products which are present trapped air in rooms can be reduced with fresh air[1628].
Radon endangers lung.

Air pollution from coal power plant:

All minerals have a low natural radioactivity, so does coal. As it is being burned the radioactive part concentrates in the ash and through exhaust gases it comes to the atmosphere and causes fallout of isotopes of uranium, polonium and lead.

Air travel:

Cosmic radiation is very high. The atmosphere is a natural shiel against this radiation. Air traffic at high altitude is exposed to increased radiation because of a thin atmosphere leading to 5 microSievert/hour (0,5 millirem/hour). This is very important for aircraft crews who are due to their profession exposed to this radiation.


Phosphate fertilizer:

Phosphate fertilizer are being utilized in great amount in modern agriculture. As phosphate fertilizer contain radioactive parts increase the natural exposure of people engaged in storage an handling including an increase of radiation of fertilized plants. This leads to an exposure of 40 millirem/year[1630].


Mineral water:

Drinking 60 liters of mineral water in a year leads to 300 millirem/year.


Cigarette smoke:

Tobacco has lead-210 and Polonium 210 as natural isotopes. Smoking during 25 years leads to an exposure of 20 000 millirem.
Life has been always submitted to natural radiation. A low level of radioactivity can cause small damage to DNA. The body can repair this by itself. It triggers th immune system. As the radioactive contamination caused by civilization rises, it becomes dangerous because of deposition in bones and organs concentrates radioactive material. The only way out of this dilemma is to reduce growing industrialization, reduce traffic, is to return to small ecological limited populations and to be satisfied with a normal life avoiding the destruction of earth.

Radiation sensitivity of Women and unborn child

[1634]
According to Prof. Dr. Wolfgang-Ulrich Müller, radiation sensitivity of the unborn child is particularly high, while radiation sensitivity of women appears to be twice as high as that of men.

Furthermore, radiation sensitivity of the eye lens is higher than previously assumed. Research in this field must be continued and intensified, and lowering the limit value for the eye lens must be investigated as a matter of urgency.

Half-life period of radioactive material

The half-life period is the time in which half of a certain amount of radioactive material will decay.
An element with 1600 years as half-life period has after 1600 years half of its material still active. After another 1600 years half of this amount is still active, one-fourth of the initial amount from 3200 years ago. It takes another 1600 to reduce it to one-eighth of the initial amount of 4800 years ago.
Some examples demonstrate the necessity to handle radioactivity with great care as radioactive garbage will remain as burden for thousands of generations to come:

Element Half-life
   
Uranium-238 ( $^{^{238}}_{_{92}}U$) 4 510 000 000 years
Uranium-235 ( $^{^{235}}_{_{92}}U$) 704 000 000 years
Uranium-234 ( $^{^{234}}_{_{92}}U$) 247 000 years
Radium-226 ( $^{^{226}}_{_{88}}Ra$) 1 600 years
Radon-222 ( $^{^{222}}_{_{86}}Rn$) 3,82 days
Polonium-214 ( $^{^{214}}_{_{84}}Po$) 1.6 X $10^{-4}$ seconds
Polonium-218 ( $^{^{218}}_{_{84}}Po$) 3.05 minutes


Radiation hazards

The extend of the harm caused to cells by radiation depends on the nature of the rays, the part of the body exposed to radiation and the dose received.
Nature of rays: Alfa- particles are absorbed in the dead surface layers of the skin and are therefore not dangerous. If the source however is taken into the body through food, water or dust. Alfa rays can cause great damage.

Radiation dose:

Radiation doses the energy absorbed by a unit of mass. It is measured in gray (GY) units ( 1 Joule is absorbed by 1 Kg mass). 1 GY = 1 Jkg old writings used 1 Gy = 100 rad
Unified atomic mass unit ( u )
1 u = 1.660 X $10^{-27}$kg
1 u = 931 MeV


Relative biological effectiveness ( RBE-Values)

In order to take account of the different biological effects of the different radiations it is useful to define the effective dose as :
Effective dose = Radiation dose X RBE
The RBE values are given below:

Radiation RBE
   
X rays 1
Beta, gama and X 1
High Speed neutrons 10
Alpha rays 20

Measuring radiation dosage [1633]

There is a relationship between radiation dose and its effect on the body. Radiation dosing can be thought of as an amount of energy absorbed by the body.

The rad:

The rad is a unit of absorbed radiaton dose defined in terms of the energy actually deposited in the tissue. One rad is an absorbed dose of 0.01 joules of energy per kilogram of tissue.

