The sources of natural radionuclides
Radionuclides affect all biological species regardless of their habitat and environment. But if the degree of exposure of wild animals applies to us only in part, the nuclides in the organism of domestic animals have the potential to become “property” of man.
The accumulation of radioactive substances in the body of a pet.
The main way that radioactive substances enter into the body of a pet is contaminated food and water. It is not excluded the penetration of radionuclides through the respiratory system and skin. The rate of accumulation of radioactive substances and their transition into their milk, meat, eggs and derived products depends on several factors:
the type, age and functional status of the animal;
physical and chemical properties of the radionuclide;
the time and intensity of exposure.
If the body of the animal radionuclides entered only once, their excretion from the body will happen quickly and without accumulation. In the case of prolonged exposure, the radionuclides from the gastrointestinal tract of the animal penetrate into tissues and organs. While initially there is an intensive accumulation, and then comes the so-called state of equilibrium, in which the ongoing postpresidential already does not change their concentration in the direction of increasing.
Ways of migration of radionuclides from animal to man are:
milk and dairy products;
To reduce the transition in the animal body, and hence further penetration in the human body can be through the organization of keeping and feeding domestic animals.
The removal of radionuclides from milk
Milk allowed in large compared to other radioactive materials quantities, migrate: strontium, cesium and iodine as the predominant radionuclide in the list. In large animals the excretion with milk is about 7%, whereas in the thyroid gland accumulates, approximately 10-20%, for small animals (goats and sheep) the above indicators are equal in terms and are in the range of 30-40%. This suggests that the content of iodine in milk 131,135 small animals is much higher.
At risk of this type of migration of radioisotopes from domestic animals to humans are primarily pregnant and lactating women, children, and inhabitants of regions where dairy production is the main agricultural activity.
Separation of milk, is recognized as an effective tool in allowing 10 or more times to reduce the content of radionuclides. After separation of the resulting cream can be diluted to the initial level of fat. Serum remaining after processing, for food not consumed.
Migration of radionuclides with meat
Meat plays a major role in the contamination of food with radionuclides. But a knowledge of the principles of their accumulation, physico-chemical properties and timing of breeding allows you to calculate the age of the animal at which the meat will be most secure for consumption.
The main radioactive substance contained in the meat – cesium-137 and strontium-90. Their distribution in the animal body is uneven. Cesium-137 is largely accumulated in the soft tissues, and the opposite strontium contained in bone, the excretion of which occurs very slowly.
Research different types of meat (pork, beef, venison, lamb) on the content of cesium-137 have shown that its maximum concentration in venison (10 times more compared with other sorts of meat), followed by mutton, and beef, the level of cesium-137, lower in 2 times than in the lamb. The least content of this radionuclide in pork (3 times lower than in the lamb).
To reduce the content of radioactive substances in the meat in several ways:
salting in brine – this method involves cutting the meat in small pieces and frequent change of the brine;
by soaking in salt brine with the addition of ascorbic acid or vinegar;
a decoction with the indispensable change of the broth after 10 minutes after boiling.
Radionuclide migration with eggs
Compared with milk or meat, eggs have a much smaller total amount withdrawn from the body of the poultry radioactive substances and constitute only a hundredth of a percent from the society of the received radionuclides. Their distribution is uneven, and suppressing the part of radioactive materials is in the shell. Thus, the more time the term masonry is separated from the penetration of radionuclides into the body of the bird, the less penetrates through the shell inside the eggs. Accordingly, the percentage of radionuclides in the shell compared to all derived – increases.
Conducted radiochemical analyses it was found that the eggs from the body of the bird is displayed: strontium, cesium-137, barium and iodine 131. Barium and strontium are localized in the shell, cesium 137 in a greater proportion is contained in the protein, the yolk is the place of concentration of iodine 131. It should be noted that when cooked, the radionuclides concentrated in the shell are transferred to the egg, so boil them without the shell recommended or pre-steeping in salt brine with the addition of citric acid, which will absorb partially contained in the shell of a radioactive substance.