Arquivo da tag: Radioatividade

Cold War nuke tests changed rainfall (Science Daily)

Radioactive period following nuclear bomb tests changed rainfall patterns thousands of miles from the detonation sites

Date: May 13, 2020

Source: University of Reading

Summary: Historic records from weather stations show that rainfall patterns in Scotland were affected by charge in the atmosphere released by radiation from nuclear bomb tests carried out in the 1950s and ’60s.

Nuclear bomb tests during the Cold War may have changed rainfall patterns thousands of miles from the detonation sites, new research has revealed.

Scientists at the University of Reading have researched how the electric charge released by radiation from the test detonations, carried out predominantly by the US and Soviet Union in the 1950s and 1960s, affected rainclouds at the time.

The study, published in Physical Review Letters, used historic records between 1962-64 from a research station in Scotland. Scientists compared days with high and low radioactively-generated charge, finding that clouds were visibly thicker, and there was 24% more rain on average on the days with more radioactivity.

Professor Giles Harrison, lead author and Professor of Atmospheric Physics at the University of Reading, said: “By studying the radioactivity released from Cold War weapons tests, scientists at the time learnt about atmospheric circulation patterns. We have now reused this data to examine the effect on rainfall.

“The politically charged atmosphere of the Cold War led to a nuclear arms race and worldwide anxiety. Decades later, that global cloud has yielded a silver lining, in giving us a unique way to study how electric charge affects rain.”

It has long been thought that electric charge modifies how water droplets in clouds collide and combine, potentially affecting the size of droplets and influencing rainfall, but this is difficult to observe in the atmosphere. By combining the bomb test data with weather records, the scientists were able to retrospectively investigate this.

Through learning more about how charge affects non-thunderstorm clouds, it is thought that scientists will now have a better understanding of important weather processes.

The race to develop nuclear weapons was a key feature of the Cold War, as the world’s superpowers sought to demonstrate their military capabilities during heightened tensions following the Second World War.

Although detonations were carried out in remote parts of the world, such as the Nevada Desert in the US, and on Pacific and Arctic islands, radioactive pollution spread widely throughout the atmosphere. Radioactivity ionises the air, releasing electric charge.

The researchers, from the Universities of Reading, Bath and Bristol, studied records from well-equipped Met Office research weather stations at Kew near London and Lerwick in the Shetland Isles.

Located 300 miles north west of Scotland, the Shetland site was relatively unaffected by other sources of anthropogenic pollution. This made it well suited as a test site to observe rainfall effects which, although likely to have occurred elsewhere too, would be much more difficult to detect.

Atmospheric electricity is most easily measured on fine days, so the Kew measurements were used to identify nearly 150 days where there was high or low charge generation over the UK while it was cloudy in Lerwick. The Shetland rainfall on these days showed differences which vanished after the major radioactivity episode was over.

The findings may be helpful for cloud-related geoengineering research, which is exploring how electric charge could influence rain, relieve droughts or prevent floods, without the use of chemicals.

Professor Harrison is leading a project investigating electrical effects on dusts and clouds in the United Arab Emirates, as part of their national programme in Rain Enhancement Science. These new findings will help to show the typical charges possible in natural non-thunderstorm clouds.

Urânio contamina água na Bahia (Estadão)

JC, 5246, 24 de agosto de 2015

Há 15 anos extração em única mina explorada na América Latina é feita pela Indústrias Nucleares do Brasil, estatal federal que sempre negava problema

Uma tampa de ferro cobre a boca do poço, no sítio de Osvaldo Antônio de Jesus. A proteção enferrujada tem um furo no meio. Abaixo dela, um reservatório com 90 metros de profundidade está cheio d’água. Osvaldo ergue a tampa e aponta o líquido, um bem precioso para quem vive por esses cantos de Lagoa Real, no sertão da Bahia. Por cerca de um ano, foi esse o poço que garantiu boa parte do consumo diário de sua família. Há poucas semanas, porém, nenhuma gota pôde mais ser retirada dali. Sua água está contaminada por urânio.

