NAT1 and breast cancer: In addition, the correlation we found between AAs exposure and BC risk is biologically plausible, because AAs are activated in liver and transported by blood proteins to the bladder where, under acidic conditions [45] or, enzymatically by O-acetylation of N-hydroxyarylamine (predominantly by the N-acetyltransferase 1 (NAT1) isozyme), are further activated to the ultimate carcinogen [46].