Gamma rays are harmful to living matter because they penetrate far into the body and damage millions of cells at the same time.
Radiation converts molecules in living cells to ions or free radicals.
These exert their most destructive effect on DNA.
Small radiation doses can kill cells, alter genes, and damage chromosomes.
The repair mechanism is not always perfect.
Incorrect repair of DNA damage can lead to leukemia, birth defects, and many forms of cancer.
Large radiation doses can lead to impairment of organ function and illness.
Death can result from severe damage to key organs such as skin, intestines, bone marrow, lungs, and liver).
Typical damage to DNA includes breaking the hydrogen bonds between bases, base loss, and base change.
It also includes the creation of new cross linkages, single strand breaks, and double strand breaks.
The most serious damage to DNA is a double-strand break.
Unrepaired breaks lead to the re-joining of incorrect fragments.
This can cause mutations, kill cells, and lead to the loss or amplification of chromosomal material.