Prime Minister Naoto Kan placed an indefinite ban on spinach and another local vegetable produced by Fukushima and neighboring prefectures Monday after samples were found to be abnormally radioactive. He also suspended Fukushima milk.
The food ban, the first since the nuclear crisis began, is certain to alarm a public already anxious about radioactive fallout from the troubled reactors at the Fukushima No. 1 power plant.
“What I want people to understand is that the amount of (contamination) will not pose a risk to public health even though the figure exceeded government standards,” Edano said.
The announcement Saturday that radiation has popped up in milk and spinach made in areas near the Fukushima No. 1 power plant has cast a shadow over food safety.
The milk, collected Thursday in the town of Kawamata, Fukushima Prefecture, contained 1,510 becquerels of iodine per kilogram, about five times the new standard.
If one were to drink the contaminated milk for an entire year, the accumulated radiation would equal that of one CT scan, based on the average amount of milk consumed by a Japanese, Edano said.
The spinach, from Ibaraki Prefecture, contained 15,020 becquerels of iodine, about seven times the standard, but only 524 becquerels of cesium, or just slightly higher than the standard of 500 becquerels per kilogram.
According to the government, eating the contaminated spinach every day would be the same as absorbing one-fifth of the radiation from a CT scan.
Michikuni Shimo, visiting professor at Fujita Health University, said people should not worry about the radiation detected in the foods. Although it is better to wash vegetables before eating them, there is no immediate need to stop consuming these foods, Shimo said.
“The most troubling thing to me is the fear that’s out of proportion to the risk,” Dr. Henry Duval Royal, a radiologist at Washington University Medical School, told the Associated Press.
It is possible to cover vegetables, fruit and animal feed with plastic sheets or tarpaulins, according to the FDA. Livestock can be moved into barns.
How much radioactive material is permitted in foods?
The World Health Organization has established limits that serve as guidelines for governments. But there are no hard and fast rules in the United States, said George H. Pauli, a retired food safety official who spent 29 years at the FDA.
“You don’t want people to slide up to the limit,” he said. “It’s treated on a case-by-case basis when there’s a problem.”
Radioactive material in food is measured in becquerels, or Bq. The limit for iodine-131 is 55 Bq per kilogram for infant food and 300 Bq per kilogram for other foods regulated by the FDA. For meat and poultry, which are regulated by the Department of Agriculture, the limit is 55 Bq per kilogram. The limit for cesium-134 and cesium-137 for all foods is 370 Bq per kilogram.
In Japan, some milk was reported to contain 1,510 Bq of iodine-131 per kilogram.
JAPAN has detected abnormal levels of radioactivity in milk and spinach in areas near a stricken nuclear plant, but the foods pose no immediate threat to humans, Government spokesman Yukio Edano says.
The contaminated milk was found in Fukushima prefecture, where the quake-damaged atomic power station is located, while the tainted spinach was discovered in neighbouring Ibaraki prefecture.
“Radiation exceeding the limit under Japanese law was detected,” he said.
The spokesman said the Government had ordered authorities in both prefectures to investigate where the products came from, how they were distributed and depending on their findings suspend sales.
Mr Edano urged consumers to remain calm, noting that even if a consumer were to drink the contaminated milk for a year, the radiation level would be the equivalent of one CT scan.
PUBLIC health fears have been raised after traces of radioactive iodine were found in Tokyo’s tap water and Japanese authorities have stopped food sales in the areas around the Fukushima nuclear plant.
Government sources said radioactive iodine had reached the water supply of the country’s capital – home to 36 million people in the greater metropolitan area – after the emergency at the quake-hit Fukushima No. 1 power plant.
Abnormal levels of radioactive iodine were also found in the water supply in the central prefectures of Gunma, Tochigi, Saitama, Chiba and Niigata, an official at Japan’s science ministry said. But the levels were far below Japan’s legal limit, added the official, who did not want to be named.