Veja o texto na íntegra:,uranio-contamina-agua-na-bahia,1748686

(André Borges e Dida Sampaio/O Estado de S.Paulo)

Boom Town: atomic tourism blooms in a Western desert (Al Jazeera America)

As nuclear age approaches eighth decade, visitors flock to historic bomb craters at New Mexico test sites

TRINITY SITE, New Mexico — Standing a few yards from the spot where the world’s first atomic bomb detonated with a blast so powerful that it turned the desert sand to glass and shattered windows more than 100 miles away, tourist Chris Cashel explained what drew him here.

“You don’t get to go to very many places that changed the entire world in a single moment,” said Cashel as he glanced around the windswept, desolate Trinity Site in the New Mexico desert packed with tourists. “The world was never going to be the same after that.”

The military veteran was among thousands of visitors who piled into cars and buses to drive out to the secluded site about 35 miles southeast of Socorro, where Manhattan Project scientists split the atom shortly before dawn on July 16, 1945, ushering in the atomic age. The successful test of the nuclear “gadget” unleashed a blast equivalent to 19 kilotons of high explosive, and led to the devastation of the Japanese cities of Hiroshima and Nagasaki weeks later.

The sagebrush-ringed spot lies on the White Sands Missile Range and is the most famous of a number of U.S. atomic weapon-related tourist attractions, as the nuclear age approaches its 70th anniversary next year. The popular, informal trail includes tours to the former Cold War bomb proving grounds in Nevada that are routinely booked up months ahead, as well as popular tours of an inter-continental ballistic missile silo hidden deep beneath the Arizona desert.

Legislation, meanwhile, to create a Manhattan Project National Historical Park to preserve sites in New Mexico, Tennessee and Washington state related to the project led by physicist Robert Oppenheimer is currently beingconsidered by Congress.

The Trinity Site “open house” earlier this month drew about 4,000 visitors from as far afield as Germany, Japan and the United Kingdom, who beat a trail out to the spot where the explosion created heat so intense it felt “like opening an oven door, even at ten miles,” according to one eyewitness account.

Visitors milled around ground zero and scoured the ground for fragments of green “Trinitite” — a glass-like substance forged from superheated sand sucked up into the world’s first nuclear fireball — and posed for photographs by a stone obelisk marking the blast’s hypocenter. “There are all kinds of reasons for coming,” said Jim Eckles, a docent at the site explaining its powerful allure. “There are kids here for their science class. There are World War Two vets here because they’ll tell you it saved their life. They didn’t have to go to the Pacific to fight the Japanese, island to island to island.”

Visitors milled around ground zero and scoured the ground for fragments of green “Trinitite” — a glass-like substance forged from superheated sand sucked up into the world’s first nuclear fireball.


Massive Sedan Crater, 320ft deep in desert. National Nuclear Security Administration

As World War Two segued into the Cold War, the sparsely populated U.S. West became key in the scramble to develop, test and deploy ever more powerful nuclear weapons. The region was a vital part of America’s rivalry with the Soviet Union. But there was an unexpected side effect — a tourism industry was also born.

During the heyday of above-ground testing at the former Nevada Test Site in the 1950s and early 1960s, hoteliers in Las Vegas 65 miles away cashed in by offering “Atomic Cocktails” and a “Miss Atomic Blast” beauty pageant. Parties to view the curling mushroom clouds were also a popular draw.

That fascination is still there. Tours to the site where 1,021 nuclear detonations were carried out between 1951 and 1992 are currently booked up through December. No cameras, binoculars or tape recorders are allowed, and background checks are required for all visitors to the area, since renamed the Nevada National Security Site.

The highlight is “doom town” — houses, bomb shelters and even a steel and concrete bank vault — built to see how they stood up to a nuclear onslaught. The homes were painted, furnished and populated with eerily lifelike mannequins dressed in the latest fashions donated by a Las Vegas department store.

Visitors also get to see the Sedan Crater, a 1,280-foot wide and 320-foot deep depression formed by a 104-kiloton blast to test the feasibility of using nuclear bombs for peaceful activities such as mining and construction – an idea almost unthinkable now.

