Week 3 - Lecture 2 - Health and environmental impact of nuclear accidents

Question 1

Becquerel (Bq)

Answer 1

Unit indicating the amount of radioactivity

Question 2

Sievert (Sv)

Answer 2

Unit of radiation exposure dose that a person receives

1 mili-Sievert (mSv) is approximately equal to 1 in 10.000 to 1 in 20.000 risk of fatal cancer in later life

Question 3

Tritium

Answer 3

• Formed as a ‘’fission product’’ of uranium and Plutonium
• Slightly radioactive, which can harm our tissue
• Low radiotoxicity
• Does not bioaccumulate

Question 4

Physical half-life

Answer 4

Time for half of the radioactive isotope to decay

Question 5

Biological half-life

Answer 5

Time for the body to excrete half of the radioactive isotope ingested/inheld

Question 6

Effective half-life

Answer 6

Combines both physical half-life and biological half-life

Question 7

What can you do to limit your exposure to radiation?

Answer 7

• Move away from the source
• Avoid breathing in contaminated air or eating contaminated food
• Wash of particles on skin to avoid ingestion
• Give stable versions of radioactive isotopes to block uptake
• Individual doses from nuclear accidents much smaller than we think

Question 8

131-I

Iodine-131

Answer 8

• Has a short physical half-life (8 days) – within 3 months all the 131-I released from Chernobyl had decayed in the environment and no longer posed a radiological risk
• Major route of exposure through consumption of contaminated food and drink (milk) – minor exposure from inhalation
• 131-I is concentrated and stored in the thyroid gland, which results in high doses in a short period of time to the thyroid

Question 9

Cs-137

Caesium-137

Answer 9

• Cs-137 has a long physical half-life, but is not concentrated and stored in any tissue of the body – results in a low dose over a period of years

Question 10

Why is the thyroid sensitive to radiation?

Answer 10

• Thyroid takes up and stores iodine because thyroid hormones contain iodine.
• Entry and storage of radioiodine can be blocked by flooding the gland with non-radioactive iodine
• Iodine flux operates on the “last in, first out” principle – given too late stable iodine may increase exposed dose due to preventing efflux

Question 11

Why are children specifically sensitive when exposed to radiation?

Answer 11

1. Exposure
   - Milk, dairy produce
   - Small thyroid – larger dose to gland
2. Biology
   - Thyroid still developing
   - Increase in mutated clone size as a result of developmental growth, thus increasing the risk of cancer

Question 12

Disaster-related death (DRD)

Answer 12

A death caused by the deterioration of underlying mediacal problems due to poor medical access or illnesses arising from poor living environments, such as temporary shelters, in a disaster.

Question 13

External vs. Internal exposure

Answer 13

Exposure due to radiation outside the body and exposure from inside the body, respectively

Question 14

Radioactivity

Answer 14

The ability of some material to emitting radiation spontaneaously