What is the main risk associated with exposure to alpha particles?

The primary risk associated with exposure to alpha particles lies in their ability to cause significant damage when ingested or inhaled. Alpha particles are heavy and carry a positive charge, which means they are not very penetrating and can be stopped by a sheet of paper or even the outer layer of human skin. However, when alpha-emitting materials are taken into the body through ingestion or inhalation, they can pose a severe health risk.

Once inside the body, alpha particles can interact with biological tissues, leading to ionization that can cause cellular damage, DNA mutations, and even cancer. This internal exposure is particularly hazardous because the alpha particles can cause localized damage at close range to sensitive tissues, significantly increasing the risk of adverse health effects compared to external exposure, where they cannot penetrate very far.

Options that suggest alpha particles are harmless unless directly exposed to the skin or that they are only dangerous in high-energy states overlook the crucial aspect of internal contamination. Furthermore, while alpha particles are easily deflected by air, this characteristic does not diminish their risk once they enter the body. Understanding the specific risks of alpha particle exposure is essential in radiation safety and health physics.