The Southwest atomic trail also includes the Titan Missile Museum, a silo hidden deep beneath the desert south of Tucson, Arizona, which houses a decommissioned inter-continental ballistic missile (ICBM) that was on the front line of the Cold War from 1963 to 1987. The ten-story tall Titan II was topped with a nine-megaton thermonuclear warhead – hundreds of times more powerful than the Trinity device. Capable of launching in 58 seconds, it could reach its target more than 6,300 miles away in about 30 minutes.

That level of destruction disturbs some who visit. “It’s kind of humbling,” said John, an 18-year-old student from Minnesota, who sat in a chair at the command center and initiated a simulated launch sequence. “Someone can turn a key and in a split second destroy an entire city, miles and miles away.”

Atomic tour

Decommissioned ICBM. Titan Missile Museum

Arms-reduction agreements cut strategic nuclear weapon stockpiles by about 80 percent after the Cold War ended. The diminishing fear of a nuclear doomsday, together with increased access to some of the previously classified weapon-related sites, is spurring interest in the sites today, experts said.

“You have basically an entire generation that has grown up with the thought of nuclear annihilation as something that is historical,” said Sharon Weinberger, co-author with Nathan Hodge of “A Nuclear Family Vacation: Travels in the World of Atomic Weaponry.”

“There’s also more and more of these sites that are now accessible and being decommissioned,” she added.

For those drawn to the attractions scattered across the rugged West, the experience is invariably thought-provoking. The visit left Socorro resident Mary Bjorklund pondering whether the bomb’s terrible destructive power had brought any net benefit. “I will think about all the people that lost their lives in Japan. Then I will think about all the people that it was supposed to save by ending World War Two. It makes you thoughtful,” she said.

Among visitors on a fully-booked tour of the Titan Missile Museum was a retired U.S. Air Force officer, Randy Hartley, who served on the crew at the site from 1978 to 1982. Living for years with the ever-present possibility of having to launch a retaliatory nuclear strike made him particularly philosophical about the atomic age.

“I think that anyone who has been associated with these weapons would wish they had never been around, would wish that we had never done the Trinity bomb or the Manhattan Project … But you can’t put the genie back in the bottle,” he said. “I want people to understand the fear and the horror of these weapons, to propel us to do what we can do to break down barriers between our fellow inhabitants of this earth.”

Fukushima Forever (Huff Post)

Charles Perrow

Posted: 09/20/2013 2:49 pm

Recent disclosures of tons of radioactive water from the damaged Fukushima reactors spilling into the ocean are just the latest evidence of the continuing incompetence of the Japanese utility, TEPCO. The announcement that the Japanese government will step in is also not reassuring since it was the Japanese government that failed to regulate the utility for decades. But, bad as it is, the current contamination of the ocean should be the least of our worries. The radioactive poisons are expected to form a plume that will be carried by currents to coast of North America. But the effects will be small, adding an unfortunate bit to our background radiation. Fish swimming through the plume will be affected, but we can avoid eating them.

Much more serious is the danger that the spent fuel rod pool at the top of the nuclear plant number four will collapse in a storm or an earthquake, or in a failed attempt to carefully remove each of the 1,535 rods and safely transport them to the common storage pool 50 meters away. Conditions in the unit 4 pool, 100 feet from the ground, are perilous, and if any two of the rods touch it could cause a nuclear reaction that would be uncontrollable. The radiation emitted from all these rods, if they are not continually cool and kept separate, would require the evacuation of surrounding areas including Tokyo. Because of the radiation at the site the 6,375 rods in the common storage pool could not be continuously cooled; they would fission and all of humanity will be threatened, for thousands of years.

