Vomiting is observed within a few hours after radiation exposure, but its cause is unknown. Diarrhea occurs due to damage in the cells that maintain intestinal integrity. Reduction in the number of blood cells results from death of the hematopoietic stem cells in the bone marrow. Bleeding ensues because the blood platelets that coagulate the blood are generated from those hematopoietic stem cells and decline in number with the death of those cells.
Hair is lost due to damage to hair-root cells.
Temporary sterility occurs in men from damage to sperm-generating cells that results in a critical reduction in the number of sperm cells. Clouding in the lens of the eye is the result of damage in cells covering the anterior crystalline lens. These symptoms, with the exception of vomiting, are closely related to cell division because repeatedly dividing cells, eg, bone marrow and intestinal lining, are more sensitive to radiation than nondividing cells, eg, muscle and nerve. If the radiation dose is low, not all of these symptoms necessarily occur. Conversely, a person may die due to bone marrow disorder in one to two months after exposure if the radiation dose is high, or due to intestinal disorder in ten to twenty days after radiation exposure if the dose is extremely high.