WHO issues guidelines on radiation exposure - Hướng dẫn của Tổ chức Y tế thế giới về phơi nhiễm phóng xạ

Logistics Spc. 2nd Class Robert Bannister carries a shovelful of sediment as he and his unit cleans up behind a damaged building in Hachinohe, Japan. About 17,000 U.S. military personnel are involved in relief operations in the country. GENEVA (Reuters) - In the wake of Japan's nuclear crisis, the World Health Organization (WHO) issued fresh guidelines on how to minimize exposure to radiation that can cause cancers, especially in children and young adults. The United Nations agency said measures taken by Japan so far meet its public health recommendations, including evacuating people within 20 km of the crippled Fukushima nuclear power plant and asking those within 30 km to stay indoors. There was no indication of food safety risks due to imports of food products from Japan. It was also unlikely food production or harvesting in the affected area was taking place, but it said crops and livestock in the area should be protected. Following is a list of the main WHO recommendations: * The main radionuclides released in a nuclear power plant accident are radioactive cesium and radioactive iodine. "Members of the public may be exposed directly to such radionuclides in the suspended air or if food and drink are contaminated by such materials," the WHO said. * If radioactive iodine is breathed in or swallowed, it will concentrate in the thyroid gland and increase the risk of thyroid cancer. This risk can be lowered by taking potassium iodide pills which saturate the thyroid gland and help prevent the uptake of the radioactive material. "When given before or shortly after exposure, this step can reduce the risk of cancer in the long term," it said. National authorities are best placed to determine if it is warranted to take the tablets. * If a dose of radiation exceeds a certain threshold level, then it can produce skin redness, hair loss, radiation burns and acute radiation syndrome. Due to their work, rescuers and nuclear power plant workers may be exposed to higher radiation doses than the general population. * Exposure to radiation can increase the risk of cancer. Among the survivors in Japan of U.S. atomic bombs dropped in August 1945, the risk of leukemia increased a few years after radiation exposure, while the risks of other cancers increased more than 10 years after the exposure. * The risk of thyroid cancer following radiation exposure is higher in children and young adults. * If warranted, steps such as restricting the consumption of vegetables and dairy products produced in the vicinity of the power plant can also reduce exposure. * "If you are coming indoors after radiation exposure, undress in the doorway to avoid further contamination in your home or shelter. Remove clothing and shoes and place them in a plastic bag. Seal the bag and place it in a safe location, away from living areas, children, and pets," it said. * "Shower or bathe with warm, not scalding hot, water and soap. Notify authorities that you may have contaminated clothing and personal belongings to be handled appropriately and disposed of according to accepted national procedures," the WHO said. * "If you are advised to stay indoors, you should find the safest room in your house or office building that has no windows or doors. Ventilation systems, such as heating and cooling systems, should be shut down," the agency said. * Foods can be contaminated with radioactive materials as a result of a nuclear or radiological emergency. "The surface of foods like fruits and vegetables or animal feed can become radioactive by deposit of radioactive materials falling on it from the air or through rain water." * Over time, radioactivity can also build up within food, as radionuclides are transferred through soil into crops or animals or into rivers, lakes and the sea where fish and shellfish could take up the radionuclides. * "Radioactivity cannot contaminate food that is packaged; for example, tinned or plastic-wrapped food is protected from radioactivity as long as the food is sealed," the WHO said. * In the early stages of an emergency, and if it is safe to do so, vegetables and animal fodder can be protected with plastic sheets or tarpaulins. "Bring livestock in from pasture; move animals into a shed or barn. Harvest any ripe crops and place under cover," it said. * Avoid consumption of locally produced milk or vegetables, avoid slaughtering animals and avoid fishing, hunting or gathering mushrooms or other forest foods.

Japan nuclear accident poses crisis for worker safety - Sự cố hạt nhân Nhật bản đe dọa an toàn tính mạng công nhân

Workers at the damaged Fukushima Daiichi nuclear plant could rapidly reach their annual radiation exposure limit and may have to be rotated out soon.

An aerial view of the damaged Reactor No. 4 at the Fukushima Daiichi nuclear power facility. (Reuters)

Bursts of radiation being released at the stricken Fukushima nuclear plant could mean workers there will have to be quickly rotated out, and some could rapidly reach their annual exposure limit, complicating efforts to contain Japan's continuing nuclear crisis.

