Nuclear emergency: What you need to know

(RNN) - Japanese officials raised the threat level from the nuclear crisis at their Fukushima Gaiichi power plant from a Level 4 to Level 5 on a seven-level scale Friday after repeated attempts to cool three of its reactors have failed.

For many, the announcement came as confirmation of what they had suspected since the first explosion last Saturday – that the crisis is much worse than Japanese officials have let on. The fear surrounding the nuclear accidents, brought on by the tsunami that resulted from the 9.0 earthquake that struck the island last week, has spread from East Asia to the west.

Supplies of potassium iodide, a drug used to block the effects of radiation on the thyroid, have sold out, and the manufacturer of the product is struggling to keep up with demand. On Thursday, President Barack Obama tried to reassure worried Americans that Japan's crisis won't become America's crisis.

"We are bringing all available resources to bear to closely monitor the situation and to protect American citizens who might be in harm's way," Obama said. "I want to be very clear: We do not expect harmful levels of radiation to reach the United States, whether it is the West Coast, Hawaii, Alaska or U.S territories in the Pacific. That is the judgment of the Nuclear Regulatory Commission and many other experts."

According to forecasters, a plume of radiation from Japan's reactors is expected to reach the West Coast on Friday, however government officials say it will not be a threat to human health.

Friday, deputy U.S. Energy Secretary Daniel Poneman told CBS's "The Early Show" that the U.S. is doing all it can to monitor the situation and quell the panic.

"We've done everything we can from the Department of Energy to provide the monitoring, the crisis management support that we can and rest assured this is a close friend and a strong ally and we're going to be there for the Japanese people," Poneman said. "We expect no harmful levels of radiation to reach the West Coast, to reach Hawaii, Alaska, or any of the Pacific territories."

In the wake of Japan's triple tragedies – earthquake, tsunami, and nuclear emergencies – fear is growing by the day. Here is a brief rundown of what you need to know about Japan's nuclear crisis:

What is acute radiation syndrome?

ARS is radiation sickness, and is caused by exposure to high levels of radiation over a very short period of time. Symptoms include nausea, vomiting and diarrhea, and will start within minutes to days of first exposure.  After the initial sickness, the person becomes well, then sick again with more serious symptoms, including loss of appetite, fatigue, fever, nausea, vomiting, diarrhea and possibly seizure and coma. It may include skin damage (itching and redness) and hair loss.

Most people do not recover from ARS and will die within several months of exposure.

What is Potassium Iodide?

If radioactive material enters the air and is breathed by the lungs, the radioactive isotopes are quickly absorbed by the thyroid. Potassium iodide (Chemical symbol: KI) blocks radioactive iodine from being taken into the thyroid gland and prevents injury. It cannot protect parts of the body other than the thyroid. It also may not give a person 100 percent protection against radioactive iodine. Taking the wrong dose can cause severe injury or death.

The Centers for Disease Control and Prevention does not recommend people in the United States take potassium iodide or iodide supplements in response to the nuclear power plant explosions in Japan.

Is potassium iodide available over the counter?

Yes. Potassium iodide is available to individual members of the public.

Is it in short supply?

The Food and Drug Administration is aware of an "acute demand" for potassium iodide and is working with suppliers to facilitate the greater demand. Several government organizations have their own emergency supply, including the CDC and the Department of Defense. The FDA says it is not aware of any request from the Japanese for potassium iodide. The FDA is alerting anyone thinking about purchasing potassium iodide over the internet that some companies make false claims about their product's ability to prevent or treat the effects of radiation. Specifically, avoid products that are not FDA approved.

What is Prussian blue, and should I take it?

According to the CDC, Prussian blue is another treatment that can remove certain radioactive materials, such as cesium and thallium, from the human body.  Prussian blue traps the material in the intestines and keeps them from being absorbed in the body. It should only be taken under the guidance of a doctor. It is available only by prescription.

The CDC – or any other body – is not recommending treatment by Prussian blue at this time.

"The Centers for Disease Control and Prevention and other health experts do not recommend people in the united states to take precautionary measures beyond staying informed," Obama said.

Who is monitoring the U.S.'s exposure to radiation?

The Environmental Protection Agency (EPA) has a nationwide monitoring system comprising 100 air monitors in 49 states that covers about 70 percent of the U.S. It also has 40 deployable monitors that can take readings anywhere in the country. It has 40 deployable radiation monitors. If results indicate abnormal radiation levels, EPA staff is immediately notified and verifies the data before posting the information to its Central Data Exchange website.

According to its website, the EPA says it does not "expect to see radiation levels at harmful levels reaching the U.S. from damaged nuclear power plants."

What is the risk of radiation-related health problems in Japan?

The Japanese government has requested people living within 20 km of the Fukushima Daiichi nuclear power plant to evacuate, and those between 20 km and 30 km to say indoors. However, the U.S. has recommended an 80-km radius evacuation zone. These ranges could change if conditions change. Radiation-related health problems depend on exposure. Rescue workers and first responders may be at highest risk for radiation sickness.

Is it safe to eat food imported from Japan?

According to the World Health Organization, Japan is not a major exporter of food, and given the disasters, it would be "unlikely" that food production or harvesting is taking place in the evacuated areas.

However, the Los Angeles Times reported Thursday that the Food and Drug Administration (FDA) is examining food products that originated from Japan or passed through the country. By early next week, ships that left Japanese ports around the time of the first explosions should begin reaching American ports. It typically takes eight days for shipments to arrive in the U.S. from Japan.

What types of products come from Japan?

Less than 4 percent of foods imported into the U.S. come from Japan, according to the FDA. Imports from Japan include human and animal foods, medical devices and radiation emitting products, cosmetics, animal and human drugs and biologics, dietary supplements and animal feed. The most common food products imported include seafood, snack foods and processed fruits and vegetables.

What about airplanes arriving from Japan? Are they radioactive?

Customs and Border Protection agents have stressed that dangerous radiation levels have not been detected at any U.S. airport. However, USA Today reported Thursday that low levels of radiation have been detected in cargo at several U.S. airports: Chicago O'Hare, Dallas/Fort Worth and Seattle/Tacoma.

What is being done now to bring the reactors under control?

The emergency level was raised from 4 to 5 after nuclear officials realized that 3 percent of the fuel in the reactors had been damaged and are probably at least partially melted down, releasing damaging radioactivity into the air.

For a second day, military fire trucks are being used to spray the damaged reactors. At least one U.S. vehicle and six Japanese vehicles were used and allowed nuclear workers to stay a safe distance away from the damaged reactors.

The Associated Press reported Friday that the operator of the plant, Tokyo Electric Power Co., missed a deadline late Thursday to have new power lines laid to bring the cooling system back online, but they hoped to have the task completed Friday.  However, it is unknown if the cooling system is still intact and operational, or whether it would bring the emergency under control.

Sources: Centers for Disease Control, World Health Organization, Nuclear Regulatory Commission, Food and Drug Administration, Environmental Protection Agency.

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