Radioactivity

Question 1

What were the outcomes of atomic bomb exposure?

Answer 1

Large population suddenly exposed to acute radiation dose; most deaths and immediate effects due to heat/explosion

Question 2

What did studies of atomic bomb survivors find?

Answer 2

40% higher incidence of leukaemia; 8% higher incidence of solid tumours; lifetime risk of fatal cancer about 12% (based on ~0.25 Sv exposure).

Question 3

Why was it difficult to assess radiation dose in survivors?

Answer 3

Difficult to assess amount of radiation each survivor received.

Question 4

What is radium and how was it used?

Answer 4

Radium is a daughter product of uranium; decays by emitting alpha radiation; used in paint in 20th century (self-luminescent).

Question 5

What were the risks associated with radium use?

Answer 5

Workers (mostly women) painted dials; dangers were known but suppressed.

Question 6

What are natural sources of environmental radiation?

Answer 6

Radiation is emitted by soil, rocks, houses, cosmic rays; levels depend on altitude and location.

Question 7

What is radon and its health risk?

Answer 7

Radon is a gaseous daughter product of uranium; decay products attach to airborne particles; leads to increased risk of lung cancer.

Question 8

What happened at Chernobyl?

Answer 8

One of two level 7 nuclear accidents; poor design and operation led to explosion and meltdown; ~14 EBq released (iodine-131 and caesium-137).

Question 9

What were the immediate effects on Chernobyl responders?

Answer 9

First responders received 8–20 Sv; 134 developed acute radiation sickness, 28 died.

Question 10

What were the long-term effects of Chernobyl?

Answer 10

Up to 600,000 involved in cleanup; increased doses; spike in thyroid cancers (especially paediatric); higher cancer rates in liquidators.

Question 11

What are the two types of radiation effects?

Answer 11

Somatic (evident in the individual) and hereditary.

Question 12

What are deterministic effects?

Answer 12

Dose related; minimum threshold; greater dose = greater severity (e.g. erythema, cataracts).

Question 13

What are stochastic effects?

Answer 13

No threshold; probability dose related; higher dose = higher probability (e.g. cancer, hereditary effects).

Question 14

What is known about hereditary effects of radiation?

Answer 14

Theoretical DNA changes in germ cells; no evidence of this exists in humans.

Question 15

What is the difference between Gray and Sievert?

Answer 15

Gray (Gy) = absorbed dose; Sievert (Sv) = equivalent/effective dose.

Question 16

What is absorbed dose?

Answer 16

Amount of energy deposited in tissue (J kg⁻¹); measured in Gy; deterministic effects begin ~1 Gy.

Question 17

What is equivalent dose?

Answer 17

Absorbed dose × radiation weighting factor (Wr); measured in Sv; accounts for type of radiation

Question 18

What are the key ways to reduce radiation dose?

Answer 18

Time (reduce exposure), Distance, Shielding (lead gloves/goggles/vests).