Use of hair colouring products and breast cancer risk: a case-control study in Connecticut

Patch Testing to Paraphenylenediamine: The North American Contact Dermatitis Group Experience (1994-2018)

Background/Objectives: Paraphenylenediamine (PPD) is an aromatic amine dye that may cause allergic contact dermatitis. This study examines the epidemiology of allergic patch test reactions to PPD. Methods: This retrospective analysis characterizes individuals tested to PPD (1% petrolatum) by the North American Contact Dermatitis Group (1994-2018). Demographics and dermatitis site(s) were compared between PPD-allergic and PPD-negative patients. PPD reactions were analyzed by reaction strength, clinical relevance, occupational relatedness, and source as well as coreactivity with structurally related compounds. Results: Of 54,917 patients tested to PPD, 3095 (5.6%) had an allergic patch test reaction. Compared with PPD-negative patients, PPD-allergic patients had significantly greater odds of age >40 years (odds ratio [OR] 1.55 [95% confidence interval; CI 1.43-1.69]) and female gender (OR 1.52 [95% CI 1.41-1.66]), but lower odds of being White (OR 0.66 [95% CI 0.60-0.71]). The most common primary anatomic sites of dermatitis were face (25.5%), hands (21.9%), and scattered/generalized pattern (15.5%). Over half (55.3%) of PPD reactions were ++ or +++ at the final reading and 60.9% were currently relevant. Common exposure sources included hair dye (73.5%) and clothing/shoes/apparel (3.9%). Occupationally related reactions occurred in 8.3%, most commonly in hairdressers/cosmetologists (72.8%). The most common coreactions were benzocaine (11.3%), N-isopropyl-N'-phenyl-p-phenylenediamine (6.7%), disperse dye mix (6.5%), and black rubber mix (5.1%). Conclusions: The 24-year percentage of allergic reactions to PPD was 5.6%. PPD allergy was associated with female gender and age >40 years. PPD allergic patients were less likely to be White. Allergic reactions were usually clinically relevant and hair dye was the most frequently identified source.

Risk of Carcinogenicity Associated with Synthetic Hair Dyeing Formulations: A Biochemical View on Action Mechanisms, Genetic Variation and Prevention

Article tries to visualize the potential for carcinogenic trigger in humans with a preference for oxidative synthetic of hair dyeing formulations, especially which belong to the category of permanent colours. According to the International Agency for Cancer, hair dyes for personal use are not strictly classified as carcinogen to humans. However, some controversy exists that requires clarification. Some epidemiological studies support the association between the risk of cancer development and personal use of hair dyes (pooled relative risk RR = 1.50. 95% CI: 1.30-1.98). The world-wide sale of hair dyeing cosmetics have exceeded 15 billion dollars by the year 2012 and has maintained an annual growth rate of 8-10%. This raises concerns and need to be addressed. The review article briefly discusses about the different hair dye components based on their chemical nature, permanence, interaction of dye components with different parts of the hair shaft, action mechanisms, health risk assessment, associated challenges and possible alternatives. There appears variability towards the pathological changes incurred in the human system upon the use of synthetic hair formulations. This probably appears due to the presence of interindividual genetic variation of enzymes handling these xenobiotics. The redox mechanism of major hair dye components appears to be involved in the carcinogenic trigger. Most of the hair dye constituents pose serious health issues. However, we do have few better alternatives to prevent the toxicity associated with hair dye constituents without compromising the need of today's fashion statement and expectations of the youth.

