Hair dye and chemical straightener use and breast cancer risk in a large US population of black and white women

Chemicals of concern in select packaged hair relaxers available on the Kenyan market: an examination of ingredient labels and measurement of pH

Background

There is an emerging interest in the investigation of hair relaxers as important sources of exposure to chemicals of concern (CoCs) and their associated adverse health effects. We focused on documentation of CoCs by examining labels of selected relaxers currently available on the market in Nakuru and Embu Counties, Kenya and measured the pH profiles to ensure compliance with Kenya Bureau of Standards.

Methods

We enrolled 746 women aged 15-50 years in a cross-sectional study, which ascertained participants' sociodemographic characteristics, personal care products use in the last 7-14 days and ever use of hair dyes and chemical relaxers including the brand names of products used. Based on participants' questionnaire responses and product availability at beauty shops and supermarkets, we purchased 22 different relaxer products. The label of each product was reviewed and we recorded relaxer strength, manufacturer and location, listed ingredients, and other claims. To identify CoCs, we cross-checked the list of ingredients against the Campaign for Safe Cosmetics' (CSC) Red List and European Union's prohibited and restricted substances (Annex II and III respectively), Regulation 1223/2009 on cosmetics. The pH profiles of each product were determined using a benchtop pH meter.

Results

Twenty-seven CoCs were documented upon examination with each relaxer listing more than one CoC. Thirteen out of 27 (48.2%) were fragrance chemicals with d-limonene/limonene and linalool, each being listed as an ingredient in 9 products. Fourteen (63.6%) relaxers had undisclosed ingredients listed as 'fragrance' and/or 'parfum'. Six of the identified CoCs are classified as Tier 1 (Do not use for everyone) per CSC Red List while 14.8% (4) are prohibited and 55.6% (15) are restricted substances per EU regulations. The pH values of the relaxers were within Kenya Bureau of Standards required range of 11-13.

Conclusion

These findings create awareness of CoCs listed on labels of selected hair relaxers. This justifies the need for consumer education on potentially harmful chemicals and their associated risks. Further, our findings justify the need for laboratory study to evaluate and quantify CoCs that are listed as well as those that are not listed on the label.

"I am now being who I am and I'm proud of it": Hair related personal and social identity and subjective wellbeing of older Black women in the UK

Hair is an important personal attribute defined by the person's natural hair shape, form and colour as well as by age and health. The hair of Black women has a specific curly texture that has been commonly manipulated to resemble straighter European hair, following centuries of oppressive beauty norms. The biological hair aging also presents challenges to some women due to the traditional social constructs of beauty and the persistent pressure on women to maintain their appearance. This interdisciplinary study explores the evolution of hair management practices of Black women from age-related biological, personal, social and well-being perspectives. A mixed methods approach was adopted, based on an online survey (n = 46) followed by in depth semi-structured interviews (n = 10). A statistically significant shift towards less frequent use of complex hair styles and visits to the hairdressers over a 30-year period was found, but frequency of hair colouring was not impacted. Three main qualitative themes were identified: 1) managing hair greying represented an important age-related negotiation of personal and social identity; 2) curly hair texture remained a strong personal and cultural identity symbol in light of historical dominance of Eurocentric hair beauty standards and hair-based discrimination; and 3) subjective well-being was strengthened by increased confidence in one's personal hair aesthetics and better-informed choices about hair management. Overall, age did not diminish the desire to maintain good hair. Increasing the visibility of older Black women's hair will further support their capacity to negotiate their presence and participation in social and professional contexts and to enhance their subjective well-being.

Systematic Review of the Epidemiology of Hair Relaxer Use and Hormone-Sensitive Reproductive Outcomes Among Black Adult Women in the United States

Hair relaxers are predominantly used by Black women in the United States. It has been recently suggested that exposure to potential endocrine-disrupting compounds from the use of these products may be associated with the development of gynecological and breast cancers and anatomically relevant nonmalignancies. We conducted a systematic literature review using PubMed to identify original studies reporting measures of association between hair relaxer use and relevant adverse outcomes, focusing specifically on Black women in the United States. A total of 1382 studies were initially identified, and after consideration of the exclusion and inclusion criteria, the final set of studies consisted of seven cohort studies and one case-control study. The overall findings suggest that Black women in the United States do not experience an increased risk of breast cancer, ovarian cancer, or uterine cancer due to hair relaxers. One study found a statistically significant association between hair relaxer use and uterine leiomyomata, but there were no other studies identified to support these findings. None of the studies characterized the chemical constituents of hair relaxers. From an epidemiologic perspective, the weight of the evidence does not support the hypothesis that the use of hair relaxers is a risk factor for gynecological and breast cancers in US Black women.

Changing human hair fibre colour and shape from the follicle

INTRODUCTION

Natural hair curvature and colour are genetically determined human traits, that we intentionally change by applying thermal and chemical treatments to the fibre. Presently, those cosmetic methodologies act externally and their recurrent use is quite detrimental to hair fibre quality and even to our health.

OBJECTIVES

This work represents a disruptive concept to modify natural hair colour and curvature. We aim to model the fibre phenotype as it is actively produced in the follicle through the topical delivery of specific bioactive molecules to the scalp.

METHODS

Transcriptome differences between curly and straight hairs were identified by microarray. In scalp samples, the most variable transcripts were mapped by in situ hybridization. Then, by using appropriate cellular models, we screened a chemical library of 1200 generic drugs, searching for molecules that could lead to changes in either fibre colour or curvature. A pilot-scale, single-centre, investigator-initiated, prospective, blind, bilateral (split-scalp) placebo-controlled clinical study with the intervention of cosmetics was conducted to obtain a proof of concept (RNEC n.92938).

RESULTS

We found 85 genes transcribed significantly different between curly and straight hair, not previously associated with this human trait. Next, we mapped some of the most variable genes to the inner root sheath of follicles, reinforcing the role of this cell layer in fibre shape moulding. From the drug library screening, we selected 3 and 4 hits as modulators of melanin synthesis and gene transcription, respectively, to be further tested in 33 volunteers. The intentional specific hair change occurred: 8 of 14 volunteers exhibited colour changes, and 16 of 19 volunteers presented curvature modifications, by the end of the study.

CONCLUSION

The promising results obtained are the first step towards future cosmetics, complementary or alternative to current methodologies, taking hair styling to a new level: changing hair from the inside out.

Evaluation of dermal exposure to phthalates and parabens resulting from the use of hair relaxers

Hair relaxers have been suggested as a source of exposure to parabens and phthalates. However, dermally absorbed doses of these chemicals resulting from consumer use of hair relaxers have yet to be quantified, and results from epidemiological studies have consistently demonstrated that there is no increased risk for hormone-sensitive, reproductive cancers associated with use of hair relaxers among Black women. Therefore, dermal absorption of parabens and phthalates associated with hair relaxer use for several commercially available hair relaxer kits was modeled using IH SkinPerm™. The chemicals detected in the hair relaxer kits included methylparaben (MP), ethylparaben (EP), butylparaben (BP), diethyl phthalate (DEP), bis(2-ethylhexyl) phthalate (DEHP), and the phthalate substitute bis(2-ethylhexyl) adipate (DEHA). The daily absorbed dose ranges (mg/kg/day), standardized over a year of product use, were as follows: 8.64 × 10-5-0.00116 MP, 2.30 × 10-8-3.07 × 10-6 EP, 3.24 × 10-8-4.33 × 10-6 BP, 8.65 × 10-9-1.15 × 10-6 DEP, and 8.94 × 10-7-0.000119 DEHP for Kit #1; 8.44 × 10-5-0.00113 MP and 7.91 × 10-5-0.00106 DEP for Kit #2; and 2.49 × 10-6-3.33 × 10-5 MP, 1.52 × 10-8-2.03 × 10-6 EP, 3.29 × 10-9-4.39 × 10-7 DEP, and 3.11 × 10-6-4.14 × 10-5 DEHA for Kit #3. These absorbed doses were well below applicable health-based guidance values, indicating consumer exposure from product use is not expected to pose a health risk. These results provide valuable information for health risk evaluations for hair relaxer use.