"Those are pretty brave people," David Brenner, the director of the Center for Radiological Research at Columbia University Medical Center, said of the workers. "There are going to be some martyrs among them."

Disaster officials could face a grim choice: Scale back their containment efforts or allow workers to face radiation levels that could significantly increase their risk of cancer.
Reports on Thursday indicated that at times radiation was intense enough to exceed even Japan's newly raised annual limit in as little as an hour.

The new limit — 250 millisieverts — is five times the allowable exposure in U.S. nuclear plants and 125 times what workers typically receive each year.

That level of exposure raises the chances that workers will eventually die of cancer by 1 percentage point, according to John Boice, a cancer epidemiologist at Vanderbilt University and radiation safety expert.

Considering the scope of the disaster — and the fact that at least 20% of people already die of cancer — many workers may be willing to accept the danger. The situation becomes more complicated at higher doses, because radiation risk is cumulative. In other words, the risk of dying of cancer rises an extra percentage point with each additional 250 millisieverts.

It is not clear for how long the government will abide by its new limit.

There were conflicting reports about the amount of radiation the workers may have received so far. It also was not clear if the releases were planned and whether the workers were sheltered at the time.

At one point on Thursday, a level of 400 millisieverts per hour was recorded at the plant. That reading was an instantaneous measurement, and it was not clear how long that emission rate was sustained. But at that rate, a fully exposed worker would have to leave in 37 minutes, 30 seconds and not come back for a year to avoid exceeding the limit.

The Japanese government has tried to protect workers by keeping as few people on-site as possible, monitoring how much radiation they receive and limiting helicopter missions to drop water on the plant. Special clothing and respirators provide some protection from the damaging emissions.

"The main danger is gamma radiation," said Elmer Lewis, a nuclear plant safety expert at Northwestern University in Evanston, Ill. "Gamma can penetrate your body no matter what you're wearing out there. It's like a high-powered X-ray."

The plant workers are trained to react to crisis through simulated disasters, Lewis said.

But, he said, "there's really no way to anticipate what we're seeing here. They're professionals who are doing the best with what they have."

The most acute danger would come from a sudden release of radiation from which workers could not escape — an explosion, for example. That could cause radiation sickness, a devastating illness that is often fatal.

In the 1986 Chernobyl disaster in Ukraine, then part of the Soviet Union, the worst nuclear plant accident in history, workers who battled a weeklong fire were exposed to radiation at levels thousands of times higher than the Japanese yearly limit.

At first, people exposed to that much radiation might look normal. In a week, things change drastically.

"People's hair starts to fall out and the burns appear and the bone marrow damage starts," said Dr. Robert Peter Gale, a hematologist who flew to Moscow days after the accident to try to save workers airlifted there. He is scheduled to fly to Japan on Saturday to help with the Fukushima relief efforts.

Gale treated Chernobyl exposure victims with antibiotics and experimental hormones. In 13 cases, he performed bone marrow transplants in an attempt to revive their immune systems.

Of 600 workers present when the Chernobyl accident occurred, 134 developed radiation sickness, and 28 of those died within four months, according to the United Nations. Many of the rest have continued to battle health problems. Several developed cataracts.

The number of workers at the damaged Fukushima Daiichi plant during the crisis has varied from about 50 to 180, except for an hour or two when all workers had withdrawn.

Still, it is difficult to compare the accidents.

Some firefighters sent to the burning Chernobyl reactor later said they were not warned about the radiation danger, and many workers lacked protective suits and breathing devices. Soviet officials sent helicopters into the clouds of radioactive smoke to help douse the fire.

The actions of the power plant workers in Japan have already been described as heroic, and examples of heroism are common in such situations, said Dr. Fred Mettler, a University of New Mexico radiologist and advisor to the U.N. on radiation safety.

At one point during the Chernobyl disaster, he said, workers were conferring about how much water was in one reactor pool. No one knew the answer and their instruments couldn't tell them, he said. "An Armenian engineer slipped out and came back in 30 minutes. He said, 'There's 3 feet of water,' " Mettler said. "He did that on his own."

The engineer died soon after of acute radiation poisoning.

"Its always hard to tell what people are going to do," he said. "Workers have done remarkable things, some things you wouldn't expect."