Hair Dye Ingredients and Potential Health Risks from Exposure to Hair Dyeing

Given the worldwide popularity of hair dyeing, there is an urgent need to understand the toxicities and risks associated with exposure to chemicals found in hair dye formulations. Hair dyes are categorized as oxidative and nonoxidative in terms of their chemical composition and ingredients. For several decades, the expert panel's Cosmetic Ingredient Review (CIR) has assessed the safety of many of the chemicals used in hair dyes; however, a comprehensive review of hair dye ingredients and the risk of exposure to hair dyeing has not been documented. Herein, we review the safety of the various chemicals in oxidative and nonoxidative hair dyes, toxicities associated with hair dyeing, and the carcinogenic risks related to hair dyeing. While many compounds are considered safe for users at the concentrations in hair dyes, there are conflicting data about a large number of hair dye formulations. The CIR expert panel has ratified a number of coloring ingredients for hair dyes and banned a series of chemicals as carcinogenic to animals and unsafe for this application. The use of these chemicals as raw materials for producing hair dyes may result in the synthesis of other contaminants with potential toxicities and increased risk of carcinogenesis. It is an open question whether personal or occupational hair dyeing increases the risk of cancer; however, in specific subpopulations, a positive association between hair dye use and cancer occurrence has been reported. To address this question, a better understanding of the chemical and mechanistic basis of the reported toxicities of hair dye mixtures and individual hair dye ingredients is needed. It is anticipated that in-depth chemical and systems toxicology studies harnessing modern and emerging techniques can shed light on this public health concern in the future.

Associations of hair dye and relaxer use with breast tumor clinicopathologic features: Findings from the Women's circle of Health Study

BACKGROUND

Building upon our earlier findings of significant associations between hair dye and relaxer use with increased breast cancer risk, we evaluated associations of select characteristics of use with breast tumor clinicopathology.

METHODS

Using multivariable-adjusted models we examined the associations of interest in a case-only study of 2998 women with breast cancer, overall and stratified by race and estrogen receptor (ER) status, addressing multiple comparisons using Bonferroni correction.

RESULTS

Compared to salon application of permanent hair dye, home kit and combination application (both salon and home kit application) were associated with increased odds of poorly differentiated tumors in the overall sample. This association was consistent among Black (home kit: OR 2.22, 95 % CI: 1.21-5.00; combination: OR 2.46, 95 % CI: 1.21-5.00), but not White women, and among ER+ (home kit: OR 1.47, 95 % CI: 0.82-2.63; combination: OR 2.98, 95 % CI: 1.62-5.49) but not ER-cases. Combination application of relaxers was associated with increased odds of tumors >2.0 cm vs. <1.0 cm (OR = 1.82, 95 % CI: 1.23-2.69). Longer duration and earlier use of relaxers and combination application of permanent hair dyes and relaxers were associated with breast tumor features including higher tumor grade and larger tumor size, which often denote more aggressive phenotypes, although the findings did not maintain significance with Bonferroni correction.

CONCLUSIONS

These novel data support reported associations between hair dye and relaxer use with breast cancer, showing for the first time, associations with breast tumor clinicopathologic features. Improved hair product exposure measurement is essential for fully understanding the impact of these environmental exposure with breast cancer and to guide risk reduction strategies in the future.

Hair chemicals may increase breast cancer risk: A meta-analysis of 210319 subjects from 14 studies

BACKGROUND

The association between personal hair dye use and breast cancer risk is currently debated. The aim of this work is to investigate the association between the use of hair care products and breast cancer risk in women.

METHODS

Based on the PRISMA-IPD statement, the PubMed, Embase, Cochrane Library, Web of Science, OVID and Scopus databases were used to identify eligible studies published from inception to 22 April 2020. A pooled odds ratio (OR) with a 95% confidential interval (CI) was calculated to assess this correlation via fixed- or random-effect Mantel-Haenszel models using a heterogeneity Chi2 test with a significance level of p<0.1. All statistical tests were performed using StataSE software (version 12.0).

RESULTS

The analyzed data comprised 14 eligible studies with 210319 unique subjects. The pooled results suggested that there was a significant association between the use of hair dyes and breast cancer occurrence (pooled OR = 1.07; 95% CI, 1.01-1.13). Regarding the individual analysis regarding the different types of hair chemicals, permanent hair dye users (pooled OR = 1.08; 95% CI, 1.03-1.14) and rinse users (pooled OR = 1.17; 95% CI, 1.02-1.35) were both found to have a significantly elevated breast cancer risk compared to natural hair subjects, whereas there was an insignificant relationship between the use of semipermanent hair dyes (pooled OR = 1.09; 95% CI, 0.92-1.28) and straighteners (pooled OR = 1.04; 95% CI, 0.96-1.14) and breast cancer risk. No impact on the overall correlation between hair dyes and breast cancer risk due to race (White vs non-White) (pooled OR = 1.05; 95% CI, 0.86-1.29), timing of use (<10 years vs ≥10 years) (pooled OR = 0.96; 95% CI, 0.85-1.08) or dye color (Darker than natural hair vs Lighter than natural hair) (pooled OR = 0.91; 95% CI, 0.62-1.32) was found.

