Benefits & Dangers of

Radioisotopes

Dating (not that kind)Dating (not that kind)C-14 used to date organic C-14 used to date organic (previously living) (previously living) materialsmaterials

Living organisms incorporate C-14 into their Living organisms incorporate C-14 into their structure, along with C-12 structure, along with C-12

C-14 decays with known half-life (5730 yrs)C-14 decays with known half-life (5730 yrs) 14 14

66C C 14 14 77N + N + 0 0

-1-1

figure out how many half-lives occurred since died: figure out how many half-lives occurred since died: compare amounts C-14 & C-12compare amounts C-14 & C-12

ROCKSROCKS

U-238 decays to Pb-206U-238 decays to Pb-206 (through many (through many decay steps)decay steps)

Over time, amount U-238 Over time, amount U-238 as amount Pb- as amount Pb-206 206 – use use ratio of U-238 to Pb-206 to date rocksratio of U-238 to Pb-206 to date rocks

Chemical TracersChemical Tracers

Can detect radioactive materials and their Can detect radioactive materials and their decay productsdecay products

Tracer = any radioisotope used to follow Tracer = any radioisotope used to follow path of substance in systempath of substance in system– P-31:P-31: determine P uptake in plants determine P uptake in plants– C-14: C-14: map C in metabolic processesmap C in metabolic processes– C-14C-14: map organic molecules; figure out : map organic molecules; figure out

reaction mechanismsreaction mechanisms

Industrial ApplicationsIndustrial Applications

Kill bacteria and spores in food and mailKill bacteria and spores in food and mail

Medical UsesMedical Uses

Use Use radioisotopes with radioisotopes with shortshort half-lives half-lives– quickly eliminated from bodyquickly eliminated from body

– Tracers used for medical diagnosis & Tracers used for medical diagnosis & treatment of cancerstreatment of cancers

I-131I-131: Diagnosis & treatment of : Diagnosis & treatment of thyroidthyroid disorders disorders

Co-60Co-60: gamma emitter: gamma emitter– use: kill use: kill cancercancerous tumorsous tumors

Co-60 and Cs-137Co-60 and Cs-137 – use: destroy use: destroy anthraxanthrax bacilli bacilli

Co-60Co-60 – use: kill use: kill bacteria in foodsbacteria in foods

Tc-99: Tc-99: treatment of treatment of brain cancersbrain cancers

Power PlantsPower Plants

Use: fuel source to generate electricityUse: fuel source to generate electricity

No contributions to greenhouse gasesNo contributions to greenhouse gases

No mercury contamination of atmosphereNo mercury contamination of atmosphere

Radiation RisksRadiation Risks

Can Can damage normal tissuedamage normal tissue

High doses can causeHigh doses can cause illness & death illness & death

Can cause Can cause mutations in DNAmutations in DNA

Disposal of wasteDisposal of waste is is difficultdifficult– Fuel rods are mix of many substancesFuel rods are mix of many substances– Storage & transportation both problematicStorage & transportation both problematic