What causes double-stranded breaks in DNA?

Double-stranded breaks (DSBs) in DNA can be caused by certain external factors and endogenous processes. Exposure to external factors such as ionizing radiation and certain chemicals can directly induce DSBs by causing physical damage to the DNA structure. Endogenous processes include DNA replication and DNA repair. Occasionally, errors in the replication process can lead to the formation of DSBs. During DNA repair, DSBS occur when the process of copying DNA during cell division stalls due to unusual DNA shapes, oxidative damage, or abasic sites. Additionally, collisions with other cellular processes can also cause DSBs.