Radioactivity Demystified: From Basics to Advanced Insights

What are and where are the radiations?

Radioactivity is the property of some substances to emit ionizing radiation. Ionizing radiation are high-energy particles that are capable of altering and damaging molecules as they pass through matter.

Radioactive contamination and exposure to radioactivity occur when radioactive material is released into the atmosphere from sources such as a nuclear power plant or the explosion of an atomic bomb. There are also natural sources of radiation in land, water, and air.

What radiation do we normally receive?

We are usually exposed to natural radiation that exists from space and radioactive material that is in the land, water and air. Likewise, there are artificial sources of radiation, such as

According to data provided by the World Health Organization (WHO), a person receives about 3 millisieverts (mSv), the measure of radiation levels, throughout the year, which is considered a safe and tolerable amount. Exposure of less than 100 mSv per year generally does not pose any health risk or produce symptoms.

How does the body absorb them?

There are two ways, internal contamination and external irradiation. Internal contamination involves the entry of radioactive material through the digestive tract (contaminated food or water) or through the respiratory tract, while external irradiation occurs through exposure to external sources or by adhering radioactive material to the skin or clothing, which can be removed by washing the body.

What kind of effects does radiation have on the body?

Ionizing radiation has a great penetrating power so it can reach the most vulnerable part of a cell, the chromosomes that are in the nucleus of the cell. All ionizing radiation can produce biological changes in the molecules of organisms, either directly through different mechanisms, or indirectly through the formation of free radicals or agents that are harmful to health. Thus, ionizing radiation can cause damage both by interacting with organs and tissues and by affecting the genetic material of cells.

The effects that radiation exposure has on the human body are diverse. The repercussions depend on the distance at which each person is from the source of radiation emission, their sensitivity, the radiation dose received and the radioactive materials emitted.

What risks do they pose to health?

At higher doses of radiation, greater repercussions on health, as they can have consequences on the central nervous system, blood cells and the immune system.

The health effects of radiation are broadly divided into acute and chronic.

Acute effects occur immediately and are burns, hair loss and a number of symptoms (acute radiation syndrome) produced by a high radiation dose (> 1000 mSv). The irradiation syndrome occurs after irradiation emitted by an external source that reaches the whole organism acutely and in a short space of time. It gives rise to alterations in the bone marrow (in the production of blood cells), symptoms at the level of the gastrointestinal system and the central nervous system.

In contrast, chronic or long-term effects are seen after months or years and can persist for a long time. It mainly increases the risk of developing cancers (such as thyroid cancer) and suffering from congenital malformations. This is because ionizing radiation causes changes in DNA, which contains the organism's genetic information, causing mutations in that information, mutations that can have effects on subsequent generations.

Why are iodine pills given?

Special mention should be made of the thyroid problems caused by the accumulation of radioactive iodine. One of the most dangerous components that can be found in a nuclear reactor is radioactive iodine, which, when absorbed by the body, tends to accumulate in one of the organs most sensitive to radiation, the thyroid gland. This gland usually captures iodine from the diet to perform its function. When the iodine taken up by the thyroid is radioactive, it accumulates in the gland, which can cause thyroid cancer.

Therefore, it is recommended to ingest iodine and thus block the fixation by the thyroid of radioactive iodine. In case of having been exposed to high radiation, potassium iodide tablets are administered, which aim to prevent damage to the thyroid.

Who are most vulnerable to radiation?

The population most vulnerable to radiation are children, as the younger the age, the greater the radiation sensitivity.

What are the general preventive measures?

In the event of a nuclear accident or any other phenomenon that causes a risk of radiation, the measures to be taken include:

• Establish security perimeters and evacuate the population to the calculated distance where it is expected that they will be free from the effects of radiation, protection in shelters to reduce exposure and administration of iodine tablets when indicated by the competent authorities.
• Follow the measures established by official agencies and sources.
• In certain cases, in which it is justified, the consumption of certain food products (which may be contaminated), going out into the street and other measures such as hanging clothes outside will have to be limited.