RBE:

To accurately assess the risk of radiation, the absorbed dose energy in rad is multiplied by the relative biological effectiveness (RBE) of the radiation to get the biological dose equivalent in rems. The RBE is a "quality factor," often denoted by the letter Q, which assesses the damage to tissue caused by a particular type and energy of radiation.

For alpha particles, Q may be as high as 20, so that one rad of alpha radiation is equivalent to 20 rem. The Q of neutron radiation depends on their energy. However, for beta particles, x-rays, and gamma rays, Q is taken as one, so that the rad and rem are equivalent for those radiation sources

The jungle of units

The effective dose is labeled as Sievert (Sv)
An old unit for effective dose had been the rem (röntgen equivalent man)
1 rem = 1 rad times RBE
1 Millirem ( mrem ) = 0.001 Sievert
1 Sv = 100 rem
The unit of the activity of radioactive material is Becquerel (Bq): 1 Bq = 1 decay/second.
The old unit of activity replaced by Bq, is Curie (Ci):
1 Ci = 3,7 X $10^{10}$ decays/second = 3,7 X $10^{10}$ Bq.


Energy dose:

The rays of radiation have an interaction with the mass of the body which is being irradiated. This is called energy dose. The unit is Gray (Gy) , which means that 1 joule is absorbed by 1 kg of body.
1 Gray (Gy) = 1 J/Kg
The old unit of energy dose was Rad (Radiation absorbed dose)Radiation absorbed dose 1 Gray (Gy) = 100 Rad


The mass-energy relation of Einstein

According to the theory of relativity mass is equivalent to energy in accordance to:
E = mc$^{2}$ where c is the speed of light (3 X $10^{8}$ m )$s^{-1}$

Mass-energy during an atomic fission:

When 1 kg of uranium-235 undergoes fission the energy released is 80 000 000 000 000 J corresponding to a decrease in mass of 0,9 gram. This is a significant loss of mass and can be measured.

Mass-energy during a chemical reaction:

Chemical reactions release relatively small amounts of energy and the decrease in mass is to small to be measured.
When 1 kg of petrol is burned the energy released is only 50 000 000 J corresponding to a decrease in mass of only 0,000 005 500 gram. This is to small to be measured and is omitted in chemical stoichiometry.

Natural exposures

Cosmic radiation:

The atmosphere protects against cosmic radiation. As the air gets thinner, radiation rises. Free protons as primary rays from outer space collide with the upper layers of the terrestrial atmosphere reacting with other particles. This causes a mixture of rays, like mesons which passes meter of concrete and weak rays such as electrons,positrons and gama rays.
Some examples demonstrate the growing exposition to radiation resulting growing air traffic. Passengers and crew of airlines are submitted to considerable high cosmic radiation. To spare fuel air traffic takes place at 10 000 o 20 000 meters over sea level:

Altitude(meters) Cosmic radiation (mrem/year)
sea level 30
1 500 60
3 000 140
4 000 200
   
Air traffic 0,5 mrem/flight hour
  (4 320 mrem/year)

A crew member with 80 flight-hours per month is exposed to 480 mrem/year, this is twelve times the exposure of a profession at sea level.

Exposition to radon:

The lung of inhabitants in cold climates are exposed to radiation of radon which emanates from soil and concentrates in poor change of air. This may lead to an exposition of the air tract and lungs of:

exposition to radon = 400 to 1 300 mrem/year

The radiation of radon ( $^{^{220}}_{_{86}}Rn$) is significant because it consists of alfa particles which cause great damage to surface cells. The volume of air which passes the lungs is very high. Intake of radon is therefore relevant. Keep rooms well aerated to get rid of radon.

Lung cancer caused by radioactive radon in living spaces

[1634]
The latest findings on the risk of lung cancer from radon exposure were discussed at the International Commission on Radiological Protection (ICRP) Berlin, 19 June 2007. According to Dr. Margot Tirmarche, the risk of radon-related lung cancer in habitations increases by around 8% per 100 Becquerel per cubic metre (Bq/m$^{3}$).

Additional cases of cancer are already observed at between 100 and 200 Bq/m$^{3}$. Every year in Germany around 1,800 people die due to radon - one person every four hours. Radon may also play a role in child leukaemia. There is an urgent need for action to reduce radon exposures. The target value for new buildings is 100 Bq/m$^{3}$, a guideline value for remediation work in existing buildings is 200 Bq/m$^{3}$.


Artificial radioactivity

Radioactive nuclides which do not occur in nature can be produced by bombarding natural occurring nuclides inside a nuclear reactor with atomic particles such as neutrons.