Meanwhile, Japanese authorities halted all food sales in the areas around the Fukushima plant, according to UN watchdog the International Atomic Energy Agency after high levels of radioactivity were found in milk and spinach in the region.
“Radiation exceeding the limit under Japanese law was detected,” government spokesman Yukio Edano said Saturday.
But he urged consumers to remain calm, claiming that drinking the contaminated milk for a year would only add up to the same radiation level as one CT scan.
Separate desperate battles raged Friday to cool down a spent fuel pool and three reactors at the Fukushima No. 1 nuclear plant to keep highly toxic radiation from being released into the environment.
Operator Tokyo Electric Power Co. was also trying to set up new power lines from the outside and connect them to various facilities in the troubled plant in an effort to reactivate cooling pumps and emergency core cooling systems of the troubled reactors.
If the devices are unbroken and can get electricity, they could be a significant help in Tepco’s efforts to stabilize the crippled plant.
Tepco was aiming to finish connecting the power lines to the No. 1 and 2 reactor units by the end of Friday, and to the No. 3 and No. 4 units Sunday.
Meanwhile, data released by Tepco indicated the radiation level at one sampling point at the west gate to the nuclear plant had steadily decreased to 265.0 microsieverts at 11 a.m. Friday from 351.4 microsieverts as of 12:30 a.m. Thursday.
The west gate, located within the plant’s compound, is 1.1 km west of the No. 2 reactor unit.
This could be a sign of a steady decline trend in radiation released from the plant, but it is still unclear if it was because of the use of water to cool down the spent fuel.
The provisional evaluation stands at level 5 of the International Nuclear and Radiological Event Scale for the No. 1, No. 2 and No. 3 reactors, as their cores are believed to have partially melted and radiation leaks continue, Japan’s nuclear safety agency said.
The agency set the level at 3 for the plant’s No. 4 reactor, where an overheating spent fuel pool is also posing risks, and two reactors at the power plant that were undergoing maintenance when the quake struck.
The unprecedented cooling mission, launched Thursday by the Self-Defense Forces by spraying tons of water at the plant’s No. 3 reactor building, was bolstered Friday.
SDF firetrucks shot 50 tons of water at the spent fuel pool within the No. 3 reactor building in the afternoon, along with a high-pressure water cannon truck on loan from the U.S. military, after aiming up to 60 tons of water at it and dumping water from two helicopters the day before.
“Because steam is rising, there is no doubt the water reached the storing pool,” Edano, the government’s top spokesman, said of Thursday’s operation. “But we still don’t have information on how much water” got to the target.
The spent fuel pools in the power station lost their cooling function in the wake of the March 11 killer quake and tsunami.
It is also no longer possible to monitor the water levels or temperatures in any of the pools for the four reactors.
Japanese authorities are trying to prevent total meltdown at three nuclear reactors that were damaged in Friday’s tsunami. Engineers are flooding the reactors to cool them down, then venting the radioactive steam to prevent a dangerous build-up in pressure. Thousands have been evacuated, and helicopters have detected radioactive particles 60 miles from the reactors. How can the evacuees tell if they’ve been exposed to dangerous levels of radiation?
With a blood test. Nuclear plant workers, radiologists, and rescue workers can wear badges or special rings that tell them how much radiation is in their environment. Post hoc measurement is tougher, though. Public health workers may pass a device over the patient’s clothing. The air enters an oxygen- or argon-filled chamber, and the machine detects reactions between the gas and radioactive particles. Another option is to take a swab of the patient’s nose and mouth and perform a similar experiment. If either of these methods uncover radiation exposure, doctors then draw blood. Absorption of more than 500 millisieverts of radiation can depress white blood cell levels.
At this time, it doesn’t look like anyone in Japan has taken in this much radiation. The highest reported absorption so far is just 106 msv. To put that into perspective, workers at the Chernobyl plant absorbed more than 5,000 msv, and those were the survivors. Even 500 msv is fairly benign. White blood cell counts typically rebound within a couple of days, and the patient’s increased lifetime risk of cancer is barely worth mentioning. The average American has a one-in-two chance of developing some form of cancer. One-time exposure to 500 msv raises those odds to about one-in-1.9999.