Fukushima is just the latest episode in a dangerous dance with radiation that has been going on for 68 years. Since the atomic bombing of Nagasaki and Hiroshima in 1945 we have repeatedly let loose plutonium and other radioactive substances on our planet, and authorities have repeatedly denied or trivialized their dangers. The authorities include national governments (the U.S., Japan, the Soviet Union/ Russia, England, France and Germany); the worldwide nuclear power industry; and some scientists both in and outside of these governments and the nuclear power industry. Denials and trivialization have continued with Fukushima. (Documentation of the following observations can be found in my piece in the Bulletin of the Atomic Scientists, upon which this article is based.) (Perrow 2013)

In 1945, shortly after the bombing of two Japanese cities, the New York Times headline read: “Survey Rules Out Nagasaki Dangers”; soon after the 2011 Fukushima disaster it read “Experts Foresee No Detectable Health Impact from Fukushima Radiation.” In between these two we had experts reassuring us about the nuclear bomb tests, plutonium plant disasters at Windscale in northern England and Chelyabinsk in the Ural Mountains, and the nuclear power plant accidents at Three Mile Island in the United States and Chernobyl in what is now Ukraine, as well as the normal operation of nuclear power plants.

Initially the U.S. Government denied that low-level radiation experienced by thousands of Japanese people in and near the two cities was dangerous. In 1953, the newly formed Atomic Energy Commission insisted that low-level exposure to radiation “can be continued indefinitely without any detectable bodily change.” Biologists and other scientists took exception to this, and a 1956 report by the National Academy of Scientists, examining data from Japan and from residents of the Marshall Islands exposed to nuclear test fallout, successfully established that all radiation was harmful. The Atomic Energy Commission then promoted a statistical or population approach that minimized the danger: the damage would be so small that it would hardly be detectable in a large population and could be due to any number of other causes. Nevertheless, the Radiation Research Foundation detected it in 1,900 excess deaths among the Japanese exposed to the two bombs. (The Department of Homeland Security estimated only 430 cancer deaths).

Besides the uproar about the worldwide fallout from testing nuclear weapons, another problem with nuclear fission soon emerged: a fire in a British plant making plutonium for nuclear weapons sent radioactive material over a large area of Cumbria, resulting in an estimated 240 premature cancer deaths, though the link is still disputed. The event was not made public and no evacuations were ordered. Also kept secret, for over 25 years, was a much larger explosion and fire, also in 1957, at the Chelyabinsk nuclear weapons processing plant in the eastern Ural Mountains of the Soviet Union. One estimate is that 272,000 people were irradiated; lakes and streams were contaminated; 7,500 people were evacuated; and some areas still are uninhabitable. The CIA knew of it immediately, but they too kept it secret. If a plutonium plant could do that much damage it would be a powerful argument for not building nuclear weapons.

Powerful arguments were needed, due to the fallout from the fallout from bombs and tests. Peaceful use became the mantra. Project Plowshares, initiated in 1958, conducted 27 “peaceful nuclear explosions” from 1961 until the costs as well as public pressure from unforeseen consequences ended the program in 1975. The Chairman of the Atomic Energy Commission indicated Plowshares’ close relationship to the increasing opposition to nuclear weapons, saying that peaceful applications of nuclear explosives would “create a climate of world opinion that is more favorable to weapons development and tests” (emphasis supplied). A Pentagon official was equally blunt, saying in 1953, “The atomic bomb will be accepted far more readily if at the same time atomic energy is being used for constructive ends.” The minutes of a National Security Council in 1953 spoke of destroying the taboo associated with nuclear weapons and “dissipating” the feeling that we could not use an A-bomb.

More useful than peaceful nuclear explosions were nuclear power plants, which would produce the plutonium necessary for atomic weapons as well as legitimating them. Nuclear power plants, the daughter of the weapons program — actually its “bad seed” –f was born and soon saw first fruit with the1979 Three Mile Island accident. Increases in cancer were found but the Columbia University study declared that the level of radiation from TMI was too low to have caused them, and the “stress” hypothesis made its first appearance as the explanation for rises in cancer. Another university study disputed this, arguing that radiation caused the increase, and since a victim suit was involved, it went to a Federal judge who ruled in favor of stress. A third, larger study found “slight” increases in cancer mortality and increased risk breast and other cancers, but found “no consistent evidence” of a “significant impact.” Indeed, it would be hard to find such an impact when so many other things can cause cancer, and it is so widespread. Indeed, since stress can cause it, there is ample ambiguity that can be mobilized to defend nuclear power plants.