Nuclear reactor

Nuclear reactors try to provide electric energy with the claim of clean energy. Today Germany tries to get rid of the atomic industry as it proved to be unsafe and there is no solution for the disposal of nuclear waste.

Nuclear fission

is the disintegration of a heavy nucleus into two lighter nuclei with release of energy because the binding energy per nucleon of the fission products is greater than that of the parents.
A classic example of fission is the bombardment of uranium-235 ( $^{^{235}}_{_{92}}U$) by slow neutrons and the formation of $^{^{236}}_{_{92}}U$ which is unstable and undergoes fission.
$^{^{235}}_{_{92}}U$ + ( $^{^{1}}_{_{0}}n$)-> $^{^{236}}_{_{92}}U$ -> $^{^{141}}_{_{56}}Ba$ + $^{^{92}}_{_{36}}Kr$ + 3 $^{^{1}}_{_{0}}n$ + energy
Nuclear reaction make use of controlled fission reactions to provide energy. The atom bomb makes use of an uncontrolled fission reaction.


Nuclear fusion

is the combining of two light nuclei to produce a heavier nucleus and energy.
A classic example of nuclear fusion is the fusion of two deuterium nuclei to produce helium 3.
$^{^{2}}_{_{1}}H$ + $^{^{2}}_{_{1}}H$ -> $^{^{3}}_{_{2}}He$ + $^{^{1}}_{_{0}}n$ + energy
This is the source of energy of the sun.
The high pressure and high temperature which is necessary to overcome the mutual electrostatic repulsion in the hydrogen bomb is provided by an atom bomb.

The thermal reactor:

Uranium-236 being bombarded by neutrons undergoes a fission and releases about 2,5 neutrons which can bombard other uranium-236 atoms turning to a chain reaction.
In natural uranium only about 1 atom is a $^{^{235}}_{_{92}}U$ atom. All other atoms are $^{^{238}}_{_{92}}U$ which can only be fissioned with very fast neutrons. To produce fission of $^{^{235}}_{_{92}}U$ atom slow neutrons are necessary. Therefore the neutrons released by $^{^{235}}_{_{92}}U$ atom are to slow to cause fission of $^{^{238}}_{_{92}}U$ atom and to fast for a $^{^{235}}_{_{92}}U$ atoms. Therefore they must be slowed down by moderators ( graphite, water or heavy water D$_{2}$.). According to the material of the moderator the reactors are called:


Graphite-moderated reactor:

Control rods of boron coated steel are used to keep the rate of production of neutrons to the requiredrods level by capturing the necessary proportion before they can initiate fission.
The produced energy is removed with a coolant such as carbon dioxide or water though the reactor, passing through an heat exchanger producing steam to drive turbines.

Cycle of the fuel rods of nuclear power plants

Uranium is being won from ore in 99,3% U-238 and 0,7% U-235. This mixture is tranformed in gas as Uranium hexa fluorid (UF$_{6}$) in the special enrich plant. The amunt of U-235 is risen to 3,5% which is necessary for the function of light water reactors. Here the Uranium is formed to rods which arre then forwarded to the nuclear power plants.
The fuel rods once exhauted are stored until the separation of Uranium and Plutonium and other materials can take place. Waste of recycling is stored being protected by a glas layer.

Cancers in nuclear power plant workers

[1634]
According to Dr. Elisabeth Cardis) speaking at the Conference of the International Commission on Radiological Protection (ICRP) Berlin, 19 June 2007, the impact of low exposures has been underestimated in the past in two respects. The relative radiation risk in the area of occupational radiation exposure is definitely comparable to that of high exposures.

Increased rates of cancer are already observed in the case of occupational lifetime doses which comply with the limit values currently in force. Lowering the limit values must be investigated as a matter of urgency.

Leukemia in children living near nuclear power plants

[1635]
The German Federal Agency for Radiation Protection says that there is an increased leukemia risk for children living in the proximity of 5 kilometres from a nuclear power station. The risk increases inversely to the distance to the plant. A research study leaded by Dr. Maria Blettner , analysed all leukemia cases in the proximity of 16 German nuclear power plants from 1980 to 2003. The researchers found 37 new cases while only 17 had been statistically expected. One member of the team said that the results were underrated. He says the area of concern is to increase to 50 kilometres around nuclear power plants.

The study says that the emission of radiation of the nuclear power plants is not sufficient to cause to increase the risk of cancer, also other concurrent causes could not explain the association of increased leukemia risk with inverse distance to the nuclear power plant.