Hair product use and urinary biomarker concentrations of non-persistent endocrine disrupting chemicals among reproductive-aged Black women

BACKGROUND

Studies have shown an association between hair product use and adverse health outcomes. Scientists have hypothesized that exposure to endocrine-disrupting chemicals (EDCs) drives these associations, but few studies have directly evaluated associations between hair product use and biomarkers of EDCs. Even more limited are studies of Black women, who frequently use EDC-containing products (e.g., hair relaxers).

OBJECTIVE

We estimated associations between hair product use and EDC biomarker concentrations.

METHODS

We leveraged cross-sectional data from the Study of Environment, Lifestyle, and Fibroids, a cohort of females aged 23-34 years who self-identified as Black/African American from the Detroit-metropolitan area (USA; n = 425). On structured questionnaires, participants reported their past 24-h and past 12-month use of hair products, including relaxers/straighteners/perms, styling products, moisturizers, oils, and hair food. We quantified urinary concentrations of 19 phthalate/phthalate alternative metabolites, 7 phenols, and 4 parabens using high performance liquid chromatography isotope dilution tandem mass spectrometry. EDC biomarker concentrations were creatinine-adjusted and natural log-transformed. We used multivariable linear regression to estimate mean percent differences in EDC biomarker concentrations and 95% confidence intervals (CIs) associated with hair product use, adjusting for sociodemographic confounders.

RESULTS

Hair product use was associated with greater concentrations of multiple EDC biomarkers. Notably, use of hair products in the previous 24 h (compared with non-use) was associated with 16.2% (95% CI = 0.7%, 35.9%), 35.0% (95% CI = 2.6%, 77.6%), and 32.3% (95% CI = 8.8%, 92.0%) higher concentrations of mono-isobutyl phthalate, methyl paraben, and ethyl paraben, respectively. Use of hair relaxers/straighteners/perms, styling products, moisturizers, oils, and hair food in the past 12 months was also associated with higher concentrations of multiple phthalate, phenol, and paraben biomarkers.

CONCLUSION

Hair product use was associated with higher biomarker concentrations of multiple phthalates, phenols, and parabens. These findings suggest that hair products are potentially important exposure sources for hormonally-active chemicals among Black women.

Frequency of personal care product use among reproductive-aged Black individuals and associations with socio-demographic characteristics

BACKGROUND

Compared to White women, Black women in the United States are more likely to use personal care products (PCPs) with higher concentrations of endocrine-disrupting chemicals (EDCs) and harsher chemical formulations. This may contribute to differential health outcomes in Black women such as increased risk of breast cancer, cardiometabolic outcomes, adverse birth outcomes, and uterine fibroids.

OBJECTIVE

Classify distinct PCP use patterns across multiple types of products and examine how patterns vary by socio-demographic characteristics.

METHODS

The Study of Environment, Lifestyle and Fibroids is a cohort study of reproductive-aged Black individuals living around Detroit, Michigan. Using self-reported data on frequency of PCP collected between 2013-2018, we employed latent class analysis to identify distinct groups of participants with similar PCP use. Socio-demographic characteristics were compared across latent classes.

RESULTS

Among 1562 participants, we identified 6 latent classes: Lower Overall; Higher Nailcare; Higher Skincare; Moderate Overall; Higher Makeup/Haircare/Skincare; Higher Overall. Makeup and nailcare usage were the most predictive for classifying participants into groups. Participants in classes with less frequent use of all PCPs and those with only high use of nailcare products, were more likely to report lower socio-economic status (SES), be current smokers, have a body mass index of ≥35 kg/m2, and have ≥3 births. In comparison, participants in classes with average and more frequent use of PCPs were more likely to report higher SES, be non-smokers, be nulliparous, and have ever used oral contraceptives.

IMPACT STATEMENT

This study is one of the first detailed assessments of PCP usage among a large cohort of young adult Black women that considers multiple product categories including makeup, hair, skin, nail, and vaginal products. Latent class analysis was used to capture complex patterns of PCP use and identify distinct groups of individuals with similar product use. Although the latent classes are specific to this study population, the identified socio-demographic characteristics or behaviors associated with latent classes may inform targeted and impactful exposure reduction strategies in similar populations.

Hair Dye and Relaxer Use among Cisgender Women in Embu and Nakuru Counties, Kenya: Associations with Perceived Risk of Breast Cancer and Other Health Effects

Despite widespread use of hair products globally, little is known about the prevalence and patterns of use in populations outside the United States. As some hair products contain endocrine-disrupting chemicals (EDCs) and EDCs have been linked to breast cancer, which is increasing globally, in this study, we addressed key knowledge gaps about hair product use and practices, and perceptions of use among women in two counties in Kenya. Using community-engaged approaches in Embu and Nakuru, Kenya, we recruited women aged 15-50 years to complete a questionnaire that ascertained hair product use in the last 7-14 days, ever using hair dyes and chemical relaxers, and participants' perceptions or harm around hair product use. In multivariable-adjusted regression models, we evaluated associations between participants' sociodemographic characteristics and perceptions of hair product use in relation to if they have ever used hair dyes and relaxers. In our sample of 746 women (mean age, 30.4 ± 8.1 years), approximately one-third of participants reported ever using permanent and/or semi-permanent hair dyes, with approximately one-fifth reporting current use. Almost 60% reported ever using chemical relaxers, with a little over one-third reporting current use. Increasing age and having an occupation in the sales and service industry were statistically significant predictors of hair dye use (OR 1.04, 95% CI: 1.02-1.06 and OR 2.05, 95% CI: 1.38-3.03, respectively) and relaxer use (OR 1.03, 95% CI: 1.01-1.06 and OR 1.93, 95% CI: 1.30-2.87). On average, participants reported moderate-to-high levels of concern about exposures and general health effects from using hair products, and relatively high levels of perceived risk of breast cancer related to hair product use. However, in contrast to our hypotheses, we observed mixed evidence regarding whether higher levels of perceived risk were associated with lower odds of ever using hair dyes and relaxers. These findings add new knowledge to the extant literature on hair product use among women in Kenya, where breast cancer incidence rates are increasing. Improving the understanding of patterns of use of specific products and their chemical ingredients-which may be hormone disruptors or carcinogens-and exploring the role of environmental health literacy are critical for developing interventions to reduce potentially harmful exposures found in these products.

