Which statement best describes the primary way fallout radioisotopes pose a public health risk for humans?

• A. Inhalation of fine particles from the fallout cloud
• B. May cause radiation burns on exposed skin
• C. Have long biological half-lives and concentrate in critical radiosensitive organs
• D. May be ingested in large amounts by consumption of dairy products and foods of plant origin

Answer: (D)

The key idea is how people receive the dose from fallout: the main public health risk comes from radionuclides entering the body through the food chain. After fallout settles, radioactive particles contaminate pastures and crops. Animals that eat that forage pass radionuclides into milk and meat, and plants take up radionuclides from the soil. Because dairy products and many plant-based foods are widely consumed, this food‑borne route can lead to substantial internal radiation doses across a large population, with some radionuclides concentrating in specific organs and remaining in the body longer. Inhalation and external exposure can occur, but they generally contribute less to long-term public health risk compared with ingestion through dairy and plant foods.