What is a common effect of excessive radiation exposure?

Excessive radiation exposure is primarily associated with a heightened risk of cancer due to the damaging effects radiation can have on cellular structures, particularly DNA. When cells are exposed to high levels of radiation, the DNA can suffer breaks or mutations, which may lead to uncontrolled cell growth and ultimately cancer. This risk is cumulative and is influenced by both the dose and duration of exposure.

The other options listed do not reflect accurate effects of excessive radiation exposure. For instance, increased mental clarity and improved physical endurance are not scientifically supported outcomes of high radiation levels. Additionally, an excessive dose of radiation is more likely to suppress the immune system rather than heighten its response, making the body more vulnerable to infections and diseases. Understanding the implications of radiation exposure is crucial for safety practices in environments where radiation is present.