A systematic review of association between use of hair products and benign and malignant gynecological conditions

Hair products often contain chemicals like para-phenylenediamine (PPD) and endocrine-disrupting chemicals (EDCs); giving rise to concerns about the possible adverse effects such as hormonal disturbances and carcinogenicity. The objective of this systematic review was to evaluate the association between the use of different hair products and benign and malignant gynecological conditions. Studies were identified from three databases including PubMed, Embase, and Scopus, and evaluated in accordance with PRISMA guidelines. The risk of bias was assessed using the Newcastle-Ottawa Scale. A total of 17 English-language studies met the inclusion criteria. Associations of hair relaxer or hair dye use with breast and ovarian cancer were observed in at least one well-designed study, but these findings were not consistent across studies. Further sub-analysis showed 1.08 times (95 % CI: 1.01-1.15) increased risk of breast cancer in females with permanent hair dye use. Chang et al. reported strong association between uterine cancer risk and hair relaxer use (HR 1.8, 95 % CI: 1.12-2.88), with no observed association with hair dye use. Studies conducted by Wise et al. and James-Todd et al. for benign gynecological conditions; including uterine leiomyoma (IRR 1.17, 95 % CI: 1.06-1.30), early onset of menarche (RR 1.4, 95 % CI: 1.1-1.9), and decreased fecundability (FR 0.89, 95 % CI: 0.81-0.98) revealed positive associations with hair relaxer use, but these findings were based on small sample sizes. In summary, the available evidence regarding personal use of hair products and gynecological conditions is insufficient to determine whether a positive association exists.

A Public Health Emergency: Breast Cancer Among Black Communities in the United States

While Black people have a similar incidence of breast cancer compared to White people, they have a 40% increased death rate. Black people are more likely to be diagnosed with aggressive subtypes such as triple-negative breast cancer. However, despite biological factors, systemic racism and social determinants of health create delays in care and barriers to treatment. While genetic testing holds incredible promise for Black people, uptake remains low and results may be challenging to interpret. There is a need for more robust, multidisciplinary, and antiracist interventions to reverse breast cancer-related racial disparities.

Broadening the Environmental Lens to Include Social and Structural Determinants of Women's Health Disparities

BACKGROUND

Due to the physical, metabolic, and hormonal changes before, during, and after pregnancy, women-defined here as people assigned female at birth-are particularly susceptible to environmental insults. Racism, a driving force of social determinants of health, exacerbates this susceptibility by affecting exposure to both chemical and nonchemical stressors to create women's health disparities.

OBJECTIVES

To better understand and address social and structural determinants of women's health disparities, the National Institute of Environmental Health Sciences (NIEHS) hosted a workshop focused on the environmental impacts on women's health disparities and reproductive health in April 2022. This commentary summarizes foundational research and unique insights shared by workshop participants, who emphasized the need to broaden the definition of the environment to include upstream social and structural determinants of health. We also summarize current challenges and recommendations, as discussed by workshop participants, to address women's environmental and reproductive health disparities.

DISCUSSION

The challenges related to women's health equity, as identified by workshop attendees, included developing research approaches to better capture the social and structural environment in both human and animal studies, integrating environmental health principles into clinical care, and implementing more inclusive publishing and funding approaches. Workshop participants discussed recommendations in each of these areas that encourage interdisciplinary collaboration among researchers, clinicians, funders, publishers, and community members. https://doi.org/10.1289/EHP12996.

Use of personal care product mixtures and incident hormone-sensitive cancers in the Sister Study: A U.S.-wide prospective cohort

BACKGROUND

Personal care products (PCPs), a source of endocrine-disrupting chemical exposure, may be associated with the risk of hormone-sensitive cancers. Few studies have investigated associations for PCP use with the incidence of hormone-sensitive cancers or considered the joint effect of multiple correlated PCPs. We examined associations between frequently used, or "everyday", PCPs and incident cancers of the breast, ovary, and uterus with a fucus on the joint effect of multiple product exposure.

METHODS

Sister Study participants (n=49 899) self-reported frequency of use in the year before enrollment (2003-2009) for 41 PCPs. Using five-level frequency categories based on questionnaire options, hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for the associations between multiple PCP use and incident breast, ovarian, and uterine cancer using quantile-based g-computation with Cox proportional hazards regression as the underlying model. Multiple PCP use was examined using groupings (beauty, hygiene, and skincare products) determined by both a priori knowledge and Spearman correlation coefficients for co-occurring product use. Associations between individual PCPs and the three cancers were also examined using Cox proportional hazards models coupling with Benjamini-Hochberg procedure for multiple comparisons.

RESULTS

Over an average of 11.6 years, 4 226 breast, 277 ovarian, and 403 uterine cancer cases were identified. Positive associations were observed between the hygiene mixture and ovarian cancer (HR=1.35, 95%CI=1.00, 1.83) and the beauty mixture with postmenopausal breast cancer (HR=1.08, 95%CI=1.01, 1.16). Additionally, we observed an inverse association between the skincare mixture and breast cancer (HR=0.91, 95%CI=0.83, 0.99). No significant associations were observed for individual products after corrected for multiple comparison.

CONCLUSIONS

Findings from this multi-product, joint-effect approach contribute to the growing body of evidence for associations between PCPs and breast cancer and provides novel information on ovarian and uterine cancer.

Hair relaxer use and risk of uterine cancer in the Black Women's Health Study

BACKGROUND

Chemical hair relaxers, use of which is highly prevalent among Black women in the US, have been inconsistently linked to risk of estrogen-dependent cancers, such as breast cancer, and other reproductive health conditions. Whether hair relaxer use increases risk of uterine cancer is unknown.

METHODS

In the Black Women's Health Study, 44,798 women with an intact uterus who self-identified as Black were followed from 1997, when chemical hair relaxer use was queried, until 2019. Over follow-up, 347 incident uterine cancers were diagnosed. We used multivariable Cox proportional hazards regression models, adjusted for age and other potential confounders, to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of hair relaxer use with risk of uterine cancer.

RESULTS

Compared to women who never used hair relaxers or used them infrequently (<4 years and ≤1-2 times/year), the HR for uterine cancer associated with heavy use (≥15 years and at least 5 times/year) was 1.18 (95% CI: 0.81, 1.71). However, among postmenopausal women, compared to never/light use, the HR for moderate use was 1.60 (95% CI: 1.01, 2.53), the HR for heavy use was 1.64 (1.01, 2.64), and the HR for ≥20 years of use regardless of frequency was 1.71 (1.08, 2.72). Results among premenopausal women were null.

CONCLUSIONS

In this large cohort of Black women, long-term use of chemical hair relaxers was associated with increased risk of uterine cancer among postmenopausal women, but not among premenopausal women. These findings suggest that hair relaxer use may be a potentially modifiable risk factor for uterine cancer.

A Gender Hypothesis of sex disparities in adverse drug events

Pharmacovigilance databases contain larger numbers of adverse drug events (ADEs) that occurred in women compared to men. The cause of this disparity is frequently attributed to sex-linked biological factors. We offer an alternative Gender Hypothesis, positing that gendered social factors are central to the production of aggregate sex disparities in ADE reports. We describe four pathways through which gender may influence observed sex disparities in pharmacovigilance databases: healthcare utilization; bias and discrimination in the clinic; experience of a drug event as adverse; and pre-existing social and structural determinants of health. We then use data from the U.S. FDA Adverse Event Reporting System (FAERS) to explore how the Gender Hypothesis might generate novel predictions and explanations of sex disparities in ADEs in existing widely referenced datasets. Analyzing more than 3 million records of ADEs between 2014 and 2022, we find that patient-reported ADEs show a larger female skew than healthcare provider-reported ADEs and that the sex disparity is markedly smaller for outcomes involving death or hospitalization. We also find that the sex disparity varies greatly across types of ADEs, for example, cosmetically salient ADEs are skewed heavily female and sexual dysfunction ADEs are skewed male. Together, we interpret these findings as providing evidence of the promise of the Gender Hypothesis for identifying intervenable mechanisms and pathways contributing to sex disparities in ADEs. Rigorous application of the Gender Hypothesis to additional datasets and in future research studies could yield new insights into the causes of sex disparities in ADEs.