Ambiguity was mobilized by the Soviet Union after the 1987 Chernobyl disaster. Medical studies by Russian scientists were suppressed, and doctors were told not to use the designation of leukemia in health reports. Only after a few years had elapsed did any serious studies acknowledge that the radiation was serious. The Soviet Union forcefully argued that the large drops in life expectancy in the affected areas were due to not just stress, but lifestyle changes. The International Atomic Energy Association (IAEA), charged with both promoting nuclear power and helping make it safe, agreed, and mentioned such things as obesity, smoking, and even unprotected sex, arguing that the affected population should not be treated as “victims” but as “survivors.” The count of premature deaths has varied widely, ranging from 4,000 in the contaminated areas of Ukraine, Belarus and Russia from UN agencies, while Greenpeace puts it at 200,000. We also have the controversial worldwide estimate of 985,000 from Russian scientists with access to thousands of publications from the affected regions.

Even when nuclear power plants are running normally they are expected to release some radiation, but so little as to be harmless. Numerous studies have now challenged that. When eight U.S. nuclear plants in the U.S. were closed in 1987 they provided the opportunity for a field test. Two years later strontium-90 levels in local milk declined sharply, as did birth defects and death rates of infants within 40 miles of the plants. A 2007 study of all German nuclear power plants saw childhood leukemia for children living less than 3 miles from the plants more than double, but the researchers held that the plants could not cause it because their radiation levels were so low. Similar results were found for a French study, with a similar conclusion; it could not be low-level radiation, though they had no other explanation. A meta-study published in 2007 of 136 reactor sites in seven countries, extended to include children up to age 9, found childhood leukemia increases of 14 percent to 21 percent.

Epidemiological studies of children and adults living near the Fukushima Daiichi nuclear plant will face the same obstacles as earlier studies. About 40 percent of the aging population of Japan will die of some form of cancer; how can one be sure it was not caused by one of the multiple other causes? It took decades for the effects of the atomic bombs and Chernobyl to clearly emblazon the word “CANCER” on these events. Almost all scientists finally agree that the dose effects are linear, that is, any radiation added to natural background radiation, even low-levels of radiation, is harmful. But how harmful?

University professors have declared that the health effects of Fukushima are “negligible,” will cause “close to no deaths,” and that much of the damage was “really psychological.” Extensive and expensive follow-up on citizens from the Fukushima area, the experts say, is not worth it. There is doubt a direct link will ever be definitively made, one expert said. The head of the U.S. National Council on Radiation Protection and Measurements, said: “There’s no opportunity for conducting epidemiological studies that have any chance of success….The doses are just too low.” We have heard this in 1945, at TMi, at Chernobyl, and for normally running power plants. It is surprising that respected scientists refuse to make another test of such an important null hypothesis: that there are no discernible effects of low-level radiation.

Not surprisingly, a nuclear power trade group announced shortly after the March, 2011 meltdown at Fukushima (the meltdown started with the earthquake, well before the tsunami hit), that “no health effects are expected” as a result of the events. UN agencies agree with them and the U.S. Council. The leading UN organization on the effects of radiation concluded “Radiation exposure following the nuclear accident at Fukushima-Daiichi did not cause any immediate health effects. It is unlikely to be able to attribute any health effects in the future among the general public and the vast majority of workers.” The World Health Organization stated that while people in the United States receive about 6.5 millisieverts per year from sources including background radiation and medical procedures, only two Japanese communities had effective dose rates of 10 to 50 millisieverts, a bit more than normal.

However, other data contradict the WHO and other UN agencies. The Japanese science and technology ministry (MEXT) indicated that a child in one community would have an exposure 100 times the natural background radiation in Japan, rather than a bit more than normal. A hospital reported that more than half of the 527 children examined six months after the disaster had internal exposure to cesium-137, an isotope that poses great risk to human health. A French radiological institute found ambient dose rates 20 to 40 times that of background radiation and in the most contaminated areas the rates were even 10 times those elevated dose rates. The Institute predicts and excess cancer rate of 2 percent in the first year alone. Experts not associated with the nuclear industry or the UN agencies currently have estimated from 1,000 to 3,000 cancer deaths. Nearly two years after the disaster the WHO was still declaring that any increase in human disease “is likely to remain below detectable levels.” (It is worth noting that the WHO still only releases reports on radiation impacts in consultation with the International Atomic Energy Agency.)

