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
6C
 14 7N + 0 -1
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 Pb206 
– 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