Tuesday, May 17, 2011

Radiation in General

It is possible that life on Earth exists thanks to radiation. One of the theories on the origins of life on our planet says that ultraviolet radiation, along with lightning and volcanoes provided the zap of energy needed for non-organic molecules like methane and ammonia, to combine into more complex organic molecules like nucleotides and amino acids (Fortey, 1999). However, where radiation once provided energy to simple molecules, it now disrupted the more complicated bonds within more complex organisms.

The fact is, radiation is present everywhere in our environment. It comes from the soil, the stones, the sun, and from many of the essential technological items we use in our daily lives. The World Nuclear Association reports that the highest level of known background radiation exposure is at the city of Ramsar in northern Iran. The area with the largest populations affected by high natural background radiation are the states of Kerala and Madras in India. Other areas with unusually high background radiation doses can be found in China, Brazil and Australia. However, there has been no evidence that the people living in these areas have a higher incidence of cancer or genetic mutations.

Most people will be familiar with man-made radiation sources like nuclear power plants and medical imaging equipments. Mobile phones, microwave ovens, televisions and laptops are also among the many sources of man-made radiation. Mobile phones, cordless phones, television sets, and radios all emit rediofrequency waves. Laptops that are WiFi-enabled, also emit these waves that enable us to surf the Internet, while microwave ovens make use of microwaves to heat up and cook our food. In this modern, technology-dependent era, we are literally surrounded by all these electromagnetic waves.

The International Agency for Research on Cancer (IARC) has classified radio frequency electromagnetic waves as "possibly carcinogenic to humans". However, generally speaking, radio frequency electromagnetic waves are classified under non-ionizing radiation, along with visible light, infrared and microwaves. This means that the energy emitted by these low-frequency waves is not strong enough to cause electrons to break their bonds within atoms or molecules. These waves are only able to provide more energy to the atoms or molecules they encounter, and cause them to vibrate or move around within their bonds. Therefore, non-ionizing radiation is mostly considered not harmful to living beings, except in certain cases of excessive exposure.

The other more dangerous type of radiation is ionizing radiation. This high-frequency radiation gives out enough energy to break the bonds of electron in atoms or molecules to create charged particles and free radicals. There are three main kinds of ionizing radiation: alpha particles, beta particles, and gamma rays. With high enough dosages, ionizing radiation can cause the breaking up and mutation of our DNA, and disruption of our cellular function. However, the dosage required to cause these conditions is far more than what any average human being is likely to be exposed to, except in highly unusual circumstances, like a nuclear meltdown. In cases like nuclear bombings and large nuclear power plant explosions, the amount of radiation released is usually sufficient to cause instant radiation poisoning.

Reference: Fortey, R. (1999). "Dust to Life". Life: A Natural History of the First Four Billion Years of Life on Earth. New York: Vintage Books, pg 29.

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