The Radiation Effect

Radiation occurs in two forms, non-ionizing and ionizing. While non-ionizing radiation does not carry enough energy to become mutagenic, exposure to ionizing radiation carries medical implications over time. The radiation effects produced by exposure to ionizing radiation are caused by energy that severely damages living tissue, leading to damage of DNA or death.

Types of Radiation

• There are four types of ionizing radiation: gamma, neutron, beta and alpha. Each type interacts with human tissue in different ways, which creates a varying degree of danger. Neutron and gamma radiation are more dangerous, with the most penetrating energy that causes deposition of radiation throughout the body.

Time Frame/Dosage

• The radiation dose rate is the most effective way to measure the absorption of radiation into tissue. The dose is measured using the rad, the unit of absorbed dose. The relative biological effectiveness factor measures the amount of radiation needed to have the same biological effect as other types of radiation. The lethal dose of radiation is dependent on age since the elderly and young are more susceptible to radiation effects. In cases of nuclear fallout, additional exposure occurs after the initial blast during early fallout, within the first two weeks after the blast.

Short-Term Effects

• Acute radiation syndrome is caused by exposure to doses of ionizing radiation over a short period of time, resulting in symptoms classified as radiation sickness. These acute effects may begin within one to two hours after exposure and can include nausea, headaches, diarrhea, dehydration, intestinal cramps and loss of appetite. Exposure to larger doses of ionizing radiation results in more serious symptoms caused by damage to the lymphatic tissue and bone marrow. Blood producing cells slowly die and are not replaced, resulting in a shortage of blood cells, which leads to infection and anemia. A shortage of these cells also causes fatigue, bleeding and weakness. Other symptoms of acute radiation sickness include hair loss and discoloration of the skin.

Long-Term Effects

• Long-term effects of ionizing radiation exposure present themselves after a number of years. The most common late effect of radiation includes an increased incidence or an accelerated onset time of cancer. Ionizing radiation impacts reproductive function by creating a loss of sexual desire, abnormal menstruation in women and reduced sperm counts in men. Additionally, women who are exposed to radiation during pregnancy can expect developmental effects and birth defects on the child. Birth defects caused by exposure include a smaller head size, mental retardation and stunted growth. Lastly, the incidence of cataract formation increases with higher radiation dosage, causing vision loss and blindness.

Examples of Symptoms

• Radiation exposure can have numerous effects on the body. When brain cells become damaged, they cannot be repaired, which can cause seizures and death. A reduction in a person's blood cell count makes her more susceptible to infection. A high exposure to radiation damages blood vessels causing heart failure, and damage to the gastrointestinal tract leads to nausea, diarrhea and vomiting blood.