What hazards are associated with Class 7 radioactive substances?

• A. They do not contaminate environments.
• B. They are only hazardous to the operator's vision.
• C. They are always explosive.
• D. May cause burns and biological effects; can contaminate surroundings.

Answer: (D)

Class 7 substances pose hazards from ionizing radiation that can affect health in multiple ways. External exposure can cause burns to skin and underlying tissues, and radiation can damage eyes and other organs with sufficient dose. Internal exposure occurs if radioactive material is inhaled, ingested, or enters a wound, leading to biological effects throughout the body and increasing cancer risk over time. In addition, these materials can contaminate surfaces and the surrounding environment if released, creating ongoing contamination that requires decontamination and containment measures. That combination of potential burns, systemic biological effects, and environmental contamination is why this option is the best description.

The other statements are not accurate: one suggests there is no environmental contamination, which ignores contamination risks; another narrows hazards to vision only, which is far too limited; and another claims they are always explosive, which misstates the usual hazards of radioactive substances.