Worldwide studies confirm increased risk of leukemia in children under 5 years. The study of Dr. Blettner was done at The Institute of Medical Statistics, Epidemiology and Informatics (IMBEI) at the Clinical Centre of Mainz University.

The study rises high doubts on the veracity of foregoing studies which deny any increased cancer risk related to nuclear power plants.

The Federal Minister for the Environment Sigmar Gabriel asked the Radiation Protection Commission to assess the study, which is part of the German Children Cancer Register.

Japanese nuclear power plants are not earthquake safe

[1636]
The Japanese Nuclear power plant in Kashwazaki was seriously damaged by the 6,8 heavy earthquake on the 16. July 2007. The earthquake was 2,5 stronger as the plant was built for. Radioactive liquid was released at the site which is going through repair works for one year. There are another 17 nuclear power plants with the same guidelines used for the Kashwazaki plant.

Uranium-238 and ammunition in warfare

Uranium-238 is a waste of the production of fuel cells for nuclear power plants. As waste it is forwarded to the arms industry which uses it for hard core projectiles, mines and grenades.
Depleted uranium-238 (DU) projectiles were used to bust tanks in the desert of Kuwait and Iraq. From the 24.2.1991 to the 28.2.1991 around 315.000 kg of radioactive uranium fired against Sadams soldiers are now scattered all over the region.
Later, in the war against Milosewich in Kosovo almost the same amount of depleted uranium-238 was used and is still distributed all over the territory. This material is highly radioactive with a half-life of 4,5 billions of years.
All efforts should be done to avoida growing contamination of nature as there alternatives to uranium (density=18,7 Kg/dm$^{3}$ with traces of plutonium which can be replaced by tungsten (density=19,3 Kg/dm$^{3}$).

20 years after Chernobyl

[1637]
The accident of Chernobyl in 1986 is still responsible for sheep at the farms in Cumbria, Scotland and Wales in April 2006 to still contain levels radioactivity above safety limits. Their meat is not allowed to enter the food chain.

The particular chemical and physical properties of the peaty soil types of these regions makes the radiocaesium-137 to pass from soil to grass, accumulating in sheep.

The levels of radioactivity have fallen in some of the affected areas but a number of farms are still under restriction and will not have their restrictions lifted in the near future.

According to FEPA only sheep that have less than the maximum limit of 1,000 becquerels per kilogram of radiocaesium are allowed to enter the food chain.

Incorporation of radionuclides from the disaster of Chernobyl are increasing. Protective measures will be necessary for many generations

[1638]
Nesterenko and colleagues 2009 report that radiation levels for individuals in Belarus, Ukraine, and Russia have been increasing steadily since 1994 due to internal absorption.

To reduce levels of incorporated radionuclides in food and meat production food additives are used, such as ferrocyanides, zeolites, lime/Ca as an antagonist of Sr-90, K fertilizers as antagonists of Cs-137, and phosphoric fertilizers that form a hard, soluble phosphate with Sr-90, disk tillage and replowing of hayfields, cleaning cereal seeds, processing potatoes into starch, processing carbohydrate-containing products into sugars, and processing milk into cream and butter. Forestry operations to create "a live partition wall," to regulate the redistribution of radionuclides into ecosystems are discussed. The authors conclude that these protective measures will be necessary in Europe for many generations.

Contamination of food and people

[1639]
In many European countries levels of I-131, Cs-134/137, Sr-90, and other radionuclides in milk, dairy products, vegetables, grains, meat, and fish increased drastically after the catastrophe. Some foodstuffs from Europe exceeded permissible levels of Cs-137 in 2007. From 1995 to 2007, up to 90% of the children from Belarus had levels of Cs-137 accumulation higher than 15-20 Bq/kg, with maximum levels of up to 7,300 Bq/kg in Narovlya District, Gomel Province. Average levels of incorporated Cs-137 and Sr-90 in the heavily contaminated territories increased from 1991 to 2005. According to Nesterenko these areas will remain dangerously radioactive for the next three centuries.

Preventive Protective Action Guidelines

[1640]
The Protective Action Guides are 5 mSv (0.5 rem) for committed effective dose equivalent or 50 mSv (5 rem) committed dose equivalent to an individual tissue or organ, whichever is more limiting. These correspond to the "intervention levels of dose" consensus values set by international organizations. Intervention levels of dose are radiation doses at which introduction of protective actions should be considered (ICRP 1984b).