On the off chance that an unfortunate nuclear plant worker shows signs of significant radiation exposure, treatment would depend on the type of radioactive particle involved. Radioactive cesium can be treated with a chelating agent, a chemical that binds to the particle and ushers it out of the body via urine. Those who inhale a dose of radioactive iodine aren’t as lucky. While it can be treated prophylactically with potassium iodide tablets, there’s no effective remedy after the exposure. The victim has to wait for his body to process the contaminant.
Radiation Exposure Monitoring (REM) facilitates the collection and distribution of information about estimated patient radiation exposure resulting from imaging procedures.
Radiation poisoning, radiation sickness or a creeping dose, is a form of damage to organ tissue caused by excessive exposure to ionizing radiation. The term is generally used to refer toacute problems caused by a large dosage of radiation in a short period, though this also has occurred with long term exposure. The clinical name for radiation sickness is acute radiation syndrome (ARS) as described by the CDC.[1][2][3] A chronic radiation syndrome does exist but is very uncommon; this has been observed among workers in early radium source production sites and in the early days of the Soviet nuclear program. A short exposure can result in acute radiation syndrome; chronic radiation syndrome requires a prolonged high level of exposure.
Radiation exposure can also increase the probability of developing some other diseases, mainlycancer, tumours, and genetic damage. These are referred to as the stochastic effects of radiation, and are not included in the term radiation sickness.
The use of radionuclides in science and industry is strictly regulated in most countries. In the event of an accidental or deliberate release of radioactive material, either evacuation or sheltering in place are the recommended measures. For information on the effects of lower doses of radiation, see the article on radiation orders of magnitude.
Exposure levels
A gray (Gy) is a unit of radiation dose absorbed by matter. To gauge biological effects the dose is multiplied by a ‘quality factor’ which is dependent on the type of ionising radiation. Such measurement of biological effect is called “dose equivalent” and is measured in sievert (Sv). For electron and photon radiation (e.g. gamma), 1 Gy = 1 Sv.
The corresponding non-SI units are the rad (radiation absorbed dose; 1 rad = 0.01 Gy), and rem (roentgen equivalent mammal/man;[8]1 rem=0.01 Sv).
Annual limit on intake (ALI) is the derived limit for the amount of radioactive material taken into the body of an adult worker by inhalation or ingestion in a year. ALI is the intake of a given radionuclide in a year that would result in:
a committed effective dose equivalent of 0.05 Sv (5 rems) for a “reference human body”, or
a committed dose equivalent of 0.5 Sv (50 rems) to any individual organ or tissue,
Radiation sickness is generally associated with acute (a single large) exposure.[4][5] Nausea and vomiting are usually the main symptoms.[5]The amount of time between exposure to radiation and the onset of the initial symptoms may be an indicator of how much radiation was absorbed,[5] as symptoms appear sooner with higher doses of exposure.[6] The symptoms of radiation sickness become more serious (and the chance of survival decreases) as the dosage of radiation increases. A few symptom-free days may pass between the appearance of the initial symptoms and the onset of symptoms of more severe illness associated with higher doses of radiation. Nausea and vomiting generally occur within 24–48 hours after exposure to mild (1–2 Sv) doses of radiation. Radiation damage to the intestinal tract lining will cause nausea, bloody vomiting and diarrhea. This occurs when the victim’s exposure is 200 rems (1 Sv = 100 rems) or more. The radiation will begin to destroy the cells in the body that divide rapidly, including blood, GI tract, reproductive and hair cells, and harm the DNA and RNA of surviving cells. A direct quantitative relationship exists between the degree of the neutropenia that develops after exposure to radiation and the increased risk of developing systemic infection (sepsis). Headache, fatigue, and weakness are also seen with mild exposure.[7] Moderate (2–3.5 Sv of radiation) exposure is associated with nausea and vomiting beginning within 12–24 hours after exposure.[7] In addition to the symptoms of mild exposure, fever, hair loss, infections, bloody vomit and stools, and poor wound healing are seen with moderate exposure. Nausea and vomiting occur in less than 1 hour after exposure to severe (3.5–5.5 Sv) doses of radiation, followed by diarrhea and high fever in addition to the symptoms of lower levels of exposure. Very severe (5.5–8 Sv of radiation[citation needed]) exposure is followed by the onset of nausea and vomiting in less than 30 minutes followed by the appearance of dizziness, disorientation, and low blood pressure in addition to the symptoms of lower levels of exposure. Severe exposure is fatal about 50% of the time. Severe sepsis is the cause of death in most cases. See criticality accident for a number of incidents in which humans have been accidentally exposed to such levels of radiation.
