A dose of 200 rad (2 Gy) to the skin can cause which of the following conditions?

• A. Dermatitis
• B. Erythema
• C. Necrosis
• D. Skin cancer

Answer: (B)

A dose of 200 rad (2 Gy) to the skin is typically associated with the development of erythema, which refers to redness of the skin due to increased blood flow in response to injury or irritation. This condition is a common acute effect of radiation exposure that occurs after a certain threshold dose is reached, which can manifest within a few hours to days post-exposure. Erythema is an early indication of skin injury and can be reversible if the dose is within a certain range.

While dermatitis, necrosis, and skin cancer are also potential consequences of radiation exposure, they usually require higher doses or longer-term effects to manifest. Dermatitis may develop as a delayed effect after longer exposure or higher radiation doses, while necrosis typically occurs at much higher doses due to severe tissue damage. Skin cancer rather develops over a prolonged period after cumulative radiation exposure rather than from a single acute dose. Thus, erythema is the expected outcome for the specified dose of 200 rad to the skin.