Modifiers matching tracer:

• luminous,
• soluble,
• radioactive,

Simple categories matching radioactive:

• article,
• isotope,
• substance,
• ore,
• material,
• metal,
• gas,
• substrate,
• source,
• mineral,
• component,
• surface,
• waste,
• decay,
• constituent,
• halogen,
• liquid,
• fluid,
• element,
• tracer,
• poison,
• volatile,
• log,
• solid,
• drug,
• atom,
• particle,
• contaminant,