Beauty Beware: Associations between Perceptions of Harm and Safer Hair-Product-Purchasing Behaviors in a Cross-Sectional Study of Adults Affiliated with a University in the Northeast

(1) Background: Widespread personal care product (PCP) use can expose individuals to endocrine-disrupting chemicals (EDCs) associated with adverse health outcomes. This study investigated the association between harm perceptions and hair-product-purchasing behaviors in adults enrolled in a cross-sectional study. (2) Methods: Respondents rated their agreement with five PCP-related harm statements using a five-point Likert scale. Multivariable-adjusted logistic regression models were used to examine the associations between harm perceptions with hair-product-purchasing behaviors and hair product use (i.e., number of products used). (3) Results: Among 567 respondents (non-Hispanic White, 54.9%; non-Hispanic Black, 9.5%; Hispanic/Latinx, 10.1%; Asian American/Pacific Islander, 20.1%; and multiracial/other, 5.5%), stronger harm perceptions around PCP use were associated with potentially "safer" hair-product-purchasing behaviors. Respondents who strongly agreed that consumers should be concerned about the health effects of PCPs had more than fourfold increased odds of always/usually using healthy product apps (OR 4.10, 95% CI: 2.04-8.26); reading ingredient labels (OR 4.53, 95% CI: 2.99-6.87); and looking for natural, non-toxic, or eco-friendly product labels (OR 4.53, 95% CI: 2.99-6.88) when buying hair products. (4) Conclusions: Promoting environmental health literacy and raising awareness of potential PCP use-related harms might encourage healthier hair product use behaviors.

A Catastrophic Biodiversity Loss in the Environment Is Being Replicated on the Skin Microbiome: Is This a Major Contributor to the Chronic Disease Epidemic?

There has been a catastrophic loss of biodiversity in ecosystems across the world. A similar crisis has been observed in the human gut microbiome, which has been linked to "all human diseases affecting westernized countries". This is of great importance because chronic diseases are the leading cause of death worldwide and make up 90% of America's healthcare costs. Disease development is complex and multifactorial, but there is one part of the body's interlinked ecosystem that is often overlooked in discussions about whole-body health, and that is the skin microbiome. This is despite it being a crucial part of the immune, endocrine, and nervous systems and being continuously exposed to environmental stressors. Here we show that a parallel biodiversity loss of 30-84% has occurred on the skin of people in the developed world compared to our ancestors. Research has shown that dysbiosis of the skin microbiome has been linked to many common skin diseases and, more recently, that it could even play an active role in the development of a growing number of whole-body health problems, such as food allergies, asthma, cardiovascular diseases, and Parkinson's, traditionally thought unrelated to the skin. Damaged skin is now known to induce systemic inflammation, which is involved in many chronic diseases. We highlight that biodiversity loss is not only a common finding in dysbiotic ecosystems but also a type of dysbiosis. As a result, we make the case that biodiversity loss in the skin microbiome is a major contributor to the chronic disease epidemic. The link between biodiversity loss and dysbiosis forms the basis of this paper's focus on the subject. The key to understanding why biodiversity loss creates an unhealthy system could be highlighted by complex physics. We introduce entropy to help understand why biodiversity has been linked with ecosystem health and stability. Meanwhile, we also introduce ecosystems as being governed by "non-linear physics" principles-including chaos theory-which suggests that every individual part of any system is intrinsically linked and implies any disruption to a small part of the system (skin) could have a significant and unknown effect on overall system health (whole-body health). Recognizing the link between ecosystem health and human health allows us to understand how crucial it could be to maintain biodiversity across systems everywhere, from the macro-environment we inhabit right down to our body's microbiome. Further, in-depth research is needed so we can aid in the treatment of chronic diseases and potentially change how we think about our health. With millions of people currently suffering, research to help mitigate the crisis is of vital importance.

Systematic evidence mapping informs a class-based approach to assessing personal care products and pubertal timing

BACKGROUND

Personal care products (PCPs) contain many different compounds and are a source of exposure to endocrine disrupting chemicals (EDCs), including phthalates and phenols. Early-life exposure to EDCs commonly found in PCPs has been linked to earlier onset of puberty.

OBJECTIVE

To characterize the human and animal evidence on the association between puberty-related outcomes and exposure to PCPs and their chemical constituents and, if there is sufficient evidence, identify groups of chemicals and outcomes to support a systematic review for a class-based hazard or risk assessment.

METHODS

We followed the OHAT systematic review framework to characterize the human and animal evidence on the association between puberty-related health outcomes and exposure to PCPs and their chemical constituents.

RESULTS

Ninety-eight human and 299 animal studies that evaluated a total of 96 different chemicals were identified and mapped by key concepts including chemical class, data stream, and puberty-related health outcome. Among these studies, phthalates and phenols were the most well-studied chemical classes. Most of the phthalate and phenol studies examined secondary sex characteristics and changes in estradiol and testosterone levels. Studies evaluating PCP use and other chemical classes (e.g., parabens) had less data.

CONCLUSIONS

This systematic evidence map identified and mapped the published research evaluating the association between exposure to PCPs and their chemical constituents and puberty-related health outcomes. The resulting interactive visualization allows researchers to make evidence-based decisions on the available research by enabling them to search, sort, and filter the literature base of puberty-related studies by key concepts. This map can be used by researchers and regulators to prioritize and target future research and funding to reduce uncertainties and address data gaps. It also provides information to inform a class-based hazard or risk assessment on the association between phthalate and phenol exposures and puberty-related health outcomes.

Assessment of personal care product use and perceptions of use in a sample of US adults affiliated with a university in the Northeast

Evidence supports unequal burdens of chemical exposures from personal care products (PCPs) among some groups, namely femme-identifying and racial and ethnic minorities. In this study, we implemented an online questionnaire to assess PCP purchasing and usage behaviors and perceptions of use among a sample of US adults recruited at a Northeastern university. We collected PCP use across seven product categories (hair, beauty, skincare, perfumes/colognes, feminine hygiene, oral care, other), and behaviors, attitudes, and perceptions of use and safety across sociodemographic factors to evaluate relationships between sociodemographic factors and the total number of products used within the prior 24-48 h using multivariable models. We also summarized participants' perceptions and attitudes. Among 591 adults (20.0% Asian American/Pacific Islander [AAPI], 5.9% Hispanic, 9.6% non-Hispanic Black [NHB], 54.6% non-Hispanic White [NHW], and 9.9% multiracial or other), the average number of PCPs used within the prior 24-48 h was 15.6 ± 7.7. PCP use was greater among females than males (19.0 vs. 7.9, P < 0.01) and varied by race and ethnicity among females. Relative to NHWs, AAPI females used fewer hair products (2.5 vs. 3.1) and more feminine hygiene products (1.5 vs. 1.1), NHB females used more hair products (3.8 vs. 3.1), perfumes (1.0 vs. 0.6), oral care (2.3 vs. 1.9), and feminine hygiene products (1.8 vs. 1.1), and multiracial or other females used more oral care (2.2 vs. 1.9) and feminine hygiene products (1.5 vs. 1.1) (P-values <0.05). Generally, study participants reported moderate concern about exposures and health effects from using PCPs, with few differences by gender, race, and ethnicity. These findings add to the extant literature on PCP use across sociodemographic characteristics. Improving the understanding of patterns of use for specific products and their chemical ingredients is critical for developing interventions to reduce these exposures, especially in vulnerable groups with an unequal burden of exposure.

