Personal Use of Hair Dye and the Risk of Certain Subtypes of Non-Hodgkin Lymphoma

Yawei Zhang; Silvia De Sanjose; Paige M. Bracci; Lindsay M. Morton; Rong Wang; Paul Brennan; Patricia Hartge; Paolo Boffetta; Nikolaus Becker; Marc Maynadie; Lenka Foretova; Pierluigi Cocco; Anthony Staines; Theodore Holford; Elizabeth A. Holly; Alexandra Nieters; Yolanda Benavente; Leslie Bernstein; Shelia Hoar Zahm; Tongzhang Zheng

Disclosures

Am J Epidemiol. 2008;167(11):1321-1331. 

In This Article

Abstract and Introduction

Personal use of hair dye has been inconsistently linked to risk of non-Hodgkin lymphoma (NHL), perhaps because of small samples or a lack of detailed information on personal hair-dye use in previous studies. This study included 4,461 NHL cases and 5,799 controls from the International Lymphoma Epidemiology Consortium 1988-2003. Increased risk of NHL (odds ratio (OR) = 1.3, 95% confidence interval (CI): 1.1, 1.4) associated with hair-dye use was observed among women who began using hair dye before 1980. Analyses by NHL subtype showed increased risk for follicular lymphoma (FL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) but not for other NHL subtypes. The increased risks of FL (OR = 1.4, 95% CI: 1.1, 1.9) and CLL/SLL (OR = 1.5, 95% CI: 1.1, 2.0) were mainly observed among women who started using hair dyes before 1980. For women who began using hair dye in 1980 or afterward, increased FL risk was limited to users of dark-colored dyes (OR = 1.5, 95% CI: 1.1, 2.0). These results indicate that personal hair-dye use may play a role in risks of FL and CLL/SLL in women who started use before 1980 and that increased risk of FL among women who started use during or after 1980 cannot be excluded.

The incidence of non-Hodgkin lymphoma (NHL) has been increasing worldwide during the past several decades.[1,2] A recent study showed continuing increases in several major subtypes of NHL, including diffuse large B-cell lymphoma and follicular lymphoma, especially among older persons.[3] Although severe immunosuppression resulting from acquired or congenital conditions, organ transplants, medical treatments, or viral infections is an established risk factor for NHL,[4] it explains only a small proportion of NHL cases. Thus, the etiology of NHL is largely unknown, and presently there are few specific interventions to reduce risk of the disease.

Personal use of hair dye has been suggested as a risk factor for NHL. As a modifiable exposure, the role of hair dye in NHL is of particular interest because of the potential opportunity for prevention. It is estimated that sales of hair-color products worldwide total approximately $12 billion per year and that up to 50 percent of the adult population of high-resource countries uses hair colorants.[5] Hair-coloring products include permanent, semipermanent, and temporary dyes that vary by chemical formulation and are distinguished mainly by how long they last and whether they penetrate the hair shaft. Permanent dyes represent approximately 80 percent of the hair-color market.[5] Some compounds in hair dyes have been reported to be mutagenic or carcinogenic in bioassay systems.[6] Many oxidative dye products were reformulated in the early 1980s to eliminate ingredients that produced tumors in experimental bioassay studies. Although it is unclear whether the current compounds have carcinogenic effects or can affect overall immune response, paraphenylenediamine (PPD), a major arylamine currently used in most hair dyes, has been suggested as a putative carcinogen.[7] In addition, it has been found that many permanent hair dyes are contaminated with 4-aminobiphenyl, a recognized human carcinogen.[8]

During the past two decades, the general public and the scientific community have shown great interest in the potential health impact of personal hair dyes. Epidemiologic studies have been conducted to investigate the relation between hair-dye use and human cancer risk, including risk of NHL.[9,10,11,12,13,14,15,16,17,18,19] The reported results have been inconsistent, perhaps because of methodological limitations, including recall bias, limited detailed information about lifetime hair-dye use, and small samples. Three recent studies from the United States and one from Europe suggested that it might be necessary to investigate the relation between hair-dye use and NHL risk by dye color and time period of use, separating persons who started using hair dyes before 1980 from those who started using them later, when hair-dye formulations underwent significant modification.[14,17,19,20]

In this analysis, we pooled original data from four previously published case-control studies[14,17,19,20] that are part of the International Lymphoma Epidemiology Consortium (InterLymph) to investigate the relation between personal hair-dye use and risk of NHL in detail. Each study collected detailed information on hair-dye use (including duration of use, total number of applications, dates of use, and type and color of dye used). In addition, NHL was classified by histologic subtype. With a total of 10,260 study participants (4,461 NHL cases and 5,799 controls), this InterLymph-based study had greater statistical power than previous studies to evaluate the relation between personal use of hair dyes and NHL risk, particularly for analyses by NHL subtype.

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