CHM333:

Effects of Nuclear Radiation on the Human Body

Why nuclear radiation is harmful to the human body:

Source

Decaying radioactive materials release alpha, beta, or gamma particles. These particles have enough to energy to pull electrons away from atoms, or even break chemical bonds. This can damage any living tissue in the human body. The body will often try to repair the damage caused by these broken chemical bonds. If, however, the radiation exposure is too strong, the damage will be permanent. Other times the body will make mistakes in its natural repairing process. The effects incurred from radiation are a function of the time and strength of the exposure. There are two broad categories that describe the different effects of radiation exposure: stochastic and non-stochastic. Stochastic effects are characterized by long-term, low-level exposure to radiation. Non-stochastic effects are characterized by short-term, but high-level exposure to radiation.

Stochastic Health Effects

The most common effect of long-term, low-level radiation exposure is cancer. Damage occurring in cells and molecules in the body due to radiation exposure can cause the body's natural control system for cell growth to malfunction. The cell growth control malfunction permits cancer cells to grow uncontrollably. This is why radiation is considered to be highly carcinogenic.

Radiation can also cause mutations in DNA. DNA is used by the body to make exact replications of existing cells; hence these mutations can cause permanent changes to the cells a body makes. Sometimes the body can fix these mutations, other times, it can even create a new mutation during the repair. There are two types of mutations- teratogenic or genetic. Teratogenic mutations only affect the exposed individual, whereas genetic mutations can be passed on to the offspring of the effected individual.1

Non-Stochastic Health Effects

Non-stochastic health effects typically result from some type of nuclear accident that entails exposure to copious amounts of nuclear radiation. These effects of are directly proportional to the magnitude of the exposure.

Exposure to 5-10 rem of radiation is likely to cause severe burns, and possible changes in blood chemistry. Exposure to 50 rem is known to induce nausea, damage bone marrow, and cause fatigue within hours. Fifty rem exposure will also cause hair loss in 2-3 weeks and can lead to death within two months. Exposure to 1000 rem will likely cause destruction of intestinal lining, internal bleeding, and death within 1-2 weeks. Doses of radiation above 2000 rem will cause immediate damage to the nervous system and unconsciousness in minutes, followed by death in hours to days.2

Extreme exposure to radiation often causes acute radiation syndrome. This is characterized by excessive amounts of radiation being stored in bone tissue and marrow, creating a cancer. This leads to a reduction of white blood cells, which in turn leads to decreases in red blood cell levels. Victims of acute radiation syndrome have reported nausea and vomiting in the first few hours after exposure. They reportedly feel normal for several days, but are suddenly stricken with anemia due to the rapid loss of red blood cells. This in turn causes intestinal bleeding and decreases the ability of wounds to heal. The depletion of white blood cells leads to the body's immune system to become diminished. Death can follow in weeks or months.

Victims are likely to recover from acute radiation syndrome within a few months if their exposure was less than 400 rem. Only 50% of the victims exposed to more than 400 rem of radiation usually survive.3