Which statement is true about alpha contamination?

Which statement is true about alpha contamination?

• A. Alpha limits are lower due to high RBE
• B. Alpha RBE is lower than gamma
• C. Alpha is an external exposure hazard only
• D. Alpha contamination does not pose health risks

Answer: (A)

Alpha radiation has very high linear energy transfer, meaning it causes a lot of biological damage for each unit of energy deposited. At the same time, alpha particles don’t travel far in air or through skin, so external exposure is usually low. The real danger from alpha comes when the material is inside the body—inhaled, ingested, or embedded in tissue—where it deposits a large amount of energy in a small area. Because internal exposure from alpha-emitting contamination can be far more damaging than external exposure, the permissible contamination limits are set lower to keep internal doses in check. That’s why this statement is true: alpha contamination limits are lower due to the high RBE (and the strong potential for internal dose). The other ideas don’t fit because alpha’s RBE is not lower than gamma’s; it’s higher. Alpha is not only an external exposure hazard—external exposure from alpha is minimal, but internal exposure from contamination is a major risk. And alpha contamination certainly does pose health risks if it enters the body.

Alpha radiation has very high linear energy transfer, meaning it causes a lot of biological damage for each unit of energy deposited. At the same time, alpha particles don’t travel far in air or through skin, so external exposure is usually low. The real danger from alpha comes when the material is inside the body—inhaled, ingested, or embedded in tissue—where it deposits a large amount of energy in a small area. Because internal exposure from alpha-emitting contamination can be far more damaging than external exposure, the permissible contamination limits are set lower to keep internal doses in check. That’s why this statement is true: alpha contamination limits are lower due to the high RBE (and the strong potential for internal dose).

The other ideas don’t fit because alpha’s RBE is not lower than gamma’s; it’s higher. Alpha is not only an external exposure hazard—external exposure from alpha is minimal, but internal exposure from contamination is a major risk. And alpha contamination certainly does pose health risks if it enters the body.