Plasma metabolomics profiles in Black and White participants of the Adventist Health Study-2 cohort

BACKGROUND

Black Americans suffer disparities in risk for cardiometabolic and other chronic diseases. Findings from the Adventist Health Study-2 (AHS-2) cohort have shown associations of plant-based dietary patterns and healthy lifestyle factors with prevention of such diseases. Hence, it is likely that racial differences in metabolic profiles correlating with disparities in chronic diseases are explained largely by diet and lifestyle, besides social determinants of health.

METHODS

Untargeted plasma metabolomics screening was performed on plasma samples from 350 participants of the AHS-2, including 171 Black and 179 White participants, using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and a global platform of 892 metabolites. Differences in metabolites or biochemical subclasses by race were analyzed using linear regression, considering various models adjusted for known confounders, dietary and/or other lifestyle behaviors, social vulnerability, and psychosocial stress. The Storey permutation approach was used to adjust for false discovery at FDR < 0.05.

RESULTS

Linear regression revealed differential abundance of over 40% of individual metabolites or biochemical subclasses when comparing Black with White participants after adjustment for false discovery (FDR < 0.05), with the vast majority showing lower abundance in Blacks. Associations were not appreciably altered with adjustment for dietary patterns and socioeconomic or psychosocial stress. Metabolite subclasses showing consistently lower abundance in Black participants included various lipids, such as lysophospholipids, phosphatidylethanolamines, monoacylglycerols, diacylglycerols, and long-chain monounsaturated fatty acids, among other subclasses or lipid categories. Among all biochemical subclasses, creatine metabolism exclusively showed higher abundance in Black participants, although among metabolites within this subclass, only creatine showed differential abundance after adjustment for glomerular filtration rate. Notable metabolites in higher abundance in Black participants included methyl and propyl paraben sulfates, piperine metabolites, and a considerable proportion of acetylated amino acids, including many previously found associated with glomerular filtration rate.

CONCLUSIONS

Differences in metabolic profiles were evident when comparing Black and White participants of the AHS-2 cohort. These differences are likely attributed in part to dietary behaviors not adequately explained by dietary pattern covariates, besides other environmental or genetic factors. Alterations in these metabolites and associated subclasses may have implications for the prevention of chronic diseases in Black Americans.

Global epidemiology of breast cancer based on risk factors: a systematic review

BACKGROUND

Numerous reviews of the epidemiology and risk factors for breast cancer have been published previously which heighted different directions of breast cancer.

AIM

The present review examined the likelihood that incidence, prevalence, and particular risk factors might vary by geographic region and possibly by food and cultural practices as well.

METHODS

A systematic review (2017-2022) was conducted following Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, reporting on epidemiological and risk factor reports from different world regions. Medical Subject Heading (MeSH) terms: "Breast neoplasm" "AND" country terms such as "Pakistan/epidemiology", "India/epidemiology", "North America/epidemiology", "South Africa/epidemiology" were used to retrieve 2068 articles from PubMed. After applying inclusion and exclusion terms, 49 papers were selected for systematic review.

RESULTS

Results of selected articles were summarized based on risk factors, world regions and study type. Risk factors were classified into five categories: demographic, genetic and lifestyle risk factors varied among countries. This review article covers a variety of topics, including regions, main findings, and associated risk factors such as genetic factors, and lifestyle. Several studies revealed that lifestyle choices including diet and exercise could affect a person's chance of developing breast cancer. Breast cancer risk has also been linked to genetic variables, including DNA repair gene polymorphisms and mutations in the breast cancer gene (BRCA). It has been found that most of the genetic variability links to the population of Asia while the cause of breast cancer due to lifestyle modifications has been found in American and British people, indicating that demographic, genetic, and, lifestyle risk factors varied among countries.

CONCLUSION

There are many risk factors for breast cancer, which vary in their importance depending on the world region. However, further investigation is required to better comprehend the particular causes of breast cancer in these areas as well as to create efficient prevention and treatment plans that cater to the local population.

Epidemiology and Risk Factors for Breast Cancer: 21st Century Advances, Gaps to Address through Interdisciplinary Science

Research methods to study risk factors and prevention of breast cancer have evolved rapidly. We focus on advances from epidemiologic studies reported over the past two decades addressing scientific discoveries, as well as their clinical and public health translation for breast cancer risk reduction. In addition to reviewing methodology advances such as widespread assessment of mammographic density and Mendelian randomization, we summarize the recent evidence with a focus on the timing of exposure and windows of susceptibility. We summarize the implications of the new evidence for application in risk stratification models and clinical translation to focus prevention-maximizing benefits and minimizing harm. We conclude our review identifying research gaps. These include: pathways for the inverse association of vegetable intake and estrogen receptor (ER)-ve tumors, prepubertal and adolescent diet and risk, early life adiposity reducing lifelong risk, and gaps from changes in habits (e.g., vaping, binge drinking), and environmental exposures.

Toxic effects of Arianor Ebony hair dye on human cells

To evaluate the risks of hair dye exposure, we investigated cellular and molecular effects of Arianor Ebony dye, which is a mixture of azo and anthraquinone dyes, used in the composition of the black color. Cytotoxicity, genotoxicity, and gene expression of relevant molecules of apoptotic and oxidative stress mechanisms were investigated in HepG2 cells exposed to Arianor Ebony. Results showed that the dye did not induce cytotoxicity to exposed cells at a concentration up to 50 µg/mL compared to the negative control. However, genotoxic assays indicated that the dye was able to damage the genetic material at a concentration of 25 µg/mL, with induction factor values of exposed cells two- to five-fold higher than those recorded for the negative control. Moreover, the lowest observed effect concentration was 12.5 µg/mL. For gene expression, relevant changes were observed in cytochrome c and caspase 9, which decreased in cells incubated with the dye in a dose-dependent manner when compared with the negative control. In parallel, the expression of genes for antioxidant enzymes was increased in exposed cells, suggesting the presence of metabolic routes that protect cells against the toxic effect of the dye, avoiding exacerbated cellular death. Results suggested that the dye disrupted cellular homeostasis through mitochondrial dysfunction, which may be hazardous to human health. Thus, further investigations are necessary to deeply understand the mechanisms of action of the dye, considering its toxic potential found in our ex vivo assays.

Use of Chemical Hair Straighteners and Fecundability in a North American Preconception Cohort

Chemical hair straighteners ("relaxers") are used by millions of North Americans, particularly women of color. Hair relaxers may contain endocrine-disrupting compounds, which can harm fertility. We evaluated the association between hair relaxer use and fecundability among 11,274 participants from Pregnancy Study Online (PRESTO), a North American preconception cohort study. During 2014-2022, participants completed a baseline questionnaire in which they reported their history of relaxer use and completed follow-up questionnaires every 8 weeks for 12 months or until pregnancy, whichever came first. We used multivariable-adjusted proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs). Relative to never use, fecundability was lower among current (FR = 0.81, 95% CI: 0.64, 1.03) and former (FR = 0.89, 95% CI: 0.81, 0.98) users of hair relaxers. FRs for first use of hair relaxers at ages <10, 10-19, and ≥20 years were 0.73 (95% CI: 0.55, 0.96), 0.93 (95% CI: 0.83, 1.04), and 0.85 (95% CI: 0.74, 0.98), respectively. Fecundability was lowest among those with longer durations of use (≥10 years vs. never: FR = 0.71, 95% CI: 0.54, 0.91) and more frequent use (≥5 times/year vs. never: FR = 0.82, 95% CI: 0.60, 1.11), but associations were nonmonotonic. In this preconception cohort study, use of chemical hair straighteners was associated with slightly reduced fecundability.