Longer term exposure to radiation, at doses less than that which produces serious radiation sickness, can induce cancer as cell-cycle genes are mutated. The probability cancer will develop is a function of radiation dose. In radiation-induced cancer the disease, the speed at which the condition advances, the prognosis, the degree of pain, and every other feature of the disease are not functions of the radiation dose to which the person is exposed.
Since tumors grow by abnormally rapid cell division, the ability of radiation to disturb cell division is also used to treat cancer (seeradiotherapy), and low levels of ionizing radiation have been claimed to lower one’s risk of cancer (see hormesis).
Organisms causing sepsis
The systemic infections can be endogenous originating from the oral and gastrointestinal bacterial flora, and exogenous originating from a breached skin and environment following trauma.
The organisms causing endogenous infections are generally Gram negative bacilli such as Enterobacteriacae (i.e. Escherichia coli, Klebsiella pneumoniae, Proteus spp.), Pseudomonas aeruginosa, and Enterococcus spp. (of gastrointestinal origin) and Streptococcus spp. (of oral cavity source).
Exposure to higher doses of radiation is often associated with anaerobic infections due to Gram negative bacilli and gram positive cocci. Fungal infections can also emerge in those who fail antimicrobials and are still febrile for over 7-10 days.
Exogenous infections can be caused by organisms that colonize the skin such as Staphylococcus aureus or Streptococcus spp. and organisms that are acquired from the environment such as Pseudomonas spp.
During a routine test, the plant’s safety systems were turned off to prevent any interruptions of power to the reactor. The reactor was supposed to be powered down to 25 percent of capacity, but this is when the problems began. The reactor’s power fell to less than one percent, and so the power had to be slowly increased to 25 percent. Just a few seconds after facility operators began the test, however, the power surged unexpectedly and the reactor’s emergency shutdown failed. What followed was a full-blown nuclear meltdown.
The reactor’s fuel elements ruptured and there was a violent explosion. The fuel rods melted after reaching a temperature over 3,600 degrees Fahrenheit. The graphite covering the reactor then ignited and burned for over a week, spewing huge amounts of radiation into the environment.
About 200,000 people had to be permanently relocated after the disaster. IAEA reported in 2005 that 56 deaths could be linked directly to the accident. Forty-seven of those were plant workers and nine were children who died of thyroid cancer. The report went on to estimate that up to 4,000 people may die from long-term diseases related to the accident. Those numbers are a subject of debate, however, as the Soviet Union did much to cover up the extent of the damage. The World Health Organization reported the actual number of deaths related to Chernobyl was about 9,000.
Kyshtym, Soviet Union (now Russia)
Sept. 29, 1957
INES Rating: 6
The Soviet Union was also home to the second-most disastrous nuclear accident, at the Mayak Nuclear Power Plant near the city of Kyshtym. IAEA classified the event as a Level 6 Disaster, which is a “serious accident.”