CONCLUSIONS

Chemicals in hair dyes may play a role in breast carcinogenesis and increase breast cancer risk.

Hair product use and breast cancer risk among African American and White women

Exposures to carcinogens in hair products have been explored as breast cancer risk factors, yielding equivocal findings. We examined hair product use (hair dyes, chemical relaxers and cholesterol or placenta-containing conditioners) among African American (AA) and White women, and explored associations with breast cancer. Multivariable-adjusted models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) to describe the associations of interest among 2280 cases (1508 AA and 772 White) and 2005 controls (1290 AA and 715 White). Among controls, hair dye use was more common among Whites than AAs (58 versus 30%), while relaxer (88 versus 5%) and deep conditioner use (59 versus 6%) was more common among AAs. Among AAs, use of dark hair dye shades was associated with increased breast cancer risk (OR = 1.51, 95% CI: 1.20-1.90) and use of dark shades (OR = 1.72, 95% CI: 1.30-2.26) and higher frequency of use (OR = 1.36, 95% CI: 1.01-1.84) were associated with ER+ disease. Among Whites, relaxer use (OR = 1.74, 95% CI: 1.11-2.74) and dual use of relaxers and hair dyes (OR = 2.40, 95% CI: 1.35-4.27) was associated with breast cancer; use of dark hair dyes was associated with increased ER+ disease (OR = 1.54, 95% CI: 1.01-2.33), and relaxer use was associated with increased ER- disease (OR = 2.56, 95% CI: 1.06-6.16). These novel findings provide support a relationship between the use of some hair products and breast cancer. Further examinations of hair products as important exposures contributing to breast cancer carcinogenesis are necessary.

Hair Coloring, Stress, and Smoking Increase the Risk of Breast Cancer: A Case-Control Study

PURPOSE

Epidemiologic characteristics of breast cancer in Iran are significantly different from those in the West and even other regional countries, but little is known about the related factors.

PATIENTS AND METHODS

A hospital-based case-control study was conducted on 1052 women (526 new cases and 526 controls). Logistic regression was performed to investigate associations of study factors with breast cancer risk.

RESULTS

This study introduced occupation (odds ratio [OR]_{employed/household}, 1.77; 95% confidence interval [CI], 1.15-2.69), marital age (OR_{24-30 y/< 18 y}, 2.13; 95% CI, 1.03-4.40), age at first delivery (OR_{≥ 30 y/< 18 y}, 3.53; 95% CI, 1.73-7.18), parity (OR_{1-2/Nulliparous or never married}, 2.61; 95% CI, 1.13-6.02), birth interval (OR_{30-50 mos/< 18 mos}, 2.38; 95% CI, 1.45-3.89), lifetime breastfeeding (OR_{≥ 42 mos/< 6 mos}, 0.37; 95% CI, 0.18-0.77), and menarche age (year) (OR, 0.87; 95% CI, 0.79-0.96) as significant associates of breast cancer. In addition, body mass index (OR, 1.07; 95% CI, 1.02-1.11) and some health-related behaviors including hair coloring on a regular basis (OR_yes/no, 1.93; 95% CI, 1.41-2.62), smoking (OR_yes/no, 2.02; 95% CI, 1.22-3.34), oral contraceptive usage (OR_ever/never. 1.46; 95% CI, 1.05-2.04), physical inactivity (OR_{inactive/regular activity}, 1.54; 95% CI, 1.39-1.75), past life stress (OR_{often stressful/often calm}, 2.40; 95% CI, 1.62-3.56), and regular bedtime (OR_{often regular/no}, 0.32; 95% CI, 0.19-0.54) were related to a higher risk of breast cancer.

CONCLUSION

This study revealed a significant number of factors that seem to contribute to the risk of breast cancer even more than the other previously introduced factors.

