IGCSE Biology

Sunday 26 February 2017

3.13 understand the detrimental effects of excessive exposure of the human body to electromagnetic waves and describe simple protective measures against the risks.

Microwave: internal heating of body tissue 


  • Prolonged exposure to microwave radiation can lead to burns in the body tissue and cataracts. The most vulnerable areas are the eyes. This is because unlike other body parts, there is a small blood flow for the excess heat (from microwave radiation) to be dissipated or carried away. Eventually, cataracts will be formed in the lens of your eyes and will lead to blurry vision.
  • To prevent burns in the body tissue and cataracts metal screens or surfaces that reflect microwaves should be used.


Infrared: skin burns 


  • A large exposure to infrared can cause severe skin burns and eye problems including cataracts, corneal ulcers and retinal burns, as a result of corneal, retinal and lens damage. This is because unlike other body parts, there is a small blood flow for the excess heat carried away. In addition, the skin has a warning mechanism in the form of pain when the temperatures are very high to a point when they start to damage the skin. However, the eye doesn't contain this mechanism making it unable to prevent the damage. 
  • To avoid skin burns and eye problems don't touch or be exposed to a hot object (e.g. molten metals) for long periods of time. If so, use protective clothing (insulator) and opaque eye protection.


Ultraviolet: damage to surface cells and blindness 



  • Overexposure to ultraviolet radiation can result in; erythema (sunburn), which is the increased blood flow caused by the dilatation of blood vessels. Premature ageing of the skin; it is caused by a change in the structure of the dermis. Suppression of the immune system, it causes the immune system that prevents tumour rejection to stop working. Damage to eyes, this includes Corneal damage, cataracts, macular degeneration (central portion of the retina), overtime this lead to blindness. Lastly, skin cancer; ultraviolet radiation damages the genetic material (DNA) in the skin cells. Over time, if there is enough damage cell will start to grow at of control which leads to skin cancer. 
  • To prevent this you will need to cover from Ultraviolet radiation by using long sleeve clothes, hats, sunglasses and apply sun cream in the exposed areas.


Gamma rays: cancer, mutation 



  • Gamma rays are extremely dangerous if you are overexposed. This is because they have enough energy to remove an electron from an atom, creating an ion (by ionisation). This can damage the body’s cell by killing the cells or by causing mutations which will eventually lead to cancer. 
  • To avoid gamma radiation hospitals use lead shielding and specialist who are exposed to gamma radiation in the daily bases wear protective clothing. 

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