Limit Responder Exposure - 5 rem (or greater), sheltering - 1 to 5 rems. Evacuation - 1 to 5 rems. Relocation - 2 rems in first year, 500 mrem/yr in subsequent years, food Interdiction - 500 mrem/yr, drinking Water - 500 mrem/yr.

The US EPA response levels for preventive Protective Action to Land Contamination Guides (PAGs) are 3 μCi/m2 (111 kBq/m2) while levels for emergency PAGs are set at 30 μCi/m2 (1,110 kBq/m2) for infants and 50 μCi/m2 (1850 kBq/m2) for adults. Inhaled Cesium-137 commits to humans a 50-year committed effective dose equivalent (CEDE50) of 8.63×10-9 sievert per becquerel while its specific activity is 3.26×1012 becquerel per gram. [1641]

The mean contamination of Cs-137 in Germany after Chernobyl was 2000-4000Bq/m², some parts in the south even 10 times higher. This corresponds to a contamination of 1mg of Cs-137 per square kilometer or around 500g Cs-137 deposited all over Germany.

Fallout of Chernobyl affected Europe, Asia and Emirates

[1642]
Fall out of the Chernobyl meltdown affected 40% of Europe (including Austria, Finland, Sweden, Norway, Switzerland, Romania, Great Britain, Germany, Italy, France, Greece, Iceland, Slovenia) and wide territories in Asia (including Turkey, Georgia, Armenia, Emirates, China), northern Africa, and North America. Radioactivity exposure at a level higher than 4 kBq/m(2) (0.11 Ci/km(2)) from April to July 1986 happened. The consequences of radioactive contamination are therefore not confined to Belarus, Ukraine, and European Russia.

Interference level for radiation protection and decorporation of radionuclides

[1643]
Due to local food consumption the annual individual dose limits in Belarus, Ukraine, and European Russia exceed 1 mSv/year in 2007, and for effective radiation protection the interference level for children at should be set at 30% of the official dangerous limit (i.e., 15-20 Bq/kg), says Nesterenko.

Pectin food additives from apples, currants grapes and seaweed, 5 g twice a day, reduced radionuclides in children by 30 to 40%, report the authors.

Radiological impact in Europe

[1644]
According to Leoniak, Zonenberg and Zarzycki 2005 the air at Chernobyl had been contaminated with about 5300 PBq radionuclide activity, and surface 137Cs activity was 37 kBq/m(2). The highest mean radiation dose per year for the whole body in the first year after the accident was in Bulgaria (760 microSv), Austria (670 microSv), Greece (590 microSv), and Poland 932 microS, while the lowest radiation dose was observed in Portugal (1.8 microSv) and Spain (4.2 microSv).

Persistent contamination with 137 Cs of Alpine lakes sediments

[1645]
Rezzoug and colleagues 2006 found that the region of the alpine lake Boréon at the southeast of France was contaminated with 137Cs fallout of the Chernobyl accident with at least 3.5 Bqcm(-2), more probably the double. The lake sediments still undergo a rather strong contamination by 137Cs and the external exposure impact was evaluated at 2 mSvy(-1) for 2002. Transuranics and fission products 90Sr, 137Cs, 238Pu, 239/240Pu and 241Am have been measured in Boréon lake sediment samples. These data enable future determination of the mass balances of the radiopollutants. Schertz and colleagues 2005 stress that this area is in a recreational area used by urban population. [1646]

Fish of Finnish lakes with high uptake of 137Cs

[1647]
Saxén and Ilus report continuously high concentrations of 137Cs in fish of two Finnish lakes due to a prolonged stay of caesium at a relatively high level in the water. There were differences between the two lakes found which was explained by a slow sedimentation rate, deficiency of potassium in water, a low pH and a swampy soil type of the catchment resulting in a higher content of 137 Cs of the water and its uptake by fishes in the lake Lake Siikajarvi compared with the Lake Vehkajarvi.

Radionuclide transfer to wood and food from forests

[1648]
Radionuclide transfer varies in space and time depending on deposition processes, soil type, land use, and resulting contamination in food products, the radionuclide transfer through food chains. Calmon and colleagues 2001 assessed the transfer of radionuclides of radiocaesium and radiostrontium to trees in forests which vary between T(ag) 10(-3)m(2)kg(-1) (dry weight). Tree foliage was usually 2-12 times more contaminated than trunk wood. The transfer of radionuclides to mushrooms varies from T(ag) 10(-3) to 10(1)m(2)kg(-1) (dry weight), for berries, typical values are around 0.01-0.1 m(2)kg(-1) (dry weight). Transfer of radioactive caesium to game animals, reindeer, moose birds and waterfowl reflect the soil and pasture conditions at individual locations. In wild boar the caesium activity concentration shows no decline because of its special feeding habits.

