1. C OBALT -60 I SOTOPE Lucy & Diana

2. A T A G LANCE Cobalt-60 have been used as gamma-ray sources to sterilize pests such as fruit flies. The sterilized male fruit flies are then released into an affected area. They will compete for mating with fertile males but produce no offspring, thereby reducing the pest population.

3. C HEMICAL P ROPERTIES OF C OBALT -60 Group 9 Period 4 Transition Metal Melting point 1768.15 K Boiling point 3200.15 K Density (kg m-3) 8800 Atomic number 27 Atomic mass 60 Number of neutrons 33 Natural abundance of Cobalt-60 is 0% * Natural abundance is the measure of the average amount of a given isotope naturally occurring on Earth.

4. P HYSICAL P ROPERTIES OF C OBALT -60 Cobalt (including cobalt-60) is a hard, brittle, gray metal with a bluish tint. It is solid under normal conditions and is generally similar to iron and nickel in its properties. In particular, cobalt can be magnetized.

5. C OBALT -60 H ISTORY In 1735, a Swedish scientist, George Brandt, demonstrated that a blue color common in colored glass was caused by a new element, cobalt. Radioactive cobalt-60 was discovered by Glenn T. Seaborg and John Livingood at the University of California - Berkeley in the late 1930's.

6. W HY IS IT C HOSEN ? It is used as gamma-rays to repel some fruit flies The powerful gamma rays kill bacteria and other pathogens, without damaging the product. After the radiation ceases, the product is not left radioactive. (also called cold pasteurization)

7. H ALF L IFE Cobalt-60 is a radioisotope, which means it has unstable nucleus. The unstable nucleus undergoes decay until it becomes stable. Its decay has a half life of 5.27 years.

8. O THER U SES OF C OBALT -60 As a tracer for cobalt in chemical reactions Sterilization of medical equipment. Radiation source for medical radiotherapy. Radiation source for industrial radiography. Radiation source for leveling devices and thickness gauges. Radiation source for pest insect sterilization. As a radiation source for food irradiation and blood irradiation. As a radiation source for laboratory use.

9. S AFETY After entering a living mammal (such as a human being), some of the 60 Co is excreted in feces. The remainder is taken up by tissues, mainly the liver, kidneys, and bones, where the prolonged exposure to gamma radiation can cause cancer. Over time, the absorbed cobalt is eliminated in urine.

10. The End Thank You for Your Attention