3. Common radioactive contaminants of concern (COC)

The contaminants of concern are case by case specific. The more common radioactive contaminants are those arising from concentration of the naturally occurring uranium and thorium series and from man-made produced radionuclides (e.g., ⁶⁰Co, ¹³⁷Cs, ⁹⁰Sr, ²³⁹Pu, ²⁴¹Am, among many others).

Considerable contamination of air, soils, water, vegetation, and structures (e.g., buildings, roads, etc.) has occurred due to:

• The fabrication and testing of nuclear weapons
• Extraction and processing of ores and oil
• Old practices in the use of radionuclides and in waste management
• Accidents involving radionuclides

References:
Technologies for remediation of radioactively contaminated sites (IAEA-TECDOC-1086)