Nuclear plant workers in the United States expressed a camaraderie with their Japanese counterparts, even as they puzzled over the response to the catastrophe. "I have a lot of empathy for the Japanese people, for those workers," said Charlie Arnone, 51, general manager of plant operations at the Waterford 3 facility on the Mississippi River in Killona, La. "They're clearly very dedicated folks."

Arnone, who has worked with nuclear energy since 1977, said he and other workers train according to federal Severe Accident Mitigation Guidelines, scenarios specific to each plant. They review what could happen if, for instance, they can't maintain the water level in a spent fuel pool.

"We might hook up things, basically fire nozzles that automatically spray. Then if that doesn't work, you can open up and try air cooling," Arnone said. "We just have different guidelines and tools. My understanding is the Japanese don't have that. We have all this equipment staged. We have a generator already set up, and we can pull water out of the river if we have to, to keep the core cool, the spent fuel cool."

Experts are focusing their concern on nuclear workers because the general population's exposure to radiation around the Fukushima Daiichi plant has so far been minimal.

The government quickly evacuated a 12-mile zone around the plant. Readings of radiation outside that area have remained low.

The utility that operates the plant, Tokyo Electric Power Co., has released gases laden with radioactive substances in small bursts to prevent the buildup of pressure inside the containment buildings. For now, the winds have cooperated in blowing much of the material out to the Pacific Ocean, where scientists say it settles in the water and is diluted into concentrations that pose little danger.

Even in Chernobyl, nobody in the general population suffered radiation sickness. The U.N. says that 6,500 cases of thyroid cancer can be attributed to the disaster, but because the cases were closely monitored and treated, only a few were fatal.

Those occurred mainly because people were not warned to stop drinking milk — the main way that dangerous quantities of radioactive iodine enter the body. The isotopes land on the grass, which is then eaten by cows, turning their milk radioactive.

"All they had to say was 'don't drink the milk,' " Boice said.

"In Japan, radioactive iodines are not going to be that big a deal," he said. "They won't let the milk into the food supply."

Photos: Crisis continues in Japan

alan.zarembo@latimes.com

Menthol's cool feeling comes at a price - Came giác mát của thuốc lá có Menthol hại nhiều hơn lợi

