Speaker 1: Welcome to brain stuff from how stuff works. Hey, I'm
Speaker 1: Christian Segar, and this is brain stuff for most people.
Speaker 1: Ionizing radiation isn't something we need to worry about, but
Speaker 1: some unexpected events can make us sick from radiation, like
Speaker 1: nuclear power plant accidents, atomic bombs, leaks, and medical or
Speaker 1: industrial devices, or acts of terrorism. And what we know
Speaker 1: about severe radiation sickness is from incidents like these. So
Speaker 1: radiation it's actually everywhere. It's in the atmosphere, the ground,
Speaker 1: the water, and even our own bodies. We call this
Speaker 1: natural background radiation and it's perfectly safe. Radiation strips electrons
Speaker 1: away from atoms, creating a positively charged atom called an ion. Therefore,
Speaker 1: high energy radiation is called ionizing radiation. Releasing the electron
Speaker 1: produces thirty three electron volts of energy, and this heat
Speaker 1: surrounding tissue and disrupts some chemical bonds. Extremely high energy
Speaker 1: radiation can destroy the nuclei of atoms, releasing even more
Speaker 1: energy and causing more damage. The resulting radiation sickness is
Speaker 1: a cumulative effect of all of this damage on a
Speaker 1: human body bombarded with radiation. Now, radiation exposure is measured
Speaker 1: in units called milarem or m REM. Higher readings are
Speaker 1: measured in ms V, which are multiples of one hundred mrem.
Speaker 1: In the US, we get an average annual dose of
Speaker 1: three hundred and sixty m rem. More than eight percent
Speaker 1: comes from natural background radiation, and there are three kinds
Speaker 1: of ionizing radiation. Alpha particles are the first, and they're
Speaker 1: the least dangerous. They don't penetrate deeply into our skin
Speaker 1: if they do at all, because clothes can stop the particles,
Speaker 1: but they can be inhaled or ingested, usually as a
Speaker 1: raid on gas, and they can also lead to lung cancer.
Speaker 1: Beta particles are another one. These are when electrons move
Speaker 1: quickly with a lot of energy. There are eight thousand
Speaker 1: times smaller than alpha particles, so they can penetrate the
Speaker 1: skin and this can burn us or cause tissue damage.
Speaker 1: Beta particles can be ingested if they enter food or
Speaker 1: water supplies. And then we've got the most dangerous, which
Speaker 1: are gamma rays, extremely high energy that travels through matter.
Speaker 1: Since they have no mass, these can be only blocked
Speaker 1: by several inches of lead or concrete. If you're exposed
Speaker 1: to them, they run through your whole body, affecting the
Speaker 1: tissue and even the marrow of your bones, and these
Speaker 1: cause widespread systemic damage. So how does radiation make a
Speaker 1: sick Well, it deposits energy into our tissue, causing cell damage,
Speaker 1: and this can make our cells abnormal or malignant. Huge
Speaker 1: amounts of radiation and kill within days or hours in
Speaker 1: acute exposure and frequent exposure to low doses over long
Speaker 1: periods is called chronic exposure. This causes a delay in
Speaker 1: those health effects. However, when we're talking about amounts of
Speaker 1: radiation needed to trigger radiation sickness symptoms, it's in terms
Speaker 1: of total dosage, and this also takes into account radiation intensity,
Speaker 1: how much is absorbed into the human body, how long
Speaker 1: the exposure is, and the types of radiation involved. And
Speaker 1: this is quantified as the c vert, measured by the
Speaker 1: absorption of energy multiplied by the radiation type. So, for instance,
Speaker 1: a ct scan is equal to point zero one siverts
Speaker 1: of radiation. Now, federal guidelines limit your maximum annual dose
Speaker 1: to point zero five siverts. The average person gets point
Speaker 1: zero zero three six siverts from background radiation. Point seven
Speaker 1: five sea verts can be enough to induce radiation sickness,
Speaker 1: including nausea in a weak immune system. Three siverts is
Speaker 1: more severe, but it won't kill you. Five siverts and
Speaker 1: higher radiation will start damaging your skin so it doesn't
Speaker 1: heal properly. Your hair will fall out, scars develop under
Speaker 1: your skin, swelling and forming keloids. Now between three siverts
Speaker 1: and ten siverts gives you a fifty percent chance of
Speaker 1: dying in thirty days, and an instant dose of ten
Speaker 1: siverts that will be fatal even with medical care. The
Speaker 1: effects of radiation sickness include initial symptoms like nausea, diarrhea, headaches, fever,
Speaker 1: and a loss of consciousness. With high doses, you'll also
Speaker 1: see burns to the skin, and symptoms occur more quickly
Speaker 1: the higher the dose, but they fade over one to
Speaker 1: two days. The latent period is where there are no
Speaker 1: symptoms over several weeks, and after this period real damage
Speaker 1: is evident. Bone marrow is vulnerable and can't produce enough
Speaker 1: red or white blood cells, and this makes victims anemic
Speaker 1: and susceptible to infections. It also damages the digestive systems lining,
Speaker 1: and this allows bacteria to migrate from there into your blood,
Speaker 1: causing more infections. So you're probably wondering, well, what's the
Speaker 1: treatment available. Well, that begins with decontaminating the patient. If
Speaker 1: radioactive material is still present, Washing and special drugs like
Speaker 1: Prussian blue dye can be used, and these drugs bind
Speaker 1: radioactive particles and flush them from your body. You'll also
Speaker 1: want to evaluate your exposure with symptom checks using blood
Speaker 1: tests or a Geiger counter. You'll want antibiotics for the infections,
Speaker 1: and blood transcusions are used to compensate for damaged bone marrow.
Speaker 1: Actual marrow transplants are used in even more severe cases,
Speaker 1: and pills can reduce the symptoms of exposure. For instance,
Speaker 1: potassium iodide tablets prevent radioactive iodine from concentrating in your thyroid. However,
Speaker 1: it does not protect you from direct radiation exposure. To
Speaker 1: prevent that, well, you can start by avoiding radiation, but
Speaker 1: the CDC recommends that you stay inside your home because
Speaker 1: the walls can block some radiation and the safest room
Speaker 1: in your house is the one with the least windows.
Speaker 1: Once you're in a safe place, figure out if you've
Speaker 1: been contaminated. Ways to do this would be get out
Speaker 1: of the area, remove your outer clothes, and put these
Speaker 1: clothes in a plastic bag away from all others. Wash
Speaker 1: all your exposed body parts, and any internal contamination may
Speaker 1: need medical attention. Now you know what to do if
Speaker 1: you've been exposed to enough radiation to cause serious sickness.
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