Arsenic , chromium , iron , and nickel may be associated with the production of reactive oxygen species , nickel may also be linked to DNA hypermethylation and histone deacetylation , while cadmium may inhibit DNA mismatch repair .
Arsenic , chromium , iron , and nickel may be associated with the production of reactive oxygen species , and some of these may also alter the fidelity of DNA replication . 
 Nickel may also be linked to DNA hypermethylation and histone deacetylation , while cadmium may inhibit DNA mismatch repair .