In March 2013, the Fukushima Prefecture Health Management Survey reported examining 133,000 children using new, highly sensitive ultrasound equipment. The survey found that 41 percent of the children examined had cysts of up to 2 centimeters in size and lumps measuring up to 5 millimeters on their thyroid glands, presumably from inhaled and ingested radioactive iodine. However, as we might expect from our chronicle, the survey found no cause for alarm because the cysts and lumps were too small to warrant further examination. The defense ministry also conducted an ultrasound examination of children from three other prefectures distant from Fukushima and found somewhat higher percentages of small cysts and lumps, adding to the argument that radiation was not the cause. But others point out that radiation effects would not be expected to be limited to what is designated as the contaminated area; that these cysts and lumps, signs of possible thyroid cancer, have appeared alarmingly soon after exposure; that they should be followed up since it takes a few years for cancer to show up and thyroid cancer is rare in children; and that a control group far from Japan should be tested with the same ultrasound technics.

The denial that Fukushima has any significant health impacts echoes the denials of the atomic bomb effects in 1945; the secrecy surrounding Windscale and Chelyabinsk; the studies suggesting that the fallout from Three Mile Island was, in fact, serious; and the multiple denials regarding Chernobyl (that it happened, that it was serious, and that it is still serious).

As of June, 2013, according to a report in The Japan Times, 12 of 175,499 children tested had tested positive for possible thyroid cancer, and 15 more were deemed at high risk of developing the disease. For a disease that is rare, this is high number. Meanwhile, the U.S. government is still trying to get us to ignore the bad seed. June 2012, the U.S. Department of Energy granted $1.7 million to the Massachusetts Institute of Technology to address the “difficulties in gaining the broad social acceptance” of nuclear power.

Perrow, Charles. 2013. “Nuclear denial: From Hiroshima to Fukushima.” Bulletin of Atomic Scientists 69(5):56-67.


The material contained in this chapter is based on official government sources as well as information provided by research institutions, policy organizations, peer-reviewed journals and eye witness accounts.

The CTBTO remains neutral in any ongoing disputes related to compensation for veterans of the nuclear test programmes.  

Nuclear weapons have been tested in all environments since 1945: in the atmosphere, underground and underwater. Tests have been carried out onboard barges, on top of towers, suspended from balloons, on the Earth’s surface, more than 600 metres underwater and over 200 metres underground. Nuclear test bombs have also been dropped by aircraft and fired by rockets up to 320 km into the atmosphere.

The National Resources Defense Council estimated the total yield of all nuclear tests conducted between 1945 and 1980 at 510 megatons (Mt). Atmospheric tests alone accounted for 428 mt, equivalent to over 29,000 Hiroshima size bombs.

Frigate Bird nuclear test explosion seen through the periscope of the submarine USS Carbonero (SS-337), Johnston Atoll, Central Pacific Ocean, 1962.

The first nuclear test was carried out by the United States in July 1945, followed by the Soviet Union in 1949, the United Kingdom in 1952, France in 1960, and China in 1964. The National Resources Defense Council estimated the total yield of all nuclear tests conducted between 1945 and 1980 at 510 megatons (Mt). Atmospheric tests alone accounted for 428 mt, equivalent to over 29,000 Hiroshima size bombs.

The amount of radioactivity generated by a nuclear explosion can vary considerably depending upon a number of factors. These include the size of the weapon and the location of the burst. An explosion at ground level may be expected to generate more dust and other radioactive particulate matters than an air burst. The dispersion of radioactive material is also dependent upon weather conditions.

Large amounts of radionuclides dispersed into the atmosphere

Levels of radiocarbon (C14) in the atmosphere 1945 – 2000. Image credit: Hokanomono.

