Cobalt-60 uses gamma rays to sterilize medical tools and food without making them radioactive.

Cobalt-60 is a synthetic radioactive isotope produced by exposing natural Cobalt-59 to neutrons in a nuclear reactor. It has a half-life of approximately 5.27 years and decays into stable Nickel-60. During this decay process, it emits two distinct gamma-ray photons with energies of 1.17 and 1.33 MeV. These high-energy photons are powerful enough to break the chemical bonds in the DNA of microorganisms.The process is known as ionizing radiation because it removes electrons from atoms to create ions. When DNA is hit by this radiation, the genetic code of pathogens like Salmonella or E. coli is shattered, preventing them from reproducing. This effectively kills the bacteria and sterilizes the product. Because the energy levels used are below the threshold required to induce nuclear changes in the target material, the items never become radioactive.This technology is regulated by international bodies such as the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO). In the United States, the FDA approved the use of irradiation for various foods starting in the 1960s. Today, over 40 countries use this method to treat more than 500,000 metric tons of food annually. It is also the primary method for sterilizing nearly 40% of all single-use medical devices globally, including syringes and heart valves.