• What is radiation sickness?
• What is a high dose of radiation?
• What types of radiation do I have to worry about?
• What types of radiation sickness are there?
• How is radiation sickness treated?
• How dangerous is it?
• What's the difference between exposure and contamination?
• How is contamination spread?
• How much radiation exposure is normal?
• How much is dangerous?

Alexander Litvinenko

On Aug. 6, 1945, an American warplane dropped a nuclear bomb on the Japanese city of Hiroshima. An estimated 80,000 people were incinerated. In the months that followed, another 60,000 died from the effects of radiation.

Thousands of others died later of diseases linked to the bombing.

In April 1986, an explosion at the nuclear reactor in Chornobyl, Ukraine, killed two workers. But in the days that followed, more than 30 lives were snuffed out from radiation exposure. The International Atomic Energy Agency's Chornobyl Forum later said at least 4,000 people died, or would die, from radiation-induced cancers. The World Health Organization estimated that 9,000 would succumb to illnesses linked to radiation released by the blast.

And in November 2006, former Russian spy Alexander Litvinenko died in a London hospital after eating a sushi dinner with a contact. Before he died, he accused the Russian government of poisoning him. After his death, a British probe found traces of radiation at roughly a dozen sites in the country and a number of jets were being investigated.

What is radiation sickness?

Radiation sickness — known as acute radiation syndrome (ARS) — occurs after exposure to a large amount of radiation within a short period. Early symptoms can include skin irritation, nausea, vomiting, high fever, hair loss and burns to the skin. Other symptoms can include diarrhea, weakness, fatigue, loss of appetite, fainting, dehydration, inflammation of tissues, bleeding from the nose, mouth, gums or rectum, and anemia. People exposed to radiation will get ARS only if:

• The radiation dose was high.
• The radiation was penetrating, reaching internal organs.
• The person’s entire body, or most of it, received the dose.
• The radiation was received in a short time, usually within minutes.

The first symptoms will start within minutes to days after exposure and may come in waves, with a seriously ill stage lasting from a few hours up to a few months. People with radiation poisoning will generally show skin damage within a few hours of exposure. This can include swelling, itching and a redness of the skin, similar to a sunburn.

What is a high dose of radiation?

High is relative. All of us are exposed to radiation on a regular basis. Every time you get an X-ray, you are exposed to radiation. There may be more radon gas in your basement than there should be — but it might not be enough to make you sick, unless you're exposed to it for decades. But doses from radiation therapy to treat cancer may be high enough to cause some ARS symptoms.

Even a minuscule amount of certain materials can result in exposure to a high dose of radiation. Traces of polonium-210 were found in the urine of former Russian spy Alexander Litvinenko, who died in a London hospital on Nov. 23, 2006. He accused the Russian government of poisoning him to silence him. Litvinenko fell ill shortly after eating a sushi dinner with a contact.

As polonium-210 decays, it gives off a great deal of energy. A half-gram will reach a temperature of 480 C quickly. A very small amount would make you very sick.

What types of radiation do I have to worry about?

There are two major types of radiation: penetrating (ionizing) radiation and non-penetrating (non-ionizing) radiation.

Penetrating radiation enters the body and deposits high energy into tissues, which can cause cell damage or cell death. A large dose of penetrating radiation can kill bone marrow cells and eventually cause death.

Non-penetrating radiation does not pass through the skin, but can still cause severe damage. A large dose of non-penetrating radiation can burn the skin similar to a severe sunburn.

Radiation can be made up of three different components:

• Alpha particles are the least penetrating and are not considered dangerous unless ingested. Alpha particles are emitted by radioactive nuclei such as uranium or radium. As they decay, they give off energy.
• Beta particles can penetrate the skin, causing skin damage and harm to internal organs if ingested. Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40.
• Gamma rays have great penetrating power. They are described as light with the highest frequency and energy within the light spectrum. Gamma rays are high- energy ionizing radiation that cause skin burns, severely injure internal organs and cause long-term effects.

What types of radiation sickness are there?

There are two main types, chronic and acute:

• Chronic radiation sickness may take several days or weeks to develop. The cause can be radioactive fallout from a nuclear explosion, an industrial accident or long-term exposure to elevated radiation levels. Therapeutic radiation treatments for cancer also can cause temporary chronic radiation sickness. Chronic exposure may increase your risk of cancer, precancerous lesions, benign tumors, cataracts, skin changes and congenital defects.
• Acute radiation sickness can develop quickly. A person with acute radiation sickness usually has been exposed to large amounts of radiation over a brief period. Extremely high levels of acute radiation exposure can result in death within a few hours, days or weeks, depending on the dose. Proximity to a nuclear explosion or an industrial accident could lead to acute radiation sickness — as would being intentionally poisoned with radioactive material.

Either way, the higher the level of radiation exposure, the lower the chance of survival.

A very high dose of radioactive materials would need to be ingested or inhaled to cause damage. Radiation generally has a very short range, so it only harms nearby tissue. Your whole body would need to be exposed, and the high dose (more than 1,000 millisievert) would have to be received in a short time, like a few minutes.

How is radiation sickness treated?

Treatment for radiation sickness is designed to help relieve its signs and symptoms. It won't reverse the effects of radiation exposure.

Doctors may use anti-nausea drugs and painkillers to relieve some signs and symptoms, and antibiotics to fight off secondary infection. Blood transfusions may be needed to treat anemia.

Patients treated for exposure should expect to be monitored over the long-term.

How dangerous is it?

The chance of survival for people with radiation poisoning decreases with increasing doses of exposure. The cause of death in most cases is the destruction of the bone marrow, which results in infections and internal bleeding.

What's the difference between radiation exposure and contamination?

A person exposed to radiation is not necessarily contaminated with radioactive material. You're exposed to radiation every time you have an X-ray, but to be contaminated, the radioactive material must be on or inside the body. A contaminated person is exposed to radiation released by the radioactive material on or inside the body.

An uncontaminated person can be exposed by being too close to radioactive material or a contaminated person, place, or thing.

Exposure to radiation before birth can increase the risk of developing cancer later in life.

How is contamination spread?

People who have been exposed can contaminate other people or surfaces. For example, people who have radioactive dust on their clothing may spread the dust when they sit in chairs or touch other people. People who are internally contaminated, meaning they've been penetrated by waves of radiation, can spread it through their body fluids like blood, sweat and urine.

How much radiation exposure is normal?

People in North America are exposed, on average, to between two and four mSv each year from natural sources.

This exposure comes from food, water, sunlight, tobacco, televisions, X-rays, smoke detectors and building materials.

How much is dangerous?

Any amount of radiation can be dangerous because it can disrupt normal cell processes. But at low doses, the body can replace any cells that die because of exposure.

At high doses, the body can't replace the dying cells fast enough and tissues and organs may begin failing. To get light radiation sickness symptoms, you would need to be exposed to more than 1,000 mSv of radiation within a short time.

The dose from an X-ray is too low to cause radiation sickness, while doses from cancer treatments might be high enough to cause some symptoms. Emissions from cellphones and microwaves are also low.