Radioactivity

Radiation from the sun, the earth and the atmosphere are all a part of the natural environment. Radioactive decay can occur inside materials like rocks, and plants over long periods of time. It can also take place inside the human body. The importance of radioactive decay lies in the type of information that can gathered about a human body, or a fossil when radiation amounts are measured.

Radioactive Rays

Environmental radiation moves in rays, or waves that contain energy and, in some cases, particles. The sun emits radiation, but there are no radioactive particles within its rays. Radioactive particles form when atoms have been forced to break apart, or have disintegrated (or decayed) on account of age. There are three main types of radiation --alpha particles, beta particles, and gamma rays. Atoms that have a high amount of energy produce alpha particles. Beta particles are electrons that have broken off from their atoms. Gamma rays are actual waves that have no mass or charge.

Isotopes

Once an atom begins to decay, it carries either a negative or positive charge. This type of atom is called an isotope, and is capable of emitting radiation. In the process of decaying, new atoms can form from the particles being emitted by a decaying atom. These new atoms are called radiogenic, or daughter isotopes. Radiogenic isotopes don't emit radiation, but the atom that's decaying does. How an isotope behaves during the decay process determines what kind of information can be learned about the organism its inside.

Radioactive Labeling

The field of nuclear medicine uses radioactive isotopes to track bodily processes, and identify abnormal cell formations. The isotopes used are called radioactive tracers. Tracers are decaying atoms that have been mixed with high concentrations of other unstable atoms. Chemical reactants designed to seek out certain processes within the body are mixed in with the tracer atoms. This mixture is then injected in the body, and photographed by specialized cameras. Chemical reactants designed to target cancer formations will show the areas of the body in which cancer cells are present. In many cases, the use of radioactive tracers can replace the need for exploratory surgery.

Carbon Dating

Within the geosciences, radioactive isotopes can be used to determine how old a rock formation, or fossil material is. This process is called carbon dating. Carbon dating works by measuring the carbon isotopes that are produced by decayed materials. Isotopes, in general, have a certain amount of time before they stop emitting radiation. Carbon dating works by measuring an isotope's half-life, which is the amount of time it takes for half of the original atom to convert into radioactive material. Geoscientists can measure the amount of radioactive and radiogenic isotopes present to determine the age of a fossil.

Living Organisms

The effects of radioactive decay on living organisms (like the human body) can vary depending on the degree of radiation involved. And while low dosage amounts like those encountered in nature are not harmful, high dosage amounts can cause considerable damage in human tissue. When moderate to high doses come into contact with cell molecules, free ions can become lodged in the tissue. and create free radical materials inside the cells. The presence of free radicals can damage or alter DNA processes within a cell, which can cause cancer, birth defects, and in the most severe cases, death.


Because they are the simplest living organisms and they lack characteristics that eukaryote organisms possess, such as membrane bound organelles and the ability to photosynthesize. They also have relatively small genomes (DNA) and typically have few genes. Not to mention, they are unicellular.