The 2000 Report of the United Nations Scientific Committee on the Effects of Atomic Radiation to the General Assemblystates that:
“The main man-made contribution to the exposure of the world’s population [to radiation] has come from the testing of nuclear weapons in the atmosphere, from 1945 to 1980. Each nuclear test resulted in unrestrained release into the environment of substantial quantities of radioactive materials, which were widely dispersed in  the atmosphere and deposited everywhere on the Earth’s surface.”

The first nuclear test was carried out by the United States in July 1945, followed by the Soviet Union in 1949, the United Kingdom in 1952, France in 1960, and China in 1964.

Different types of nuclear tests: (1) atmospheric test; (2) underground test; (3) upper atmospheric test; and (4) underwater test.

Concern over bone-seeking radionuclides and the first mitigating steps

Prior to 1950, only limited consideration was given to the health impacts of worldwide dispersion of radioactivity from nuclear testing. Public protests in the 1950s and concerns about the radionuclide strontium-90 (see Chart 1) and its effect on mother’s milk and babies’ teeth were instrumental in the conclusion of the Partial Test Ban Treaty (PTBT) in 1963. The PTBT banned nuclear testing in the atmosphere, outer space and under water, but not underground, and was signed by the United States, the Soviet Union and the United Kingdom. However, France and China did not sign and conducted atmospheric tests until 1974 and 1980 respectively.

Although underground testing mitigated the problem of radiation doses from short-lived radionuclides such as iodine-131, large amounts of plutonium, iodine-129 and caesium-135 (See Chart 1) were released underground. In addition, exposure occurred beyond the test site if radioactive gases leaked or were vented.

Scientist arranging mice for radiation exposure investigations around 1944. (While conducting these experiments, the carcinogenesis of urethane was discovered).

Gradual increase in knowledge about dangers of radiation exposure

Over the past century, there has been a gradual accumulation of knowledge about the hazards of radioactivity. It was recognized early on that exposure to a sufficient radiation dosage could cause injuries to internal organs, as well as to the skin and the eyes.

According to the 2000 Report of the United Nations Scientific Committee on the Effects of Atomic Radiation to the UN General Assembly, radiation exposure can damage living cells, killing some and modifying others. The destruction of a sufficient number of cells will inflict noticeable harm on organs which may result in death. If altered cells are not repaired, the resulting modification will be passed on to further cells and may eventually lead to cancer. Modified cells that transmit hereditary information to the offspring of the exposed individual might cause hereditary disorders. Vegetation can also be contaminated when fallout is directly deposited on external surfaces of plants and absorbed through the roots. Furthermore, people can be exposed when they eat meat and milk from animals grazing on contaminated vegetation.

Radiation exposure has been associated with most forms of leukaemia, as well as cancer of the thyroid, lung and breast.

girl who lost her hair after being exposed to radiation from the bomb dropped on Hiroshima on 6 August 1945.

Studies reveal link between nuclear weapon testing and cancer

The American Cancer Society’s website explains how ionizing radiation, which refers to several types of particles and rays given off by radioactive materials, is one of the few scientifically proven carcinogens in human beings. Radiation exposure has been associated with most forms of leukaemia, as well as cancer of the thyroid, lung and breast. The time that may elapse between radiation exposure and cancer development can be anything between 10 and 40 years. Degrees of exposure regarded as tolerable in the 1950s are now recognized internationally as unsafe.

An article featured in Volume 94 of American Scientist onFallout from Nuclear Weapons Tests and Cancer Risksstates that a number of studies of biological samples (including bone, thyroid glands and other tissues) have provided increasing proof that specific radionuclides in fallout are implicated in fallout-related cancers.

It is difficult to assess the number of deaths that might be attributed to radiation exposure from nuclear testing. Some studies and evaluations, including an assessment by Arjun Makhijani on the health effects of nuclear weapon complexes, estimate that cancer fatalities due to the global radiation doses from the atmospheric nuclear testing programmes of the five nuclear-weapon States amount to hundreds of thousands. A 1991 study by the International Physicians for the Prevention of Nuclear War (IPPNW)estimated that the radiation and radioactive materials from atmospheric testing taken in by people up until the year 2000 would cause 430,000 cancer deaths, some of which had already occurred by the time the results were published. The study predicted that roughly 2.4 million people could eventually die from cancer as a result of atmospheric testing.


