Localized doses of 7 Gy to the skin can cause _____.

Localized doses of 7 Gy to the skin are associated with permanent hair loss due to the significant impact on hair follicle cells. This dose is high enough to damage the rapidly dividing cells found in hair follicles, which can lead to a condition known as alopecia. Unlike other types of cells that may have the capacity to recover, hair follicle cells typically do not regenerate after such a high dose of radiation, resulting in long-lasting effects like permanent hair loss.

Doses of this magnitude can cause physical changes to the skin, including potential burns and changes to its structure, but these are distinct from the systemic effects that might lead to death or gastrointestinal syndrome, which typically result from much higher doses affecting larger volumes of critical tissues or organs. Death and gastrointestinal syndrome are associated with whole-body doses or localized doses that affect vital organs, not the skin specifically. Thus, the most accurate completion of the statement given the context of 7 Gy localized to the skin is that it can cause permanent hair loss.