Menthol seems fresh, cool, natural -- and that's what makes it dangerous. Added to the tobacco in cigarettes, menthol makes the biologically nightmarish act of inhaling smoke feel much better than it should.	Tinh dầu bạc hà có vẻ tươi, mát mẻ, tự nhiên - và đó chính là điều làm cho nó nguy hiểm. Khi được tẩm vào sợi thuốc trong trong những điếu thuốc lá, tinh dầu bạc hà làm cho người hút thấy những tác hại về mặt sinh học của việc hít khói thuốc lá trở nên nhẹ nhàng hơn nhiều so với thực tế
Just ask the panel charged with advising the Food and Drug Administration on the additive.	Chỉ cần hỏi ban phụ trách tư vấn cho Cục Quản lý Thực phẩm và Dược phẩm (FDA ) về chất phụ gia sẽ rõ.
The panel has delivered to the FDA a lengthy report about the public health effect of menthol in sticks of smokable tobacco.	Ban phụ trách này đã gởi cho FDA một báo cáo rất dài về tác hại đối với sức khỏe của công chúng của tinh dầu bạc hà những điếu thuốc lá có khói.
The report poses the following questions: -- "Does menthol have cooling and/or anesthetic properties that moderate the harshness of cigarette smoke?" -- "Does menthol make low-tar, low-nicotine cigarettes more acceptable to smokers?" -- "Does menthol have an effect on nicotine or nicotine-derived nitrosamine metabolism?" -- "Is it biologically plausible that menthol increases the addictiveness of cigarette smoking?"	Bản báo cáo đặt ra các câu hỏi sau: - "Liệu tinh dầu bạc hà có tính chất làm mát và/hoặc gây tê, mà làm điều hòa mức độ mùi gay gắt của khói thuốc lá hay không?" - "Tinh dầu bạc hà có thể làm các loại thuốc lá có mức hắc ín thấp và nicotine thấp chấp nhận được đối với người hút thuốc hay không?" - “Tinh dầu bạc hà có ảnh hưởng đến chuyển hóa nitrosamine (một dẫn xuất từ nicotine) hay không?" - "Có đúng rằng tinh dầu bạc hà về mặt sinh học có vẻ như làm tăng tính gây nghiện của hút thuốc lá hay không ?"
Yes, are the answers, in long-winded but enlightening form, to each one. And that's simply the report's look at individual smokers. At that point, the authors were just getting warmed up.	Đúng thế, đó là câu trả lời, với hình thức dài dòng, nhưng sáng tỏ, cho mỗi một câu hỏi trên. Và đó chỉ đơn giản là báo cáo xem xét những người hút thuốc cá nhân. Vào thời điểm này, các tác giả chỉ mới bắt đầu nghiên cứu.
There's also data showing menthol cigarette use is common among women, minorities, the unemployed, poor people and, most alarming, adolescents. Young people, it seems, like menthol quite a bit. And who can blame them? New smokers need all the help they can get.	Ngoài ra còn có dữ liệu cho thấy sử dụng thuốc lá có tinh dầu bạc hà rất phổ biến ở phụ nữ, các nhóm thiểu số, người nghèo và thất nghiệp, đáng báo động nhất là vị thành niên. Những người trẻ có vẻ cũng khá thích tinh dầu bạc hà. Và ai có thể trách họ? những người mới tập hút thuốc cần tất cả mọi sự giúp đỡ mà họ có thể nhận được.
There's more in the report of course, so very much more. But let's focus on the big picture.	Báo cáo này còn có nhiều nội dung khác nữa, rất nhiều. Nhưng chúng ta hãy tập trung vào những vấn đề lớn.
The report asks: "Does the availability of menthol cigarettes increase the prevalence of smoking in the population, beyond the anticipated prevalence if such cigarettes were not available? In subgroups within the population?"	Báo cáo hỏi: "Liệu sự sẵn có của thuốc lá có tinh dầu bạc hà có làm tăng tỷ lệ hút thuốc lá trong dân số hay không, có vượt quá tỷ lệ dự đoán nếu những điếu thuốc lá này không có sẵn hay không? Cả ở các nhóm nhỏ trong dân cư?"
And the report answers: "The evidence is sufficient to conclude that it is more likely than not that the availability of menthol cigarettes increases the likelihood of experimentation and regular smoking beyond the anticipated prevalence if such cigarettes were not available, in the general population and particularly in African Americans."	Và báo cáo đã trả lời: "Bằng chứng là đủ để kết luận rằng nó có nhiều khả năng sự có sẵn thuốc lá bạc hà làm tăng khả năng thử hút thuốc và hút thuốc thường xuyên vượt quá tỷ lệ dự đoán nếu không có sẵn thuốc lá bạc hà, trong quần thể nói chung và đặc biệt ở những người Mỹ gốc Phi. "
Thus does the Tobacco Products Scientific Advisory Committee make its way toward its recommendation to the FDA: "Removal of menthol cigarettes from the marketplace would benefit public health in the United States."	Do đó liệu Ủy ban tư vấn khoa học về sản phẩm thuốc lá có tiến hành kiến nghị với FDA: "Loại bỏ thuốc lá tinh dầu bạc hà trên thị trường sẽ có lợi cho sức khỏe cộng đồng tại Hoa Kỳ."
Friday's delivery of this recommendation puts the ball in the Food and Drug Administration's court. The agency can't say it lacks facts.	Những khuyến cáo của bản báo cáo hôm thứ sáu là đưa những dữ liệu này cho Hội đồng quản lý Dược và thực phẩm. Các cơ quan này không thể nói nó thiếu thực tế.
Translated by	tndinhdat@yahoo.com.vn

How do cell phones affect young brains? Điện thoại di động ảnh hưởng não thế nào?

Cell phone safety warnings are generally designed for a large man with

a big head who talks less than half an hour a day.

The average toddler's head, however, weighs about half as much and is

far more susceptible to the microwave radiation the phone emits, said

environmental health expert Devra Lee Davis, founder of the

Environmental Health Trust, which campaigns for safer cell phone use.

As the debate over cell phones and cancer continues to rage, concern

is growing over the effects of the phones — as well as devices such as

the iPad — on children.

A recent study published in the Journal of the American Medical

Association found that pressing a cell phone to the ear for 50 minutes

altered the brain activity in 47 adult volunteers.

The study doesn't answer the million dollar question: whether the

change in brain activity causes any harm.

The wireless industry group says no research has proven cell phones to

be dangerous.

