Radiation sickness: Sources, effects, and protection

Radiation is used in medicine, to generate electricity, to make food last longer, to sterilize equipment, for carbon dating of archeological finds, and many other reasons.

Ionizing radiation happens when the atomic nucleus of an unstable atom decays and starts releasing ionizing particles.

When these particles come into contact with organic material, such as human tissue, they will damage them if levels are high enough, in a short period of time. This can lead to burns, problems with the blood, gastrointestinal system, cardiovascular and central nervous system, cancer, and sometimes death.

Radiation is normally managed safely, but its use also entails a risk.

If an accident happens, for example, the earthquake in Fukushima, Japan, in 2011, or the explosion at Chernobyl, Ukraine in 1986, radiation can become dangerous.

Fast facts on radiation sickness:

Here are some key points about radiation sickness. More detail is in the main article.

Radiation is all around us and it is used safely in many applications.

Nuclear accidents, the work environment, and some medical treatment can all be sources of radiation poisoning.

Depending on the dose, the effects of radiation can be mild or life-threatening.

There is no cure, but barriers can prevent exposure and some medications may remove some radiation from the body.

Anyone who believes they have been exposed to radiation should seek medical attention as soon as possible.

What is radiation sickness?

Radiation has many uses, but it can be dangerous if it is not managed correctly.
Radiation has many uses, but it can be dangerous if it is not managed correctly.

Radiation poisoning happens when a radioactive substance gives off particles that get into a person’s body and cause harm. Different radioactive substances have different characteristics. They can harm and help people in different ways, and some are more dangerous than others.

Normally, radiation occurs in a safe environment. Whether or not it becomes dangerous depends on:

how it is used

how strong it is

how often a person is exposed

what type of exposure occurs

how long exposure lasts

A dose of radiation from a single x-ray is not normally harmful. Nevertheless, the parts of the body that are not being x-rayed will be shielded with a lead apron to prevent unnecessary exposure.

The technician, meanwhile, will leave the room when taking the image. While one small dose is not dangerous, repeated small doses could be.

A sudden, short, low dose of radiation is unlikely to cause a problem, but extended, intense, or repeated doses can be. When radiation damages cells, it is irreversible. The more often a person is exposed, the greater their risk of health problems.

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How much radiation is dangerous?

Radiation dosage can measured in various ways. Some of the units used are Grays, Sieverts, rems, and rads. They are used in a similarway, but 0.1 rad is equivalent to 100 Gray.

Below 30 rads: Mild symptoms will occur in the blood

From 30 to 200 rads: The person may become ill.

From 200 to 1,000 rads: The person may become seriously ill.

Over 1,000 rads: This will be fatal.

According to the Centers for Disease Control and Prevention (CDC), radiation sickness, or acute radiation syndrome (ARS) is diagnosed when:

A person receives over 70 rads from a source outside their body

The dose affects the whole body, or most of it, and is able to penetrate to the internal organs

The dose is received in a short time, usually within minutes

A person who experiences an atomic explosion will receive two doses of radiation, one during the explosion, and another from fallout, when radioactive particles float down after the explosion.

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Radiation sickness can be acute, happening soon after exposure, or chronic, where symptoms appear over time or after some time, possibly years later.

The signs and symptoms of acute radiation poisoning are:

vomiting, diarrhea, and nausea

loss of appetite

malaise, or feeling unwell


rapid heartbeat

Symptoms depend on the dose, and whether it is a single dose or repeated.

A dose of as low as 30 rads can lead to:

loss of white blood cells

nausea and vomiting


A dose of 300 rads dose may result in:

temporary hair loss

damage to nerve cells

damage to the cells that line the digestive tract

Stages of radiation sickness

Symptoms of severe radiation poisoning will normally go through four stages.

Prodomal stage: Nausea, vomiting, and diarrhea, lasting from a few minutes to several days

Latent stage: Symptoms seem to disappear, and the person appears to recover

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