Participates in the detoxification of a plethora of hydrazine and arylamine drugs. Catalyzes the N- or O-acetylation of various arylamine and heterocyclic amine substrates and is able to bioactivate several known carcinogens. acetyl-CoA + an arylamine = an N-acetylarylamine + CoA N-acetylation polymorphism is determined by a low or high NAT activity in liver and has been implicated in the action and toxicity of amine-containing drugs. Slow acetylation genotypes have been associated with significant lung cancer risk. Candidate risk factor for susceptibility to neural tube defects. The NAT1*10 allele has been associated with increased risk of colon and urinary bladder cancers and with higher levels of N-acetyltransferase activity and DNA adducts in aromatic amine tumor target organs such as colon and urinary bladder (PubMed:7585580). NAT1 was historically considered to be monomorphic in nature but reports of allelic variations at the NAT1 locus suggest that it is a polymorphically expressed enzyme. Belongs to the arylamine N-acetyltransferase family. The allelic variation Ile-149 designated as NAT1*17 is part of the NAT1*11 allelic variation as reported by the nomenclature committee. NAT alleles