The National Cancer Institute, meanwhile, says there is no consistent

link between cell phones and cancer.

But the NCI also notes that there's currently no data on cell phone

use and risk of cancer in children and that children may be at a

greater risk because their nervous systems are still developing at the

time of exposure.

Meanwhile, cell phone use by children and adolescents is increasingly

rapidly.

Experts worry that children's brains, encased in a thinner skull, may

be more vulnerable to the effects of the radiation emitted by the

phones.

Dr. Nora Volkow, the lead author of the JAMA study, said modeling

studies have shown that a child's brain would absorb more radiation

than those of adults. But Volkow said she's unaware of studies that

have looked at the different developmental effects.

Some studies have suggested that the radiation can cross or affect the

entire brain of children, who are still developing, versus a

particular area in adults," said Dr. Stephanie Wagner, co-medical

director of the neuro-oncology program at Indiana University Health

and the IU Simon Cancer Center in Indianapolis.

But studies looking at the effects of electromagnetic radiation in

children and the risk of epilepsy and behavioral problems such as

attention deficit disorder and aggressive behavior showed conflicting

results, Wagner said.

Still, why take a chance, Volkow said.

She suggested that parents "teach their children to use their cell

phones with a wired earphone and/or use the speakerphone mode and to

avoid putting their cell phones directly on their ear."

jdeardorff@tribune.com



Concerned?



If so, try these tips, starting with the most drastic, to limit

exposure.

•Avoid white noise baby apps. Some children are falling asleep to

white noise played from iPhones or Blackberries under their pillows.

But the phones must stay on for the app to work. "A cell phone is a

two-way microwave radio," said Davis. "That means infants stay asleep

with their brains being radiated by the phones all night long."

•Don't let toddlers or young children use cell phones. Teenagers

should limit use to head sets or texting to keep the antenna away from

the brain, said Wagner. Or shift the phone between ears.

•Review SAR levels. The Specific Absorption Rate (SAR) is a measure of

the amount of radio frequency (RF) energy absorbed by the body when

using the handset. Before you buy your child a phone, search the

government's cell phone database (fcc.gov/cgb/sar).

•Follow the "one-inch" rule. Most cell phone manuals advise holding

the phone "at least one inch" away from the head.

•Don't carry a cell phone on your body. Place the phone inside a bag

or some type of holster; this will help block the radiation from

reaching the body.

•Limit phone use when the signal is weak. The radiation increases as

the device searches for a signal.

Worries outweigh radiation threats in U.S. Lo lắng nhiều hơn so với đe dọa phóng xạ ở Mỹ

All that worrying might cause more harm than the radiation from the Japan nuclear accident, experts say. A look at some common concerns.

In Japan, a baby is checked for radiation exposure before entering an evacuation center in Fukushima. Meanwhile, Californians are worrying that radiation plumes will find their way to American shores. (AP Photo / Kyodo News)

With reports that a radiation plume from the Fukushima Daiichi nuclear plant could reach Southern California as soon as Friday, worried citizens have been hoarding potassium iodide pills, wondering if it's OK to go outside and otherwise fretting over an invisible, and somewhat unpredictable, threat.

But all that worrying might cause more harm than the radiation itself, experts say. Here are some answers to common concerns.

How much radiation do scientists think will arrive here?
No one knows yet — but probably not a whole lot. It's unclear what's happening at the Japanese power plant, and whatever radiation escapes has to travel thousands of miles to reach U.S. shores. Over that distance, it will be greatly diluted, if it gets here at all.

Photos: In Japan, life amid crisis

In fact, the winds have been shifting, often blowing westward, back toward Japan, rather than toward the U.S., California officials said in a news conference Thursday. "We are not in Japan," said Dr. Jonathan Fielding, director of Public Health for Los Angeles County. "We are not within 10 miles of the reactor. We are 5,000 miles away — and we know a lot about dispersal patterns over that distance."

How much risk will any radiation that reaches here pose?

Not much. Gregory Jaczko, chairman of the Nuclear Regulatory Commission, an independent agency that regulates U.S. commercial nuclear power plants, told reporters Thursday that the basic science involved suggested that "there can't be any risk or harm to anyone here in the United States, or Hawaii, or any of the other [U.S.] territories."

