Benefits & Dangers of Radioisotopes

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  14 6 C  14 7 N  figure out how many half-lives occurred since died: compare amounts C-14 & C-12

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

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

Industrial Applications Kill bacteria and spores in food and mail

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

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

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

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