A contaminated object will be radioactive for as long as the source is on or in it. Can be blocked from the object with suitable shielding. Once an object is contaminated, the radiation cannot be blocked from the object. Stops as soon as the source is removed. It can be very difficult to remove all of the contamination. Ask the Experts is posting answers using only SI the International System of Units in accordance with international practice.
To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here. Answer posted on 13 August The information posted on this web page is intended as general reference information only. This kind of thinking involves seeing the radiation as somehow becoming stored inside the absorber I think that radiation would be left inside the food such that it can be re-released later.
However, please be aware that irradiation with neutrons can result in nuclear changes, perhaps producing unstable nuclei. That's what the careful is all about in the right lines quote — don't choose a radiation that can trigger nuclear changes. This teaching and learning challenge takes us back once again to stressing the difference between irradiation and contamination. Teacher: Cobalt—60 is commonly used in food irradiation. This source emits gamma radiation, which acts to kill any bacteria, viruses or insects on the food.
The gamma radiation also irradiates the food and although there may be small chemical changes, it can't make the food radioactive.
It's not as though any cobalt—60 is left on the food. Such a release could expose people and contaminate their surroundings and personal property. Internal contamination occurs when people swallow or breathe in radioactive materials, or when radioactive materials enter the body through an open wound or are absorbed through the skin. Some types of radioactive materials stay in the body and are deposited in different body organs.
Other types are eliminated from the body in blood, sweat, urine, and feces. Radioactive contamination occurs when radioactive material is deposited on or in an object or a person. Radioactive materials released into the environment can cause air, water, surfaces, soil, plants, buildings, people, or animals to become contaminated. A contaminated person has radioactive materials on or inside their body.
People who are externally contaminated with radioactive material can contaminate other people or surfaces that they touch. For example, people who have radioactive dust on their clothing may spread the radioactive dust when they sit in chairs or hug other people.
People who are internally contaminated can expose people near them to radiation from the radioactive material inside their bodies.
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