Endocrine-Disrupting Chemicals and Disease Endpoints

Endocrine-disrupting chemicals (EDCs) have significant impacts on biological systems, and have been shown to interfere with physiological systems, especially by disrupting the hormone balance. During the last few decades, EDCs have been shown to affect reproductive, neurological, and metabolic development and function and even stimulate tumor growth. EDC exposure during development can disrupt normal development patterns and alter susceptibility to disease. Many chemicals have endocrine-disrupting properties, including bisphenol A, organochlorines, polybrominated flame retardants, alkylphenols, and phthalates. These compounds have gradually been elucidated as risk factors for many diseases, such as reproductive, neural, and metabolic diseases and cancers. Endocrine disruption has been spread to wildlife and species that are connected to the food chains. Dietary uptake represents an important source of EDC exposure. Although EDCs represent a significant public health concern, the relationship and specific mechanism between EDCs and diseases remain unclear. This review focuses on the disease-EDC relationship and the disease endpoints associated with endocrine disruption for a better understanding of the relationship between EDCs-disease and elucidates the development of new prevention/treatment opportunities and screening methods.

A Comprehensive Review of Mammalian Pigmentation: Paving the Way for Innovative Hair Colour-Changing Cosmetics

The natural colour of hair shafts is formed at the bulb of hair follicles, and it is coupled to the hair growth cycle. Three critical processes must happen for efficient pigmentation: (1) melanosome biogenesis in neural crest-derived melanocytes, (2) the biochemical synthesis of melanins (melanogenesis) inside melanosomes, and (3) the transfer of melanin granules to surrounding pre-cortical keratinocytes for their incorporation into nascent hair fibres. All these steps are under complex genetic control. The array of natural hair colour shades are ascribed to polymorphisms in several pigmentary genes. A myriad of factors acting via autocrine, paracrine, and endocrine mechanisms also contributes for hair colour diversity. Given the enormous social and cosmetic importance attributed to hair colour, hair dyeing is today a common practice. Nonetheless, the adverse effects of the long-term usage of such cosmetic procedures demand the development of new methods for colour change. In this context, case reports of hair lightening, darkening and repigmentation as a side-effect of the therapeutic usage of many drugs substantiate the possibility to tune hair colour by interfering with the biology of follicular pigmentary units. By scrutinizing mammalian pigmentation, this review pinpoints key targetable processes for the development of innovative cosmetics that can safely change the hair colour from the inside out.

p-Phenylenediamine induces epithelial-mesenchymal transition in SV-40 immortalized human urothelial cells via the ERK5/AP-1 signaling

PURPOSE

To investigate whether p-Phenylenediamine (PPD) could triggered EMT inSV-40 immortalized human urothelial cells (SV-HUC-1), and the regulation role of ERK5/AP-1 during this process.

MATERIALS AND METHODS

SV-HUC-1 cells were treated with different concentrations of PPD. MTT assay was employed to detect cell viability. Wound healing and transwell assay were performed to detect migrative and invasive capacity. Western blot and qRT-PCR were utilized for detecting molecular changes. ERK5 specific inhibitor was used to suppress ERK5 signaling.

RESULTS

Migration and invasion capacity of SV-HUC-1cells were enhanced after PPD exposure. Expression of epithelial markers E-cadherin and ZO-1 was decreased and expression of mesenchymal markers N-cadherin and vimentin was increased after being cultured with low concentrations of PPD, indicating that PPD induced EMT in PPD-cultured SV-HUC-1 cells. Meanwhile, PPD triggered activation of ERK5signaling and downstream AP-1 was activated, but no obvious influence of PPD on other sub-families of MAPK was detected. After inhibition of ERK5/AP-1, PPD-induced enhancement of migrative and invasive abilities were attenuated and expression of EMT markers was also reversed.

CONCLUSION

PPD may be a carcinogen, which could induce EMT in SV-40 immortalized human urothelial cells (SV-HUC-1) via activating ERK5/AP-1 signaling.

Chemicals of concern in personal care products used by women of color in three communities of California

BACKGROUND

Personal care products (PCPs) may contain chemicals associated with adverse health effects. Prior studies found differences in product use by race/ethnicity and suggest some women are disproportionately exposed to chemicals of concern (CoCs).

OBJECTIVE

We quantified chemicals linked to cancer, reproductive or developmental harm, or endocrine disruption in PCPs used by women of color.

METHODS

We documented PCPs in stores frequented by Black, Latina, and Vietnamese women in their communities in California and CoCs on ingredient labels of 546 unique hair, skin, makeup, nail, deodorant/perfume, and intimate care products. Community partners chose 31 products for a combined targeted and suspect screen (National Institute of Standards and Technology mass spectral library search) two-dimensional gas chromatography time-of-flight mass spectrometry (GCxGC-TOFMS) analysis to detect chemicals not on ingredient labels.

RESULTS

We found that 65% of labels included CoCs, and 74% of labels had undisclosed ingredients listed as "fragrance." The most prevalent chemicals were parabens, cyclosiloxanes, and formaldehyde releasers. GCxGC-TOFMS found additional CoCs, including fragrances, solvents, preservatives, ultraviolet filters, and contaminants.

SIGNIFICANCE

These findings contribute to awareness of potentially hazardous chemicals in PCPs, can help estimate disparities in chemical exposure, and complement research on health inequities due to chemical exposures from various contributors.

IMPACT STATEMENT

This study is one of the first detailed assessments of chemicals of concern found in various types of PCPs used by several racial/ethnic groups. We found that over half of the 546 products selected by community partners as marketed to and/or used by them contained ingredients linked to cancer, reproductive or developmental harm, or endocrine disruption. Laboratory analysis identified additional chemicals in a subset of products, including unlabeled fragrance chemicals and contaminants. Elucidating exposures to chemicals in PCPs is important for risk assessment and health inequity research.

Use of Straighteners and Other Hair Products and Incident Uterine Cancer

BACKGROUND

Hair products may contain hazardous chemicals with endocrine-disrupting and carcinogenic properties. Previous studies have found hair product use to be associated with a higher risk of hormone-sensitive cancers including breast and ovarian cancer; however, to our knowledge, no previous study has investigated the relationship with uterine cancer.

METHODS

We examined associations between hair product use and incident uterine cancer among 33 947 Sister Study participants aged 35-74 years who had a uterus at enrollment (2003-2009). In baseline questionnaires, participants in this large, racially and ethnically diverse prospective cohort self-reported their use of hair products in the prior 12 months, including hair dyes; straighteners, relaxers, or pressing products; and permanents or body waves. We estimated adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) to quantify associations between hair product use and uterine cancer using Cox proportional hazard models. All statistical tests were 2-sided.

RESULTS

Over an average of 10.9 years of follow-up, 378 uterine cancer cases were identified. Ever vs never use of straightening products in the previous 12 months was associated with higher incident uterine cancer rates (HR = 1.80, 95% CI = 1.12 to 2.88). The association was stronger when comparing frequent use (>4 times in the past 12 months) vs never use (HR = 2.55, 95% CI = 1.46 to 4.45; Ptrend = .002). Use of other hair products, including dyes and permanents or body waves, was not associated with incident uterine cancer.