Radionuclides from soil to fruits

[1649]
Carini 2001 in a 2001 review writes that the transfer of radionuclides from soil to fruit is nuclide specific, depends on the type of soils and fruit plant species. Caesium has a higher transfer rate to fruits of woody trees and the transfer from soil to fruits of shrubs is higher for strontium in temperate areas. Caesium is higher in subtropical and tropical fruits and strontium, plutonium and americium, in the same fruits, are lower because of different soil characteristics, says the author.

Undeclared irradiated supplements

[1650] Dried aromatic herbs, spices and vegetable seasonings are the only foods that may be irradiated inside and outside Member States of the EU and sold freely within the EU.

Imported irradiated food must comply with EU labelling and documentation rules. They must have been irradiated at a facility approved by the European Commission. There are only few approved facilities outside the EU: three in South Africa, one in Turkey and one in Switzerland.

Testing food supplements the FSA found in 2003 that 50 per cent of food supplements in the UK had been irradiated or contain an irradiated ingredient, but are not labelled as such. Publication of the results was deferred until 2006 pending enforcement action by local authorities.

The Food Safety Authority of Ireland (FSAI) found that 25 per centre of dried noodle products contained ingredients that had been irradiated. They had not been labelled as such.

The US, South Africa, the Netherlands, Thailand and France, followed by about 50 adopted irradiation technology and use it on 60 products.

Currently regulations on food irradiation in the European Union:

WHO Technical Report on Irradiation of Food:

A World Health Organisation scientific report in 1999 found that irradiation posed no risk to human health:
Overall chemical change, as reflected either in the formation of a stable compound or the loss of a particular constituent, is quantifiable and relatively minor, requiring sensitive techniques to discern that a product had been irradiated.

In summary, the macronutrients - proteins, fats and carbohydrates - are not significantly altered in terms of nutrient value and digestibility by irradiation treatment. Among the micronutrients, some of the vitamins are susceptible to irradiation to an extent very much dependent upon the composition of the food and on processing and storage conditions.

From a nutritional viewpoint, irradiated foods are substantially equivalent or superior to thermally sterilized foods.

On the basis of the extensive scientific evidence reviewed, the report concludes that food irradiated to any dose appropriate to achieve the intended technological objective is both safe to consume and nutritionally adequate.

The experts further conclude that no upper dose limit need be imposed, and that irradiated foods are deemed wholesome throughout the technologically useful dose range from below 10 kGy to envisioned doses above 10 kGy." [1651]

Irradiated foods in EU [1652]

The irradiation of dried aromatic herbs, spices and vegetable seasonings is authorised in the EU (Directive 1999/3/EC of the European Parliament and of the Council of 22 February 1999 on the establishment of a Community list of food and food ingredients treated with ionising radiation In addition, 6 Member States have notified that they maintain national authorisations for certain foods in accordance with Article 4(4) of Directive 1999/2/EC.

Under Article 6 of Directive 1999/2/EC, any irradiated food or any irradiated food ingredient of a compound food must be labelled with the words "irradiated" or "treated with ionising radiation".

Approved food irradiation facilities in EU

Belgium:

IBA Mediris S.A. Irradiating shrimps, frog legs, herbs, frozen vegetables, cheese, eggs, poultry/game, meat, fish, dried fruit, starch, plasma, prepared dishes, total 5,8 Tons in 2004

Czech Republic:

Dried aromatic herbs, spices and vegetable seasonings, egg white, total 460 tons in 2004.

Germany: In 2004

there were four approved irradiation facilities in Germany:

Spain:

There were two facilities approved for the irradiation of food. No information concerning activities in 2004 were given.

France:

There were seven facilities approved for irradiation of food. In 2004 the following foods were irradiated: Herbs, spices and vegetable seasonings, frozen herbs, dried vegetables and fruits, gum arabic, casein, caseinates, mechanically recovered poultry meat, offal of poultry, frozen frog legs, shrimps, total of 1.800 Tonns.

Hungary:

In 2004 there was one facility. No informations were given.

Italy:

In Italy here was one facilty. No information was given.

The Netherlands:

There were two facilities. One in Ede and one in Etten-Leur. Irradiated foods in 2004 were: Spices and herbs, dehydrated vegetables, poultry meat (frozen) frog parts, egg white (cooled), Foods intended for export to third countries. Total in 2004 4 768 Tons.