Soviet scientists were frantically trying to catch up to the Americans after World War II when they began construction of the Mayak nuclear facility. Soviet nuclear knowledge had many holes, so it was impossible to know whether some decisions made in the construction were safe. As it turned out, many of those decisions seriously compromised the plant’s facility.
Initially, the plant’s operators simply dumped the nuclear waste into a nearby river, before a storage facility for that waste opened in 1953. The storage facility began to overheat, and a cooler was soon added, but it was poorly constructed.
In September 1957, the cooling system in a tank containing about 70 tons of radioactive waste failed, and the temperature started to rise. This caused a non-nuclear explosion of dried waste. There were no immediate casualties as a result of the explosion, but the IAEA found there had been a significant release of radioactive material into the environment. The radioactive cloud spread out for hundreds of miles to the northeast.
The Soviet government released little information about the accident, but was forced to evacuate 10,000 people in the affected area after reports surfaced of people’s skin literally falling off. The radiation is estimated to have directly caused the deaths of 200 people due to cancer.
Windscale Fire, Great Britain
Oct. 10, 1957
INES Rating: 5
Image credit: Getty Images
Great Britain’s first foray into nuclear energy had been successful for several years before the Windscale fire occurred in 1957. Operators noticed that the reactor’s temperature was steadily rising when it should have been decreasing. They originally suspected the equipment was malfunctioning, so two plant workers went to inspect the reactor. When they reached the reactor, they discovered it was engulfed in flames.
At first, they did not use water, because plant operators were worried the flames were so hot the water would break down instantly, and the hydrogen in the water would cause an explosion. But their other methods to put out the fire did not work, and so they turned on the hoses. The water was able to put the fire out without an explosion.
It is estimated that 200 people in Britain developed cancer because of Windscale, half of them fatal. The exact number of fatalities is hard to come by because the British government attempted to cover up how serious the fire had been. Prime Minister Harold Macmillan worried the incident would embarrass the British government and erode public support for nuclear projects. It’s also difficult to put an exact number on the deaths because radiation from Windscale spread hundreds of miles across northern Europe.
The United States’ most disastrous nuclear accident took place at the Three Mile Island Plant near Harrisburg, Penn., the state’s capitol.
It all began with a simple plumbing break down. A small valve opened to relieve pressure in the reactor, but it malfunctioned and failed to close. This caused cooling water to drain, and the core began to overheat. The machines monitoring conditions inside the nuclear core provided false information, so plant operators shut down the very emergency water that would have cooled the nuclear core and solved the problem. The core began to overheat, and reached 4,300 degrees Fahrenheit. The water nearly reached the fuel rods, which would have caused a full meltdown of the core. But the nuclear plant’s designers were finally able to reach the plant operators several hours later to instruct them to turn the water back on, and conditions stabilized.
“Not only were there issues with training of operators, but management for both the plant and NRC did not know how to approach this kind of emergency and to communicate with the public,” said Burnell.
The NRC determined that no one had died of causes related to the incident at Three Mile Island, but found there might be one excessive cancer death over a 30-year period as a result of radiation. Only one person outside of the nuclear plant was found to have any radiation in his system after the incident.
Three Mile Island had a profound impact on the public’s attitude toward nuclear energy. In the 30 years since Three Mile Island, not a single nuclear power plant has been approved for development.
Tokaimura, Japan
Sept. 30, 1999
INES Rating: 4
Japan’s most disastrous nuclear accident took place over a decade ago just outside Tokyo.
A batch of highly-enriched uranium was prepared for a nuclear reactor that had not been used in more than three years. The operators had not been trained in how to handle uranium that was so highly enriched. They put far more uranium into the solution in a precipitation tank than is allowed. The tank was not designed for this type of uranium.
Only when the tank was drained of the solution could the critical reaction be stopped, but by then, it was too late for two of the three operators working with the uranium, as they died of radiation.
Less than a hundred workers and people who lived nearby were hospitalized for exposure to radiation, and 161 people who lived within 1,000 feet of the plant were evacuated, according to the World Nuclear Association.
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