CONCLUSION

These findings are the first epidemiologic evidence of association between use of straightening products and uterine cancer. More research is warranted to replicate our findings in other settings and to identify specific chemicals driving this observed association.

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.

Evidence-Based Interventions for Reducing Breast Cancer Disparities: What Works and Where the Gaps Are?

The National Cancer Institute (NCI) has established an online repository of evidence-based cancer control programs (EBCCP) and increasingly calls for the usage of these EBCCPs to reduce the cancer burden. To inventory existing EBCCPs and identify remaining gaps, we summarized NCI's EBCCPs relevant to reducing breast cancer risk with an eye towards interventions that address multiple levels of influence in populations facing breast cancer disparities. For each program, the NCI EBCCP repository provides the following expert panel determined summary metrics: (a) program ratings (1-5 scale, 5 best) of research integrity, intervention impact, and dissemination capability, and (b) RE-AIM framework assessment (0-100%) of program reach, effectiveness, adoption, and implementation. We quantified the number of EBCCPs that met the quality criteria of receiving a score of ≥3 for research integrity, intervention impact, and dissemination capability, and receiving a score of ≥50% for available RE-AIM reach, effectiveness, adoption, and implementation. For breast cancer risk reduction, we assessed the presence and quality of EBCCPs related to physical activity (PA), obesity, alcohol, tobacco control in early life, breastfeeding, and environmental chemical exposures. Our review revealed several major gaps in EBCCPs for reducing the breast cancer burden: (1) there are no EBCCPs for key breast cancer risk factors including alcohol, breastfeeding, and environmental chemical exposures; (2) among the EBCPPs that exist for PA, obesity, and tobacco control in early life, only a small fraction (24%, 17% and 31%, respectively) met all the quality criteria (≥3 EBCCP scores and ≥50% RE-AIM scores) and; (3) of those that met the quality criteria, only two PA interventions, one obesity, and no tobacco control interventions addressed multiple levels of influence and were developed in populations facing breast cancer disparities. Thus, developing, evaluating, and disseminating interventions to address important risk factors and reduce breast cancer disparities are needed.

Analysis of Trending Topics in Breast Cancer Articles From an Altmetric Perspective

Background

It is widely known that social media has an impact on politics and the economy. The Altmetric Attention Score (AAS) is a new Web-based metric that was recently developed for use in the scientific field. The objective of this study was to assess which recent studies on the topic of breast cancer received the most attention from the general public.

Methodology

An Altmetric Explorer search was performed on January 7, 2022, to extract the following information: journal name, impact factor (IF), year of publication, article topic, article type, and level of evidence.

Results

The journal that published articles that received the most attention on social media was the New England Journal of Medicine (n = 8). All of the articles were published in journals in the highest IF quartile. The most frequent top three subjects in the top 50 articles were “treatment and management,” “risk factors for breast cancer,” and “breast cancer screening.” The number of articles with a level of evidence of 1, 2, 3, and 4 was 12, 17, 17, and 4, respectively. The correlation between AAS and citation was not significant.

Conclusions

The AAS seems to be a more reliable assessment of public perception of breast cancer. We propose that combining the AAS and traditional metrics may provide a more detailed description of scientific research output.

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.

Impact of two commercially available hair dyes on germination, morpho-physiology, and biochemistry of Cicer arietinum L. and cytotoxicity study on Allium cepa L. root tip

Contamination of agricultural land and surface water by personal care products and pharmaceutical constituents is a potential environmental threat. The active ingredients of personal care products are life-threatening for users. Present work highlighted the efficacy of the different components of two commercially available hair dyes (synthetic and herbal) on germination, morpho-physiological, biochemical parameters of Cicer arietinum, and cytotoxicity study by Allium cepa root tip. Different treatments such as T1 (control), T2 (cream colour rich), T3 (developer) (The ingredients T2 and T3 are from the same hair dye), T4 (an equal mixture of T2 and T3), and T5 (herbal dye) were considered to run this experiment. The results revealed that all the treatments improve germination with respect to control. Moreover, GSI data suggests that T2 showed the highest germination speed and T3 showed the lowest with respect to other treatments. But root lengths are severely affected by the treatments T3 (100% developer of synthetic hair dye), T4 (an equal mixture of T2 (100% cream colour rich) and T3), and T5 (100% herbal hair dye) with respect to control.T2 also showed the highest root tolerance of all treatments other than control. Similarly, one-way ANOVA results revealed that both fresh weight of roots (p ≤ 0.03) and shoots (p ≤ 0.03) are statistically significant among the different treatments. Moreover, both proline and root ion leakage are higher in the treatment T4 and T5 with respect to control, respectively. On the other hand, the cytotoxicity study highlighted that treatments T3 and T4 showed a higher level of aberration and significantly lower mitotic index compared to treatment T5. Therefore, finally, it may be concluded that both individual and combined forms of ingredients of hair dyes are toxic with respect to cell division and overall plant growth and development.

Personal care products: Demographic characteristics and maternal hormones in pregnant women from Puerto Rico

Personal care products (PCPs) refer to a wide variety of items commonly characterized as health or beauty products. PCPs contain a number of ingredients, often including a wide range of endocrine disrupting chemicals such as phthalates and parabens. The present study examines the association between self-reported PCP use and prenatal sex-steroids and thyroid hormones levels in women from Puerto Rico. We recruited pregnant women (n = 1070) through the Puerto Rico PROTECT Cohort and collected blood, demographic and pregnancy-related data at recruitment and subsequent visits. PCP use in the 48-h preceding the blood sample was collected through self-reported questionnaires. Nine hormones (corticotropin-releasing hormone [CRH], sex-hormone binding globulin [SHBG], estriol [E3], progesterone, testosterone, thyroid-stimulating hormone [TSH], total triiodothyronine [T3], total thyroxine [T4], and free thyroxine [fT4]) were measured in maternal serum samples at two points during pregnancy. Linear mixed models with random intercepts were used to examine associations between PCP use and serum hormone levels. Use of cosmetics significantly increased with age, household income and education level (p < 0.01). Use of hair products, such as hair dyes and bleach, relaxers, and mousse, was associated with lower levels of all sex steroid hormones compared to non-use: SHBG (%Δ = -7.1, 95%CI: -12.4,-1.8), E3 (%Δ = -23.2, 95%CI: -32.2,-13.0), progesterone (%Δ = -21.5, 95%CI: -29.4,-12.9) and testosterone (%Δ = -21.5, 95%CI: -33.1,-7.8) adjusted for maternal age, education and pre-pregnancy body mass index. Our findings suggest that household income and education level influence PCP use among pregnant women in this study. Use of certain hair products was associated with lower concentrations of sex steroid hormones. Although there are limitations to questionnaire data, characterizing PCP use is inexpensive and may represent exposure from multiple classes of chemicals, including chemicals that may not specifically appear on product labels and/or have not been tested for endocrine disrupting potential, making it a useful complement to chemical biomarker data.

Hair dye use and prostate cancer risk: A prospective analysis in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort

BACKGROUND

According to the International Agency for Research on Cancer, some hair dye chemicals are considered mutagenic and carcinogenic in humans. One hospital-based study reported a positive association between hair dye use and prostate cancer risk, but no prospective analyses have been conducted.

