What occurs when photons are absorbed into cells leading to toxin production that damages the cell?

When photons are absorbed into cells, particularly through ionizing radiation, it can lead to a process described by the indirect theory. This theory posits that the damage to the cell does not occur directly from the radiation itself but through the ionization of water molecules within the cell, leading to the production of free radicals. These free radicals are highly reactive and can cause significant damage to cellular structures, including DNA, proteins, and membranes. This damage can result in cellular dysfunction and, ultimately, cell death.

The indirect theory is crucial in understanding the biological effects of radiation because it highlights that the molecular effects of radiation are not solely due to direct interactions with cellular components but also due to secondary reactions initiated by the radiation energy absorbed by water, which makes up a large part of the cell. This explains the complex nature of radiation injury, as damage can propagate and affect multiple cellular pathways.