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Radiation Effects on Humans

Radiation occurs when the unstable nuclei in atoms decompose. The particles they release are radiation. There are different types of radiation, depending on the type of particles released. In general, radiation can cause cancer, burns and in very high doses can kill. How much damage is done depends on the type of radiation and the length of exposure. Radiation causes genetic damage to cells, thus affecting their reproduction. Radiation is measured in the unit roentgen equivalents in man (rem).

  1. Hair Loss

    • A relatively low dose of radiation will often cause hair loss. The hair loss is a symptom of deeper internal cell damage with doses of between 200 and 300 or more rems. The annual limit for nuclear workers in the United States is 20 rems. Background radiation in many places is around 26 mili-rems, or .026 rems. The average chest x-ray exposes the patient to around 10 mili-rem, or around .01 rems. Cancer patients are commonly exposed to 5,000 mili-rems, or around 5 rems of radiation.

    Heart

    • Moderate doses of radiation can cause severe damage to capillaries, and thereby damage the heart. As the capillaries on the heart burst, the blood doesn't flow properly to the heart muscles and the risk of cardiac arrest is high. Exposure to between 1,000 and 5,000 rems could be enough to trigger death from heart failure.

    Brain

    • The cells of the brain, called neurons, don't reproduce. Because of this, they can withstand more radiation than other cells in the body. Brain cells don't tend to suffer damage until they are exposed to more than 5,000 rems. However, like the heart, damage can occur quickly to capillaries and other small blood vessels which can result in brain damage.

    Thyroid

    • The thyroid gland is very susceptible to radiation damage. In fact, radioactive iodine is prescribed in some cases of an overactive thyroid. The radiation in the iodine kills part of the thyroid, thus reducing its output of thyroid hormones.

    Blood System

    • A body's blood system has a number of functions. In addition to bringing oxygen to cells, it is key in fighting off infections. Doses as low as 100 rems can trigger a reduction in the blood's lymphocyte count and leave a person more prone to infection. Cases where a person has been exposed to a relatively low dose of radiation that causes flu like symptoms are often suffering from a drop in lymphocytes. This is often called a mild dose of radiation sickness. Symptoms can last for as long as ten years and patients experiencing mild radiation sickness are more susceptible to the cancers lymphoma and leukemia.

    Reproductive System

    • Reproductive cells divide quickly. As such, the reproductive system is very susceptible to radiation damage. Damage can occur with a dose as low as 200 rems. Many victims of radiation poisoning become sterile.

    Cancer

    • Radiation causes fundamental changes to the genetic, or DNA, structure of cells. This genetic damage sometimes results in cells growing out of control or not dying at the correct time. These cell growths form cancerous tumors.

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