Radionuclide Half-life* Health hazards
6.7 hours Inhalation in excessive concentrations can result in dizziness, nausea, vomiting, loss of consciousness, and death. At low oxygen concentrations, unconsciousness and death may occur in seconds without warning.
432 years Moves rapidly through the body after ingestion and is concentrated within the bones for a long period of time. During this storage americium will slowly decay and release radioactive particles and rays. These rays can cause alteration of genetic materials and bone cancer.
8 days When present in high levels in the environment from radioactive fallout, I-131 can be absorbed through contaminated food. It also accumulates in the thyroid gland, where it can destroy all or part of the thyroid. May cause damage to the thyroid as it decays. Thyroid cancer may occur.
30 years After entering the body, caesium is distributed fairly uniformly through the body, with higher concentration in muscle tissue and lower concentration in bones. Can cause gonadal irradiation and genetic damage.
10.76 years Inhalation in excessive concentrations can result in dizziness, nausea, vomiting, loss of consciousness, and death.
28 years A small amount of strontium 90 is deposited in bones and bone marrow, blood and soft tissues when ingested. Can cause bone cancer, cancer of nearby tissues, and leukaemia.
24,400 years Released when a plutonium weapon is exploded. Ingestion of even a miniscule quantity is a serious health hazard and can cause lung, bone, and liver cancer. The highest doses are to the lungs, the bone marrow, bone surfaces, and liver.
12 years Easily ingested. Can be inhaled as a gas in the air or absorbed through the skin. Enters soft tissues and organs. Exposure to tritium increases the risk of developing cancer. Beta radiation emitted by tritium can cause lung cancer.

* ( i.e. amount of time it takes for half of the quantity of a radioactive material to decay)

Marie Curie won the Nobel Prize in chemistry in 1911 for her discovery of the elements radium and polonium. The curie unit is named after Marie and Pierre Curie, who conducted pioneering research on radiation.

Measuring radiation doses and biological risks

Scientists use different terms when measuring radiation. The terms can either refer to radiation from a radioactive source, the radiation dose absorbed by a person, or the risk that a person will suffer health effects from exposure to radiation. When a person is exposed to radiation, energy is deposited in the body’s tissues. The amount of energy deposited per unit of weight of human tissue is called the absorbed dose. This is measured using the rad or the SI Gy. The rad, which stands for radiation absorbed dose, has largely been replaced by the Gy. One Gy is equal to 100 rad.

The curie (symbol Ci) is a unit of radioactivity. It has largely been replaced by the Becquerel, which is the unit of radioactivity. One Becquerel is defined as the number of atoms which decay per second in a sample. The curie unit is named after Marie and Pierre Curie, who conducted pioneering research on radiation.

A person’s biological risk (i.e. the risk that a person will suffer health effects from an exposure to radiation) is measured using the conventional unit rem or the SI unit Sv.


Radiation dose in rems Health impact
5-20 Possible chromosomal damage.
20-100 Temporary reduction in number of white blood cells. Mild nausea and vomiting. Loss of appetite. Fatigue, which may last up to four weeks. Greater susceptibility to infection. Greater long-term risk of leukaemia and lymphoma is possible.
100-200 Mild radiation sickness within a few hours: vomiting, diarrhea, fatigue; reduced resistance to infection. Hair loss. In sufficient amounts, I-131 can destroy all or part of the thyroid gland, leading to thyroid abnormalities or cancer. Temporary male sterility.
200-300 Serious radiation sickness effects as in 100-200 rem. Body cells that divide rapidly can also be destroyed. These include blood cells, gastrointestinal tract cells, reproductive cells, and hair cells. DNA of surviving cells is also damaged.
300-400 Serious radiation sickness. Bone marrow and intestine destruction. Haemorraging of the mouth.
400-1000 Acute illness, possible heart failure. Bone marrow almost completely destroyed. Permanent female sterility probable.
1000-5000 Acute illness, nerve cells and small blood vessels are destroyed. Death can occur in days.