Poland:

There were two approved facilities:

The United Kingdom:

It has one facility approved. No food was irradiated in 2004.

Labelling:

The Neatherlands reports that a total of 430 samples had been taken in the marketplace and analysed for irradiation. Of these 430 samples, 45 dietary supplements and spices proved to be irradiated. Only 2 of the irradiated samples were correctly labelled as such. No indication of the origin of the positive samples was given.

The information submitted shows that during 2004, 3,9% of samples were irradiated and not correctly labelled.

The infringements are unevenly distributed over product categories. Products imported from Asia, especially Asian-type noodles and dried prepared noodles, are particularly concerned. In addition, it should be noted that in 2004, there were no facilities in Asia approved by the European Community.

Differences between Member States regarding the results of controls could partly be explained by the choice of the samples and the performance of the analytical methods used. No reports from 2005 and 2006 are available.

Adhesion and internalization of pathogens in fresh produces reduce efficacy of sanitizers

[1653]
Lynch, Tauxe and Hedberg 2009 explain that widespread food borne outbreaks have their cause in the increasing consumption of fresh produce, changes in production and distribution. Adhesion of pathogens to surfaces and internalization of pathogens reduce the efficiency of conventional processing and chemical sanitizing methods. At the surface of fruits pathogens can build biofilms which protects them from sanitizers, or they invade the interior of the plants where they cannot be harmed.

To reduce these risks the authors suggest to improve the prevention of the contamination on the farm, during packing or processing. A terminal such as irradiation may improve safety of fresh produce. The authors call for more investigations on the causes of outbreaks to develop improved prevention strategies. Noah 2009, commenting this article stresses that the worldwide transport of fruits and vegetables may distribute pathogens over large areas. [1654]

Irradiation of fruits and Vegetables

[1655]
Arvanitoyannis and colleagues 2009 emphasizes that central processing of fresh fruits and vegetables turns irradiation technology interesting. The authors stress that gamma irradiation restrain potato sprouting, kills pests in grain, extends shelf life of fruit and vegetable shelf life.

To avoid high irradiation doses the "hurdle technology" may be useful. This strategy applies more than one technology to improve quality and shelf life. Furthermore, various methods for detection of irradiated foods, such as EPR, TL and Comet assay are discusses.

The impact and effectiveness of irradiation dose on the shelf life and microflora and sensory and physical properties of fish, shellfish, molluscs, and crustaceans were assessed by Arvanitoyannis and colleagues. The authors looked also at the synergistic effect of irradiation in conjunction with other techniques such as salting, smoking, freezing, and vacuum packaging. Again, methods to detect irradiation of fish and seafood are assessed. [1656]

Irradiation of spinach affects nutrients

[1657]
FDA approved the irradiation of fresh iceberg lettuce and spinach to kill E. coli 0157:H7 and Salmonella enteric. Doses of irradiation up to 4kGy had been considered not to impact the nutrients of spinach.

Lester and colleagues 2010 assessing the effect of gamma-irradiation or electron beams on spinach found that concentrations of vitamins B(9), E, and K and neoxanthin were little or not changed by irradiation. However, total ascorbic acid (vitamin C), free ascorbic acid, lutein/zeaxanthin, violaxanthin, and beta-carotene all were significantly reduced at 2.0 kGy and lesser doses. Dihydroascorbic acid increased with increasing irradiation due to the formation of oxidative radicals.

The authors report that packaging atmosphere had little effect, however, spinach irradiated under N2 presented an increase of dihydroascorbic acid levels, compared to air.

Irradiated foods are free of risks, but consumer is still insecure

[1658]
No scientific study demonstrating that consumption of irradiated food might pose a risk to consumers were found by Rossi and colleagues 2009. All studies conclude that food irradiation at the appropriate dose required to reduce contamination is safe and does not affect its nutritional value, however the technology is not accepted by a broad part of the consumers.

In an effort to demonstrate the potential benefits, the authors compared food irradiation with the risk of infection with E. coli 0157: H7, and concluded that up to date no risk of irradiated foods are known, but death cases from bacterial pathogens are known.

Escherichia coli internalized on lettuce leaves

[1659]
Gomes and colleagues 2009 assessed the efficacy of irradiation of leaves of iceberg, Boston, green leaf, and red leaf lettuces contaminated with a cocktail mixture of two isolates of Escherichia coli, and subjected to a vacuum perfusion process locate the bacteria on crevices and into the stomata.

