Objectives: Hair coloring products are widely used and contain components that are mutagenic and carcinogenic. An association between occupational exposure to hair coloring products and hematopoietic cancers has been reported, but the risk for these cancers among users has not been carefully evaluated.
Methods: We conducted a population-based, case-control study with telephone interviews from 385 with telephone interviews from 385 non-Hodgkin's lymphoma cases, 70 Hodgkin's disease cases, 72 multiple myeloma cases, 56 chronic lymphocytic leukemia cases, and 1432 controls.
Results: Among women, use was associated with odds ratios of 1.5 for non-Hodgkin's lymphoma, 1.7 for Hodgkin's disease, 1.8 for multiple myeloma, and 1.0 for chronic lymphocytic leukemia. Risk was higher for permanent hair coloring products than for semi- or nonpermanent products, particularly for dark colors. Long duration and early age of first use tended to increase risk, but the patterns were inconsistent. Use was much less common in men and did not significantly increase risk.
Conclusions: The use of hair coloring products appears to increase the risk of non-Hodgkin's lymphoma. Multiple myeloma and Hodgkin's disease were also associated, although based on far fewer subjects. If these results represent a causal association, use of hair coloring products would account for 35% of non-Hodgkin's lymphoma cases in exposed women and 20% in all women.