Deaths from hematopoietic and other cancers in relation to permanent hair dye use in a large prospective study (United States).

OBJECTIVES: To assess in a large prospective study whether women who used permanent hair dye, especially dark dye for many years, experienced increased death rates from hematopoietic and other cancers that have been associated with hair dye use in some previous reports.
METHODS: In 1982, 547,586 women provided information on use of permanent hair dye and other lifestyle factors when enrolled in an American Cancer Society (ACS) prospective study. We extended mortality follow-up from 7 to 12 years. Using Cox proportional hazards modeling we compared death rates from hematopoietic and other cancers among women according to their hair dye use at baseline with death rates in unexposed women.
RESULTS: The adjusted death rate from all cancers combined was marginally lower among women who ever used hair dye than nonusers (relative risk [RR] = 0.9; 95% confidence interval [CI] = 0.9-1.0). Mortality from all hematopoietic cancers was marginally higher among users than nonusers (RR = 1.1; CI = 1.0-1.2), and increased with an index that combined duration of use and darker coloration (test of trend p = 0.02). Women who used black or brown dye for 10 or more years experienced somewhat higher death rates from non-Hodgkin's lymphoma and (for black dye only) multiple myeloma. The temporal increase in death rates from non-Hodgkin's lymphoma and multiple myeloma between 1982-88 and 1989-94 was similar for women in our study who never used hair dyes to the increase among all US women.
CONCLUSIONS: If prolonged use of dark permanent hair dyes contributes to death rates from non-Hodgkin's lymphoma and multiple myeloma, then the increase is small and difficult to detect reliably even in large prospective studies. The use of permanent hair dye is unlikely to be a major contributor to the temporal rise in non-Hodgkin's lymphoma and multiple myeloma in the US.