Does Hair Dye Use Increase the Risk of Breast Cancer? A Population-Based Case-Control Study of Finnish Women

INTRODUCTION

Role of hair dyes in the etiology of breast cancer has occasionally raised concern but previous research has concluded with mixed results. Remnants of prohibited aromatic amines have been found in many hair dye products, and elevated levels of DNA-adducts of these amines have been detected from breast epithelial cells of hair dye users. However, the IARC working group has concluded that there is inadequate evidence for carcinogenicity of personal hair dye use and limited evidence in experimental animals for carcinogenicity of hair colorants.

MATERIAL AND METHODS

We investigated whether the use of hair dyes is associated with breast cancer risk in women. The study design was a retrospective population-based case-control study in Finland, with a self-administered questionnaire from 6,567 breast cancer patients, aged 22-60 years and diagnosed in 2000-2007, and their 21,598 matched controls. We report odds ratios (OR) with 95% confidence interval (95% CI) from a conditional logistic regression model applied to the frequency matched sets of cases and controls. Bias-adjusted odds ratios from the sensitivity analysis are also presented.

RESULTS

After adjusting for potential confounders, the odds of breast cancer increased by 23% (OR: 1.23, 95% CI: 1.11-1.36) among women who used hair dyes compared to those who did not. In women born before 1950 an increase of 28% was noted (OR: 1.28, 95% CI: 1.10-1.48). We also observed a significant trend between the OR and cumulative use of hair dyes (P: 0.005). Bias-adjusted odds ratios varied between 1.04 and 2.50.

CONCLUSIONS

Our results suggest that use of hair dyes is associated with breast cancer incidence. The impact on public health may be substantial due to vast popularity of hair coloring in modern societies. It should be noted that regardless of all efforts, a possibility of bias cannot definitively be ruled out and use of a prospective design is warranted. Based on the present results, it may be concluded however that safety of hair dyes in relation to breast cancer cannot yet be fully acknowledged and lack of external safety assessment within the cosmetics industry is of major concern.

Hair dye use and risk of human cancer

Over 50% of the adult population will use hair dyes at some point in their lifetimes. Hair dyes consist of various chemicals and the composition of these chemicals vary by hair dye types. Chemicals p-phenylenediamine and aminophenyl have been suggested as possible carcinogens or mutagens in experimental studies. The scientific community has been interested in this potential public health impact and the results of published epidemiological studies are summarized here. The current evidence provides limited evidences on the association between personal hair dye use and human cancer risk, except for the possibility of hematopoietic cancers and to a lesser extent, bladder cancer. Risk appears to be affected by time period of use and by specific genetic polymorphisms. Future studies should investigate potential gene and environment interaction to assess possible genetic susceptibility. Several methodological issues should also be considered in future studies including completed hair dye use information such as on timing, duration, frequency and type of hair dye product use.

Association between cancer and contact allergy: a linkage study

Background Contact allergy is a prevalent disorder. It is estimated that about 20% of the general population are allergic to one or more of the chemicals that constitute the European baseline patch test panel. While many studies have investigated associations between type I allergic disorders and cancer, few have looked into the association between cancer and contact allergy, a type IV allergy. By linking two clinical databases, the authors investigate the possible association between contact allergy and cancer. Methods Record linkage of two different registers was performed: (1) a tertiary hospital register of dermatitis patients patch tested for contact allergy and (2) a nationwide cancer register (the Danish Cancer Register). After linking the two registers, only cancer subtypes with 40 or more patients registered were included in the analysis. The final associations were evaluated by logistic regression analysis. Results An inverse association between contact allergy and non-melanoma skin- and breast cancer, respectively, was identified in both sexes, and an inverse trend for brain cancer was found in women with contact allergy. Additionally, a positive association between contact allergy and bladder cancer was found. Conclusion The inverse associations support the immunosurveillance hypothesis (ie, individuals with an allergy are less likely to get cancer due to a triggered immune system), while the positive association with bladder cancer could be due to accumulations of chemical metabolites in the bladder. The authors' findings add to the limited knowledge about contact allergy and the risk of cancer.

