Radiation, Formaldehyde and Process Safety Management
How ionising and non-ionising radiation harm the body and are controlled, the exposure limits and protection for formaldehyde, and how process safety management prevents the release of highly hazardous chemicals.
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11.1 Ionising and Non-Ionising Radiation
Radiation is energy that travels at very high speed as particles or electromagnetic waves. It is either ionising or non-ionising.
| Term | Meaning |
|---|---|
| Ionising radiation | Radiation with enough energy to remove electrons from atoms it passes through, which makes them charged ions. |
| Non-ionising radiation | Radiation that can excite an atom or molecule but cannot remove an electron. |
| Radioactivity | The spontaneous breakdown of an atomic nucleus with the release of energy. |
| Gamma ray | An electromagnetic wave from the nucleus. |
| Dosimetry | Accurate measurement of radiation dose. |
| Contamination | Radioactive material where it is not wanted. |
| Radiosensitivity | How sensitive a cell is to radiation damage. Fast dividing cells, such as those of an unborn child and the digestive tract, are the most sensitive. Nerve, muscle and bone cells are the least sensitive. |
Where ionising radiation is found
- health care: medical and dental X-rays, therapy and sterilisation of equipment
- industrial radiography, to find faults in welds and metal castings
- nuclear reactors and their support facilities
- test instruments, such as thickness gauges for sheet metal, plastic and paper
- research institutes
Ionising radiation comes as waves, such as gamma rays and X-rays, or as particles, such as alpha, beta and neutron radiation.
Where non-ionising radiation is found
Tanning beds, lasers used for entertainment and other purposes, high frequency heaters, microwave dryers and high power broadcasting and radar stations.
Effects
Chronic exposure to ionising radiation, a low level over a long time, raises the chance of serious conditions such as cancer and cataracts. There may be genetic effects, damage to sperm or egg cells that can cause birth defects. A somatic effect eventually makes a cell cancerous, and a hereditary effect is passed to offspring.
Acute exposure to ionising radiation, a high level over a short time, can cause a lower white blood cell count, nausea, vomiting, loss of appetite, reddened skin, diarrhoea, fatigue, hair loss, sterility and bacterial infections. More severe exposure can cause fever, abdominal pain, internal bleeding, infection, shock, convulsions, coma and death.
Non-ionising radiation does not change molecules but heats tissue. The eyes and skin are most affected.
- Microwaves and radio waves can cause local heating that damages tissue, especially tissue with poor temperature control such as the lens of the eye.
- Frequent exposure to ultraviolet radiation inflames the skin and can cause skin cancer or permanent eye damage.
- Infrared radiation over years can slowly and irreversibly cloud the lens of the eye.
- Lasers can damage the eyes and skin, and high power lasers can cause depigmentation, severe burns and damage to organs underneath.
Control
- Engineering controls: time, distance, shielding, ventilation and containment.
- Administrative controls: warning signs, limits on quantities, safe procedures, training and PPE.
A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.