Radiation Exposure – What is Radiation Exposure?

Posted on Jan 23, 2014 in Environment, Medical Rewind

Radiation exposure / poisoning, or radiation sickness is a form of damage to organ tissue caused by excessive exposure to ionizing radiation. The term is generally used to refer to acute problems caused by a large dosage of radiation in a short period, though this also has occurred with long term exposure.

The clinical name for radiation sickness is acute radiation syndrome (ARS) as described by the CDC. A chronic radiation syndrome does exist but is very uncommon; this has been observed among workers in early radium source production sites and in the early days of the Soviet nuclear program. A short exposure can result in acute radiation syndrome; chronic radiation syndrome requires a prolonged high level of exposure.

Radiation exposure can also increase the probability of developing some other diseases, mainly cancer, tumours, and genetic damage. These are referred to as the stochastic effects of radiation, and are not included in the term radiation sickness.

The use of radionuclides in science and industry is strictly regulated in most countries. In the event of an accidental or deliberate release of radioactive material, either evacuation or sheltering in place are the recommended measures.

Radiation Exposure Symptoms

Radiation exposure sickness is generally associated with acute (a single large) exposure. Nausea and vomiting are usually the main symptoms. The symptoms of radiation sickness become more serious (and the chance of survival decreases) as the dosage of radiation increases.

A few symptom-free days may pass between the appearance of the initial symptoms and the onset of symptoms of more severe illness associated with higher doses of radiation.

Nausea and vomiting generally occur within 24–48 hours after exposure to mild (1–2 Sv) doses of radiation. Radiation damage to the intestinal tract lining will cause nausea, bloody vomiting and diarrhea. This occurs when the victim’s exposure is 200 rems (1 Sv = 100 rems) or more. The radiation will begin to destroy the cells in the body that divide rapidly.

These including blood, GI tract, reproductive and hair cells, and harms the DNA and RNA of surviving cells. Headache, fatigue, and weakness are also seen with mild exposure. Moderate (2–3.5 Sv of radiation) exposure is associated with nausea and vomiting beginning within 12–24 hours after exposure. 1 rem=0.01 Sv).

Annual limit on intake (ALI) is the derived limit for the amount of radioactive material taken into the body of an adult worker by inhalation or ingestion in a year. ALI is the intake of a given radionuclide in a year that would result in:

  • a committed effective dose equivalent of 0.05 Sv (5 rems) for a “reference human body”, or
  • a committed dose equivalent of 0.5 Sv (50 rems) to any individual organ or tissue,

whatever dose is the smaller.

Phase Symptom Exposure (Sv)
1–2Sv 2–6Sv 6–8Sv 8–30Sv >30Sv
Immediate Nausea and vomiting 5–50% 50–100% 75–100% 90–100% 100%
”Time of onset” 2–6h 1–2h 10–60m <10m immediate
”Duration” <24h 24–48h >48h >48h 48h–death
Diarrhea None Slight (10%) Heavy (10%) Heavy (90%) Heavy (100%)
”Time of onset” 3–8h 1–2h <1h <30m
Headache Slight Mild (50%) Moderate (80%) Severe (80–90%) Severe (100%)
”Time of onset 4–24h 3–4h 1–2h <1h
Fever Slight–None Moderate (50%) High (100%) Severe (100%) Severe (100%)
”Time of onset 1–3h <1h <1h <30m
CNS function No impairment Cognitive impairment 6–20 h Cognitive impairment >20 h Rapid incapacitation Seizures, Tremor, Ataxia
Latent Period 28–31 days 7–28 days <7 days none none
Overt illness Mild Leukopenia;
Severe leukopenia;
High fever;
Dizziness and disorientation Hypotension;
Electrolyte disturbance
Vomiting; Severe diarrhea;
High fever;
Electrolyte disturbance;
Mortality without medical care 0–5% 5–100% 95–100% 100% 100%
Mortality with medical care 0–5% 5–50% 50–100% 100% 100%

Source:  News-Medical.Net