Gamma irradiation was applied at 0.25-1.0-kGy. Calculated D(10)-values varied between 48 and 62%. No significant difference was noted between the lettuce varieties. Irradiation up to 1.0-kGy resulted in 3-4-log reduction of internalized E. coli on the lettuce leaves.

The authors concluded that ionizing irradiation may be used to reduce the risk of food disease outbreaks by reducing internalized pathogens. The effect is dose-dependent,

Irradiation compared with chlorination for elimination of Escherichia coli O157:H7

[1660]
Niemira 2008 comparing the effect of irradiation with that of chlorination found that pathogenic bacteria penetrate the leaf tissues and are protected against chlorination. In rhis study E. coli inoculated leaves of boston, green leaf, and red leaf lettuce were treated with a 3-min wash with sodium hypochlorite solution (0, 300, or 600 ppm) or various doses of ionizing radiation (0.25 to 1.5 kGy).

The reduction obtained with chlorine solutions was less than 1 log, while irradiation reduced pathogenic E. coli 5 logs on iceberg lettuce treated with 1.5 kGy. The variety of lettuce influences the specific results. The author concluded that irradiation is able to effectively reduce viable E. coli O157:H7 cells internalized in lettuce.

Irradiation of food, an emerging technology

[1661]
In a review in 1998 Farkas suggests the irradiation of food ranging from 2 to 7 kGy, depending on the variety of food, to eliminate potentially pathogenic. The author recommends irradiation of poultry and red meat, egg products, and fishery products, irradiation can be performed in frozen state. According to the author fumigation of herbs and enzyme preparations may be replaced irradiation using doses of 3-10 kGy. Radiation treatment at doses of 0.15-0.7 kGy are being suggested for the control of foodborn parasites. The author stresses that microorganisms surviving radiation treatment are more sensitive subsequent food processing treatments than not irradiated bacteria. The author concluded that irradiation of food is an emerging technology with increasing number of clearances on radiation decontaminated foods.

Improved safety and quality of poultry and other irradiated meat

[1662]
O'Bryan and colleagues 2009 emphasize that currently permitted levels of irradiation are insufficient to control pathogenic viruses, while gram-negative spoilage organisms are very sensitive to irradiation. The reduction of spoilage bacteria increased the shelf life and, on the other hand, did not provide a competitive growth advantage for other food pathogens, weakened by irradiation.

The authors stress that most of the antimicrobials and antioxidants produce an increased lethality of irradiation. Thus, the combinations of dosage, temperature, dietary and direct additives, storage temperature and packaging atmosphere can improve quality of meat.

Irradiation as food preservation method

[1663]
Andrews and colleagues 2008 stresses the use of irradiation in fruits and vegetables as an insect control as an alternative to less effective methods. For grains such as rice and wheat, irradiation has been used to control infestation by fumigation resistant insects. For spices irradiation doses of 10 kGy were recommended to extend shelf life. Safety of meat may be improve with irradiation, so as it is happening with seafood products such as shrimps for the Asian and European markets

Electron spin resonance (ESR) detection of irradiated food

[1664]
Electron spin resonance (ESR) may detect the radiation-induced radicals which persist, even after most of the radicals have decayed within days or weeks. Dodd 1995 calls it the most specific for the detection of irradiated food. Later, in 2008, Yu and Cheng provided a review of the use of this method used in nutraceutical and food research, microstructure change, phase transition and viscosity related properties during food formulation, processing, and storage. [1665] Electron paramagnetic resonance EPR method to detect irradiation of soybean [1666]
The gamma radiation dose in the 0.25 to 1.0 kGy range irradiation is permitted to control insect infestation of food. Sanyal and Sharma 2009 developed an electron paramagnetic resonance (EPR) spectrum method. The authors detected cellulose and phenoxyl radicals in the skin part of irradiated soybean. The authors suggest that that progressive saturation and thermal characteristics of induced radicals may be used to distinguish low doses irradiated soybean from thermally treated one. This method is applicable also in case of long storage, say the authors.

Relaxation behaviour of the radicals may be used to detect irradiation of cashew nuts

[1667]
In 2008 Sanyal and Sajilata assessed the electron paramagnetic resonance (EPR) spectrum of free radicals formed during irradiation and compared it with those caused by conventional thermal treatment of cashew nuts. These signals found at irradiated cashew nuts were related to cellulose and CO 2 (-) radicals. An increase of the intensity of the central line (g = 2.0045) was found to be similar to that of thermal treated cashew nuts. The authors report, however, that irradiation of cashew nuts could be demonstrated by measuring the different relaxation and thermal behaviours of the free radicals, compared with those of roasted cashew nuts.

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