Explain Radioactivity and its Problems and Applications?

All radiation, electromagnetic as well as the kind from nuclear decay, takes its toll on living organisms. If the radiation has enough energy it can disrupt the functioning of living cells. This is particularly harmful if the radiation damages the nucleic acid molecules which make up your genetic information. 

We are constantly being exposed to radiation from natural sources. Rocks contain radioactive elements, we are being bombarded by cosmic rays from space and our food and water contain radioactive particles. Additional amounts of radiation come from man-made sources such as testing from nuclear weapons, medical x-rays and nuclear power plants. 

All three types of radiation come in a variety of different energies, but we can make generalizations.  Alpha particles are the least penetrating (they can be blocked by a t-shirt) but because of their large mass, they are the most harmful if they actually get into your system.  Gamma rays are the most penetrating and require several centimeters of lead to stop them.  Beta particles are somewhere in between.  They can be stopped by aluminum foil.    

Using Radioactive Nuclides:

Radioactive elements are easily found because they emit radiation. They can be used as tracers to show what is happening in plants and animals.  A radioactive isotope of a molecule can be substituted for the regular atom used by a specific organ in your body. Doctors can follow the path of that tracer by detecting the movement as it wanders through your body. Areas of high or low radioactivity signal a problem area.

 Radioactive isotopes can also be used to target cancer cells.  If you have a thyroid cancer doctors will often prescribe iodine-131.The iodine accumulates in the gland and the radiation destroys the cancer cells. For other types of cancer, external sources of radiation bombard the cancerous cells to destroy them

Some naturally occurring nuclides can be used in archeological and geological dating. We already mentioned these applications in the section entitled Radioactive Dating.