Radioactive isotope

Radioactive isotopes (often referred to as radioisotopes or radionuclides) play an important part in the technologies that provide us with food, water and good health. Radioisotopes are unstable radioactive isotopes that either occur naturally or are produced by bombarding small amounts of particular elements with neutrons (usually emitted from a nuclear reactor).

In medicine, radioisotopes are widely used for diagnosis and research. Radioactive chemical tracers emit gamma radiation which provides diagnostic information about a person's anatomy and the functioning of specific organs. Radiotherapy also employs radioisotopes in the treatment of some illnesses, such as cancer. More powerful gamma sources are used to sterilise syringes, bandages and other medical equipment. About one in two people in Western countries is likely to experience the benefits of nuclear medicine in their lifetime, and gamma sterilisation of equipment is almost universal.

In food preservation, radioisotopes are used to inhibit the sprouting of root crops after harvesting, to kill parasites and pests, and to control the ripening of stored fruit and vegetables. Irradiated foodstuffs are accepted by world and national health authorities for human consumption in an increasing number of countries. They include potatoes, onions, dried and fresh fruits, grain and grain products, poultry and some fish. Some prepacked foods can also be irradiated.

In agriculture and animal husbandry, radioisotopes also play an important role. They are used to produce high yielding, disease and weather resistant varieties of crops, to study how fertilisers and insecticides work, and to improve the productivity and health of domestic animals.

Industrially, and in mining, they are used to examine welds, to detect leaks, to study the rate of wear of metals, and for on-stream analysis of a wide range of minerals and fuels.

Most household smoke detectors use radioisotope derived from the plutonium or americium formed in nuclear reactors, saving many lives.

Environmentally, radioisotopes are used to trace and analyse pollutants, to study the movement of surface water, and to measure water runoffs from rain and snow, as well as the flow rates of streams and rivers.

Trace radioisotopes are those that occur in minute amounts in nature either due to inherent rarity or to half-lifes that are significantly shorter than the age of the earth. Synthetic isotopes are not found on earth, and can be created via nuclear reactions.