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Radiation poisoning

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Exposure levels

A gray (Gy) is a unit of radiation dose absorbed by matter. To gauge biological effects the dose is multiplied by a ‘quality factor’ which is dependent on the type of ionising radiation. Such measurement of biological effect is called “dose equivalent” and is measured in sievert (Sv). For electron and photon radiation (e.g. gamma), 1 Gy = 1 Sv.

The corresponding non-SI units are the rad (radiation absorbed dose; 1 rad = 0.01 Gy), and rem (roentgen equivalent mammal/man;[8] 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.[9]

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;
Fatigue;
Weakness
Leukopenia;
Purpura;
Hemorrhage;
Infections;
Epilation
Severe leukopenia;
High fever;
Diarrhea;
Vomiting;
Dizziness and disorientation Hypotension;
Electrolyte disturbance
Nausea;
Vomiting; Severe diarrhea;
High fever;
Electrolyte disturbance;
Shock
Death
Mortality without medical care 0–5% 5–100% 95–100% 100% 100%
Mortality with medical care 0–5% 5–50% 50–100% 100% 100%

[7][10]

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