Genetic damage can occur because of thermal changes, radiation, viruses or the presence of highly reactive chemicals. (magnesium.ca)
When your body is accustomed to seeing certain reactive chemicals / foods on a daily basis, it develops a means to deal with them and expects this daily assault. (pilatesnutritionist.com)
The DNA in all organisms is under constant attack from highly reactive chemicals and radiation, and errors are often made when it is copied. (newscientist.com)