Aromatic
amine components in
hair dyes and polymorphisms in genes that encode
enzymes responsible for
hair dye metabolism may be related to
bladder cancer risk. We evaluated the association between
hair dye use and
bladder cancer risk and effect modification by
N-acetyltransferase-1 (NAT1), NAT2,
glutathione S-transferase Mu-1 (GSTM1) and
glutathione S-transferase theta-1 (GSTT1) genotypes in a population-based case-control study of 1193 incident cases and 1418 controls from Maine, Vermont and New Hampshire enrolled between 2001 and 2004. Individuals were interviewed in person using a computer-assisted personal interview to assess
hair dye use and information on potential confounders and effect modifiers. No overall association between age at first use, year of first use, type of product, color, duration or number of applications of
hair dyes and
bladder cancer among women or men was apparent, but increased risks were observed in certain subgroups. Women who used permanent
dyes and had a college degree, a marker of socioeconomic status, had an increased risk of
bladder cancer [odds ratio (OR) = 3.3, 95% confidence interval (CI): 1.2-8.9]. Among these women, we found an increased risk of
bladder cancer among exclusive users of permanent
hair dyes who had NAT2 slow acetylation phenotype (OR = 7.3, 95% CI: 1.6-32.6) compared to never users of
dye with NAT2 rapid/intermediate acetylation phenotype. Although we found no relation between
hair dye use and
bladder cancer risk in women overall, we detected evidence of associations and gene-environment interaction with permanent
hair dye use; however, this was limited to educated women. These results need confirmation with larger numbers, requiring pooling data from multiple studies.