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.
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.
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.
How much radiation is dangerous?
- 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.
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:
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
Overt stage: Depending on the type of exposure, this can involve problems with the cardiovascular, gastrointestinal, hematopoietic, and central nervous system (CNS)
Recovery or death: There may be a slow recovery, or the poisoning will be fatal.
Different doses, different effects
The risk of illness depends on the dose. Very low doses of radiation are all around us all the time, and they do not have any effect. It also depends on the area of the body that is exposed.
If the whole body is exposed to, say, 1,000 rads within a short time, this could be fatal. However, far higher doses can be applied to a small area of the body with less risk.
After a mild dose, the person may experience symptoms for just a few hours or days. However, a repeated or even a single, relatively low dose that produces few or no visible symptoms around the time of exposure may cause problems later on.
A person who is exposed to 3,000 rads will experience nausea and vomiting, and they may experience confusion and a loss of consciousness within a few hours. Tremors and convulsions will occur 5 to 6 hours after exposure. Within 3 days, there will be coma and death.
People who experience repeated doses, or who appear to recover, may have long-term effects.
- a loss of white blood cells, making it harder for the body to fight infection
- reduction in platelets, increasing the risk of internal or external bleeding
- fertility problems, including loss of menstruation and reduced libido
- changes in kidney function, which can lead to anemia, high blood pressure, and other problems within a few months
There may also be skin redness, cataracts, and heart problems.
Localized exposure may lead to changes in the skin, loss of hair, and possibly skin cancer.
Exposure to certain parts of the body is more dangerous than others, for example, the intestines.
The effects of radiation are cumulative. Damage to cells is irreversible.
Exposure to radiation can result from workplace exposure or an industrial accident, radiation therapy, or even deliberate poisoning, as in the case of the former Russian spy, Alexander Litvinenko, who was murdered in London by polonium 210 placed in his tea. However, this is extremely rare.
Most people are exposed to an average of around 0.62 rads, or 620 Gray each year.
Half of this comes from radon in the air, from the Earth, and from cosmic rays. The other half comes from medical, commercial, and industrial sources. Spread over a year, this is not significant in terms of health.
Levels of radiation from an x-ray are not high, but they occur at one moment.
- A chest x-ray gives the equivalent of 10 days' exposure to radiation
- Mammogram gives the equivalent of 7 weeks' normal exposure
- PET or CT used as part of nuclear medicine exposes a person to the equivalent of 8 years of radiation
- A CT scan of the abdomen and pelvis gives the equivalent of 3 years' normal exposure
Nuclear medicine is used to target the thyroid in people with a thyroid disorder. Other types of medical treatment include radiation therapy for cancer.
Living at a higher altitude, for example, in the plateau of New Mexico and Colorado, increase exposure, as does traveling in an airplane. Radon gas in homes also contributes.
Food, too, contains small amounts of radiation. The food and water we drink is responsible for exposure to around 0.03 rads in a year.
The many activities that can expose people to sources of radiation include:
- watching television
- flying in an airplane
- passing through a security scanner
- using a microwave or cell phone
Smokers have a higher exposure than non-smokers, as tobacco contains a substance that can decay to become polonium 210.
Astronauts have the highest exposure of anyone. They may be exposed to 25 rads in one Space Shuttle mission.
Damage by radiation is irreversible. Once the cells are damaged, they do not repair themselves. Until now, there is no way for medicine to do this, so it is important for someone who has been exposed to seek medical help as soon as possible.
Possible treatments include:
- Removing all clothing,
- Rinsing with water and soap.
- Use of potassium iodide (KI) to block thyroid uptake if a person inhales or swallows too much radioiodine
- Prussian blue, given in capsules, can trap cesium and thallium in the intestines and prevent them from being absorbed. This allows them to move through the digestive system and leave he body in bowel movements.
- Filgrastim, or Neupogen, stimulates the growth of white blood cells. This can help if radiation has affected the bone marrow.
Depending on exposure, radiation can affect the whole body. For cardiovascular, intestinal, and other problems, treatment will target the symptoms.
Reducing exposure to radiation
Tips for reducing unnecessary exposure to radiation include:
- keeping out of the sun around midday and using a sunscreen or wearing clothes that cover the skin
- making sure any CT scans and x-rays are necessary, especially for children
- letting the doctor know if you are or may be pregnant before having an x-ray, PET, or CT scan
It is not possible or necessary to avoid all exposure to radiation, and the risk posed to health by most sources is extremely small.