Personal use of hair dye and cancer risk in a prospective cohort of Chinese women

Although widely studied over the past 40 years, personal use of hair dye generally has not been associated with overall cancer risk. The association between hair dye use and risk of bladder and hematopoietic cancers has been less conclusive. Most hair dye studies have been case-control studies conducted in Caucasian populations. We examined the relationship between personal hair dye use and cancer risk in a prospective cohort of 70,366 Chinese women. After an average of 7 years of follow up, 2437 women were newly diagnosed with cancer by 31 December 2005. Cox proportional hazard models were used to estimate relative risks (RR) and 95% confidence intervals (CI) of cancer risk associated with hair dye use, adjusting for potential confounding factors. Compared with women who reported no hair dye use, ever users had an overall cancer risk of 0.89 (95% CI 0.82, 0.97). No significant association was observed for several common cancers, including cancers of the breast (RR 0.93, 95% CI 0.78, 1.09), lung (RR 0.81, 95% CI 0.62, 1.09), stomach (RR 0.90, 95% CI 0.66, 1.21), and colorectum (RR 1.04, 95% CI 0.84, 1.28). We also found no significant association with most other cancers, including bladder cancer (RR 1.14, 95% CI 0.56, 2.35) and hematopoietic cancers overall (RR 0.89, 95% CI 0.59, 1.35) or their subtypes, including non-Hodgkin lymphoma, multiple myeloma, and leukemia. We generally found no evidence of an association between personal use of hair dye and cancer risk, although our study is limited by small numbers for certain cancer types.

Hair dye use, meat intake, and tobacco exposure and presence of carcinogen-DNA adducts in exfoliated breast ductal epithelial cells

Diet and environmental exposures to aromatic and heterocyclic amines, and polycyclic aromatic hydrocarbons, are thought to be etiologic factors for breast cancer risk. In this study, we chose to quantify the major DNA adduct derived from one member of each of these classes of carcinogens in epithelial cell DNA isolated from human breast milk. Appreciable adducts were detected for each class, namely 2-amino-6-phenylimidazo[4,5-b]pyridine (PhIP), 4-aminobiphenyl (ABP) and benzo[a]pyrene. The effect of several metabolic genotypes on adduct levels were also investigated and higher PhIP and ABP adducts were associated with the rapid NAT2 and/or rapid NAT1 genotypes. The presence of ABP adducts was also significantly associated with the use of hair coloring products (OR=11.2, 95% CI=1.1-109.2) but not tobacco usage. These data indicate that women are exposed to several classes of dietary and environmental carcinogens and that metabolic genotype can be a susceptibility factor.

Personal hair dye use and cancer: a systematic literature review and evaluation of exposure assessment in studies published since 1992

Hair dyes are widely used, and permanent hair dye is the most commonly used type of product. Permanent hair dye colors are formed by an oxidative process involving arylamines, giving rise to concerns about the potential adverse health effects of long-term exposure, especially cancer. A 1993 International Agency for Cancer Research (IARC) review concluded that evidence was inadequate to evaluate the carcinogenicity of personal hair dye use. This systematic review synthesizes the results from studies of personal hair dye use and cancer published since 1993, taking into consideration the quality of exposure assessment. Thirty-one English-language articles published in January 1992-February 2005 that investigated the association between personal hair dye use and cancer were identified through the PubMed search engine. Quality of exposure assessment was rated between 1+ (lowest quality: assessed ever use of hair dyes) and 4+ (highest quality: assessed dye type [permanent/nonpermanent], dye color/shade, frequency and duration of use). Because of the heterogeneity of the exposure assessment across the studies, a formal meta-analysis was not conducted. Associations between personal hair dye use and non-Hodgkin's lymphoma, multiple myeloma, acute leukemia, and bladder cancer were observed in at least one well-designed study with detailed exposure assessment (rated 3+ or 4+), but were not consistently observed across studies. Results for bladder cancer studies suggest that subsets of the population may be genetically susceptible to hair dye exposures, but these findings are based on small subgroups in one well-designed case-control study. Replication of these findings is needed to determine whether the reported associations are real or spurious.