1. Benefits & Dangers of Radioisotopes

2. Dating (not that kind) C-14 used to date organic (previously living) materials Living organisms incorporate C-14 into their structure, along with C-12 C-14 decays with known half-life (5730 yrs) 14 6 C  14 7 N + 0 -1  14 6 C  14 7 N + 0 -1  figure out how many half-lives occurred since died: compare amounts C-14 & C-12

3. ROCKS U-238 decays to Pb-206 (through many decay steps) Over time, amount U-238  as amount Pb- 206  –use ratio of U-238 to Pb-206 to date rocks

4. Chemical Tracers Can detect radioactive materials and their decay products Tracer = any radioisotope used to follow path of substance in system –P-31: determine P uptake in plants –C-14: map C in metabolic processes –C-14: map organic molecules; figure out reaction mechanisms

5. Industrial Applications Kill bacteria and spores in food and mail

6. Medical Uses Use radioisotopes with short half-lives –quickly eliminated from body –Tracers used for medical diagnosis & treatment of cancers

7. I-131: Diagnosis & treatment of thyroid disorders Co-60: gamma emitter –use: kill cancerous tumors Co-60 and Cs-137 –use: destroy anthrax bacilli Co-60 –use: kill bacteria in foods Tc-99: treatment of brain cancers

8. Power Plants Use: fuel source to generate electricity No contributions to greenhouse gases No mercury contamination of atmosphere

9. Radiation Risks Can damage normal tissue High doses can cause illness & death Can cause mutations in DNA Disposal of waste is difficult –Fuel rods are mix of many substances –Storage & transportation both problematic