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ABC of Safety in the Biological Sciences
RADIATION - IONISING
The presence of charged ions in living tissue can disrupt normal biological processes. Exposure to levels exceeding recommended doses may induce tumour formation or incur genetic damage. The unit of dose equivalent is the sievert (Sv). One sievert of ionising radiation from any source (a, b or g) carries the same risk of genetic change. Recommended limits of exposure110 111 in any 3 month period are contained in TABLE 11.
Ionising radiation can be divided into two classes.112
1. External hazards - sources outside the body. These are controlled by:
- limiting exposure times
- having greatest possible distance between source and worker
- using suitable shields
2. Internal hazards - radioactive substances which enter the body by inhalation, ingestion or absorption. These are controlled by:
- containment of the material - in safe handling techniques
- extreme cleanliness of work area
- using least amount of radioactive material necessary to complete the task.
These substances should only be used by suitably qualified personnel under strict supervision and never pipetted by mouth. Minor spills must be cleaned up quickly. Full protective clothing, comprising a long sleeved laboratory coat or gown, rubber gloves and full face shield must be worn. Areas where a spill has occurred should be monitored using a Geiger counter.
For major spills evacuate the area and re-enter only when expert assistance is available and advice has been received on the type of clothing that should be worn and the potential hazard from the spill.
Treat obvious injuries immediately whilst avoiding the spread of contamination. Wash the affected area with soap and water and wash cuts with fast running water. Irrigate eyes with saline solution or tap water for a minimum of five minutes. Notify the appropriate authorities and monitor the area with a Geiger counter until decontaminated.
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