Effects to the Human Body From Nuclear Fallout

Henry Shimp
April 23, 2017

Submitted as coursework for PH241, Stanford University, Winter 2017


Fig. 1: This map displays the level of radiation that different parts of the United States could have been exposed to due to Nuclear Fallout from nuclear testing. We cannot know for sure the amounts each person or state has been exposed to because fallout is simply dust; however, we can predict. [3] (Source: Wikimedia Commons)

Nuclear fallouts have major negative health impacts on humans in the area. Fallout is the condition following a nuclear bomb or reactor blowing up when radioactive particles and gases fall from and spread throughout the atmosphere. A particular danger in fallout is that because radioactive particles and gases can be carried be winds as they descend to the earth, such materials can be spread across a vast range of land, exposing many people to their harmful effects. Due to this, it has been found that everyone who has lived in the contiguous 48 states since 1951 has had a chance of exposure to radioactive fallout. The main reason for this is because these radioactive particles that "fallout" fall in the form of dust and that dust goes into the soil so they stay there for a long period of time which can lead to people being exposed to them. The primary method of contact between human and fallout particles is through direct contact with skin; however, eating plants, milk, or meat that have been exposed to fallout particles can also pose a risk to humans' health. [1]

How Radiation Affects the Body

Nuclear fallout poses health dangers, particularly in the form of cancer, to humans in the form of radiation. When radioactive chemicals break down they release a certain amount of radiation. When humans are exposed to this radiation there is a risk that it causes chemical changes in cells which can kill or makes cells abnormal. In damaging the DNA contained in cells, radiation can cause cancer and can also lead to birth defects in children due to the tampering with a person's genetic makeup. [2] The amount of radiation that the body is exposed to is measured in a unit known is the gray which is defined as the absorption of one joule of energy per kilogram of tissue. [1]

Cancer Dangers

Of the many dangers of radioactive exposure, thyroid exposure to I-131 is among the most detrimental to human health. People whose thyroid becomes exposed to I-131, especially during childhood years, have been proven to have an increased chance at developing thyroid disease and thyroid cancer later in life. The main method of thyroid exposure comes when children drink milk from cows and goats who have been exposed to radiation due to fallout dust from the soil and grass that they graze in. This is why fallout is so dangerous. [1] I-131 has lasting dangers to humans due to the fact that as it breaks down it releases radiation. This is a process that becomes less dangerous as time goes on and more radiation continues to release; however, the dangers remain as radiation is released into plants that are subsequently eaten by animals that are then eaten by humans. It is dangerous for humans to drink milk for multiple months after a nuclear test or reactor explosion because cows and goats either are exposed to the radiation directly or eat plants that are exposed to radiation which leads to danger in the milk that they produce. [2] The other highly feared chemical that is released to the environment in nuclear fallout is Strontium- 90. This chemical is among the most highly potent in the world as just one teaspoon would be enough to produce a dangerous level of radioactivity to every person alive. Strontium-90 attaches to the bones and teeth and proceeds to attack cells which can cause cancer. It has certain ability to penetrate into the bone marrow where red and white blood cells which are so vital to immune response are formed. Tampering with these processes can make it very difficult to overcome common diseases and germs that humans encounter. [2]


Due to the discovered dangers of fallout and the radioactivity it causes for humans, nuclear testing no longer takes place in America like it did during the cold war. The increased exposure to radiation from the testing had a negative effect on the health of American citizens. The United States government tested 1,127 nuclear bombs between 1945 and 1992, more than any other nation in the world. Because the testing took place all across the southern half of the United States, every state in the contiguous 48 could have been exposed to a level of nuclear radiation due to fallout as shown in Fig 1. While we cannot know for sure the exact amount of fallout that has occurred in each place, we can hypothesize the amounts in each state, and any fallout and therefore radiation poses a health risk to americans which is why it is unlikely that testing will resume anytime soon due to the health risks involved. [1]

© Henry Shimp. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] S. Simon, A. Bouville, and C. E. Land, "Fallout from Nuclear Weapons Test and Cancer Risks," Am. Sci. 94, 48 (2006).

[2] W. J. Schull and M. Otake, "Cognitive Function and Prenatal Exposure to Ionizing Radiation," Teratology 59, 222 (1999).

[3] Exposure of the American People to Iodine-131 from Nevada Nuclear-Bomb Tests (National Academies Press, 1999).