Dr. Kei Iwamoto, of the faculty of the Division of Molecular and Cellular Oncology at UCLA, told The Times that he believed the amount of radiation from Japan that a person in California might be exposed to will be very low — perhaps around one microsievert.

To put that in perspective, people get some amount of radiation every day. Humans are exposed, on average, to 3,000 microsieverts of natural background radiation per year, according to the Centers for Disease Control and Prevention. One dental X-ray would add 40-150 µSv to that baseline. A CT scan of the abdomen, according to the Food and Drug Administration, would tack on another 8,000 µSv — more than 2 1/2 years of background radiation.

Did radiation reach here from Chernobyl? What happened then?

Yes, a tiny amount did reach the United States. But its health effects were miniscule, if they existed. "The radiation from the 1986 accident was negligible from a health standpoint. I know of no evidence that that accident caused any increase in cancer in this country," Iwamoto said.

What about kids? I've heard they're more sensitive to radiation.

That is true. "Kids are more vulnerable to radiation for a couple of reasons," said Dr. William Hendee, a radiation physicist with the Medical College of Wisconsin. "Their organs and tissues are growing and developing. Growing and developing cells are more susceptible to radiation. Kids also have a longer lifespan."

So should I keep them away from school?

No. Radiation levels are not likely to get very high. There is no reason to keep your kids out of school.

Should I take iodine tablets or eat iodized salt? It can't hurt, can it?

Well, yes, it can hurt. The tablets can be risky for some people — especially pregnant women. There is no reason to take iodine tablets at this point, said California officials at the news conference.

Indeed, potassium iodide is not recommended at all until radiation levels hit the tens of thousands of microsieverts. Levels won't reach anywhere approaching that level here.

In cases of true radiation exposure — for example, for people living close to the reactors in Japan — the benefits of potassium iodide outweigh the risks. The tablets can protect the thyroid from exposure to radioactive iodine-131 by "filling up" the gland and preventing it from taking up the radioactive iodine.

But potassium iodide can be harmful to people who are allergic to the substance or who have the skin disorders dermatitis herpetiformis or urticaria vasculitis, according to the Centers for Disease Control and Prevention. Pregnant women and infants should not be given potassium iodide because it could cause a serious thyroid disorder in infants. The supplements can cause some side effects including nausea, rashes and inflammation of the salivary glands.

As for eating iodized table salt to ward off the effects of radiation, that might work, but you'd have to gobble a great deal of the stuff — 3 1/2 pounds a day, according to the Salt Institute, an industry group — to reach the 130 milligrams of iodine you'd need. Even the institute said, in a statement, that this was not a good primary defense against radioactive fallout. That's saying something. Don't do it.

Would wearing a mask help me?

Sure, if it gives you peace of mind. "Masks would reduce a bit of the inhalation, but the amount of radioactive fallout is going to be so tiny," Hendee said. "For someone who is concerned or worried, if they felt better wearing a mask, they should wear a mask. I don't think it will reduce their risk, because the risk is already so low."

Should I stay indoors?

That's probably not necessary, unless local authorities alert you to do so. Currently, federal officials aren't recommending it.

What contingency plans do local and national health authorities have?

Although national health authorities defer to state governments, they will issue recommendations based on the severity of radiation levels, said Robert Taylor, a spokesman for the Nuclear Regulatory Commission. Possible recommendations include evacuating areas within 10 miles of a nuclear power plant, warning people to take shelter and close all doors and windows, and advising residents to consume potassium iodide tablets. "There's no need for U.S. citizens to take any protective measures at this time," he added.

What can I do to be safer?

Until more is known about the threat radiation from the nuclear plant might pose in California and beyond, your best bet is to get yourself prepared — for any expected emergency. Assemble your earthquake kit. Install gas shut-off valves, if your house doesn't already have them, "rather than going out and buying potassium iodide, I would encourage everyone to go out and buy three to five days of food and water, so that when we have our earthquake, you can be self-sufficient," said Howard Backer, interim director of the California Department of Public Health, at the news conference.

Most of all, address the health threats that you can control. According to the federal government, almost 1.5 million Americans die each year of heart disease or tobacco-related diseases. The best bang for your buck might be throwing away the cigarettes, exercising and improving your diet.

Photos: In Japan, life amid crisis

More: Articles, videos and graphics on radiation exposure, nuclear crisis

eryn.brown@latimes.com