Aflatoxin is a byproduct of mold that can cause DNA damage. With prolonged exposure to aflatoxin, cells accumulate DNA mutations and thus are at increased risk of developing into cancer cells.
A lot is known about the mechanisms of activation and action of aflatoxin. It forms a reactive epoxide intermediate, which then forms a covalent bond to the N7 atom of guanine in site-specific sequences within critical target genes leading to mutations, altered function, loss of function of those genes. p53 is a major target for aflatoxin.
Aflatoxin is probably the best example of a carcinogen, a human carcinogen that targets p53. There are multiple hot spots in the p53 gene targeted by different types of carcinogens. Aflatoxin targets a guanine in codon 249 in the p53 gene.