AusSMC: As the situation unfolds following the earthquake and tsunami in Japan, experts look at the health effects of exposure to radiation.
The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) have added more information to their website. See below for an explanation of the Sievert unit measure used to quantitatively assess the biological effects of exposure to radiation.
Our colleagues at the AusSMC gathered the comments below.
Feel free to use these quotes in your stories. Any further comments will be posted on the AusSMC website at www.aussmc.org. If you would like to speak to one of the experts quoted below, please contact the AusSMC on (+61 8) 7120 8666 or by email (email@example.com).
Dr Pradip Deb is a Senior Lecturer in Medical Radiations at the School of Medical Sciences, RMIT University:
“400 millisieverts is equivalent to 4000 x-ray exposure, which is very high, but if people are exposed for only a few minutes, even if for an hour – the dose is 400 mSv – which is sublethal.” [Please see exposure level classifications below]
“High levels of radiation exposure to human body can cause severe problems in human body functions. An exposed person will show the symptoms of acute radiation sickness in different levels, depending on the amount and nature of radiation exposure. If a person is exposed to a significant amount of radiation over a short period of time, that is, acute exposure, this can cause radiation sickness or death shortly after exposure. If they survive there is a possibility of developing cancer in later years.”
“Each person differs in their biological response to a given amount of radiation depending on their age, sex, lifestyle, diet, body temperature, overall medical health etc. In general children and elderly person are more sensitive to radiation. The severity of acute radiation sickness depends on how much radiation is received, how much of the body is exposed and the sensitivity of the exposed individual to radiation.”
“There are four stages of acute radiation sickness – prodromal phase (within 48 hours), latent phase (days to weeks), manifest illness (weeks to months) and the fourth phase, which is recovery or death. If the radiation level is excessively high all four phases can appear within 48 hours.”
“Radiation exposure causes the changes in blood cells (white blood cells decrease very fast), effects in gastrointestinal cells (causing nausea, vomiting, diarrhoea), fever, non-specific flu-like symptoms, hair loss, fatigue. The basic three things about radiation protection is distance, shielding, and time. More distance from the radiation source, proper shielding, and less exposure time will reduce the exposure level of radiation. The exposed person should be isolated for treatment, as they can cause secondary radiation exposure to others.”
“Severity level of radiation dose can be estimated according to radiation level or effective dose. Radiation exposure levels (dose) can be classified as follows:
Less than 2.5 Sievert (2500 mSv) – sublethal dose
Symptoms may include: Malaise, Fatigue, Drowsiness, Weight loss, Fever, Abdominal pain, Insomnia, Restlessness, Blisters
2.5 Sv – 6.5 Sv (2500 mSv – 6500 mSv) – Potentially lethal dose
· Significant reduction in production of blood cells
· Nausea/vomiting which appears to get better in 3 days
· WBC greatly reduced
· After two weeks: chills, fatigue, ulceration of the mouth
6.5 Sv – 10 Sv (6500 mSv – 10000 mSv) – supralethal dose
· Damage to the stomach lining and/or intestine -Causing decreased absorption, ulceration and dehydration
· Seven Days After Exposure
– Severe infection, fluid loss, blood loss or collapse of the circulatory system and may result in death
Acute Doses over 10 Sv (10000 mSv)
· Irreparable damage to the brain and spinal cord
-Lack of coordination
-Occasional periods of disorientation
-Death occurs within hours to days
Comparison with diagnostic x-ray exposure:
Typical effective dose for one exposure of chest x-ray is 0.1 mSv. Which is very small compared to our normal radiation acceptance level (20 mSv per year).
Statement from the Food Standards Australia New Zealand (FSANZ):
“Food Standards Australia New Zealand is conducting an investigation on the possible risk of radiation-contaminated food entering Australia from Japan and will provide advice to the Australian Quarantine and Inspection Service to assist them in determining what additional border action is needed, if any. Australia imports very little food from Japan and that is limited to a small range of specialty products (such as small volumes of seaweed and sake as well as other Japanese specialty food products such as mirin, soy sauce, dried noodles, pickled ginger, wasabi).”
You can contact FSANZ media on +61 401 714 265