METHODS

This study investigated the association between hair dye use and prostate cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort, a large, well-characterized cohort of 29,133 male Finnish smokers. Participants completed questionnaires regarding lifestyle, medical, and risk factor information, including the use of hair dye, which was available for 98.8% of the cohort (28,795 men). Prostate cancer cases were identified through linkage with the Finnish Cancer Registry and the Finnish Mortality Register. Hazard ratios (HRs) and confidence intervals (CIs) were estimated via multivariable Cox proportional hazards regression.

RESULTS

During a 28-year period of observation, 2703 incident prostate cancer cases were diagnosed. As reported at the baseline, 75 men used hair dye, and 13 of these men were subsequently diagnosed with prostate cancer. After adjustments for potential confounders, men who used hair dyes experienced substantially higher prostate cancer risk than men who did not (HR, 1.77; 95% CI, 1.03-3.05).

CONCLUSIONS

This first prospective investigation of hair dye use and prostate cancer suggests that personal hair dye use may be related to increased risk. The findings warrant re-examination in other prospective cohorts along with studies evaluating specific hair dyes and possible underlying biological mechanisms.

Potential roles of hsa_circ_000839 and hsa_circ_0005986 in breast cancer

Background

Breast cancer (BC) is one of the leading causes of death among women around the world. Circular RNAs (circRNAs) are a newly discovered group of non‐coding RNAs that their roles are being investigated in BC and other cancer types. In this study, we evaluated the association of hsa_circ_0005986 and hsa_circ_000839 in tumor and adjacent normal tissues of BC patients with their clinicopathological characteristics.

Materials and methods

Total RNA was extracted from tumors and adjacent non‐tumor tissues by the Trizol isolation reagent, and cDNA was synthesized using First Strand cDNA Synthesis Kit (Thermo Scientific). The expression level of hsa_circ_0005986 and hsa_circ_000839 was quantified using RT‐qPCR. Online in silico tools were used for identifying potentially important competing endogenous RNA (ceRNA) networks of these two circRNAs.

Results

The expression level of hsa_circ_0005986 and hsa_circ_000839 was lower in the tumor as compared to adjacent tissues. The expression level of hsa_circ_0005986 in the patients who had used hair dye in the last 5 years was significantly lower. Moreover, a statistically significant negative correlation between body mass index (BMI) and hsa_circ_000839 expression was observed. In silico analysis of the ceRNA network of these circRNAs revealed mRNAs and miRNAs with crucial roles in BC.

Conclusion

Downregulation of hsa_circ_000839 and hsa_circ_0005986 in BC tumors suggests a tumor‐suppressive role for these circRNAs in BC, meriting the need for more experimentations to delineate the exact mechanism of their involvement in BC pathogenesis.

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.

4-Chloro-orthophenylenediamine alters DNA integrity and affects cell survival: inferences from a computational, biophysical/biochemical, microscopic and cell-based study

The deleterious impact of toxic constituents of hair dyes over the human health has gained immense attention in the recent past. Their oncogenicity, mutagenicity, role in protein modification, impact on cellular metabolism has been documented. There is little information on the mechanism of reactivity of hair dye components with the nucleic acids and its implications. This work, therefore, uses computational, biophysical/biochemical, microscopic and cell-based study to analyze the interaction of monocyclic aromatic amine and a hair dye component, 4-chloro-orthophenylenediamine (4-Cl-OPD) with the DNA, its impact on DNA structure and cell survival. The results suggest that 4-Cl-OPD binds with the DNA in minor groove of the duplex involving three base pairs preferentially the G-C residues, induces strand breaks and makes DNA thermally labile through loss of hydrogen bonding/base unstacking. 4-Cl-OPD causes fragmentation of DNA, reduction in size of the molecule, alters B-DNA conformation and disrupts its secondary structure. The modified DNA gives fragmented appearance, shows broken strands and aggregation in ultra-structural analysis. 4-Cl-OPD induces ROS generation in lymphocytes, increases the comet's average tail length and reduces the viability of lymphocytes. This study forms a base for establishing the direct toxicity of 4-Cl-OPD at the molecular and cellular level through direct production of superoxide radicalCommunicated by Ramaswamy H. Sarma.

Use of hair products in relation to ovarian cancer risk

We evaluated whether hair products, which may contain carcinogens and endocrine disruptors that can be absorbed into the bloodstream, are related to ovarian cancer incidence in a prospective cohort. After excluding women with a history of ovarian cancer or bilateral oophorectomy, 40 559 Sister Study participants ages 35-74 at enrollment (2003-2009) were included. Participants completed questionnaires on hair product use, including hair dyes, straighteners/relaxers and permanents/body waves, in the past 12 months. Cox regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between hair products and incident ovarian cancer. We assessed associations stratified by tumor type (serous, non-serous). Over a mean follow-up of 10 years, 241 women were diagnosed with ovarian cancer. Ever use of any of the examined hair products during the past year was not associated with ovarian cancer risk. However, frequent use (>4 times/year) of straighteners/relaxers or pressing products in the past year was associated with an increased risk of ovarian cancer (HR = 2.19, 95% CI: 1.12-4.27). Ever use of permanent hair dye was positively associated with non-serous (HR = 1.94, 95% CI 1.12-3.37), but inversely associated with serous (HR = 0.65, 95% CI: 0.43-0.99) tumors (p-for-heterogeneity = 0.002). Our novel findings suggest that frequent use of hair straighteners/relaxers or pressing products, which are primarily used by African American/Black women, and possibly permanent hair dye, may be associated with the occurrence of ovarian cancers.

Endocrine disrupting chemical-associated hair product use during pregnancy and gestational age at delivery: a pilot study

BACKGROUND

Prenatal endocrine disrupting chemical (EDC) exposure has been associated with increased risk of preterm birth. Non-Hispanic Black women have higher incidence of preterm birth compared to other racial/ethnic groups and may be disproportionately exposed to EDCs through EDC-containing hair products. However, research on the use of EDC-associated hair products during pregnancy and risk of preterm birth is lacking. Therefore, the objective of this pilot study was to estimate associations of prenatal hair product use with gestational age at delivery in a Boston, Massachusetts area pregnancy cohort.

METHODS

The study population consisted of a subset of participants enrolled in the Environmental Reproductive and Glucose Outcomes (ERGO) Study between 2018 and 2020. We collected self-reported data on demographics and hair product use using a previously validated questionnaire at four prenatal visits (median: 12, 19, 26, 36 weeks' gestation) and abstracted gestational age at delivery from medical records. We compared gestational age and hair product use by race/ethnicity and used linear regression to estimate covariate-adjusted associations of product use and frequency of use at each study visit with gestational age at delivery. Primary models were adjusted for maternal age at enrollment and delivery method.

RESULTS

Of the 154 study participants, 7% delivered preterm. Non-Hispanic Black participants had lower mean gestational age at delivery compared to non-Hispanic White participants (38.2 vs. 39.2 weeks) and were more likely to report ever and more frequent use of hair products. In regression models, participants reporting daily use of hair oils at visit 4 had lower mean gestational age at delivery compared to non-users (β: -8.3 days; 95% confidence interval: -14.9, -1.6). We did not find evidence of associations at earlier visits or with other products.

CONCLUSIONS

Frequent use of hair oils during late pregnancy may be associated with shorter gestational duration. As hair oils are more commonly used by non-Hispanic Black women and represent potentially modifiable EDC exposure sources, this may have important implications for the known racial disparity in preterm birth.

Hair product use and breast cancer incidence in the Black Women's Health Study

Hair relaxers and leave-in conditioners and oils, commonly used by Black/African American women, may contain estrogens or estrogen-disrupting compounds. Thus, their use may contribute to breast cancer risk. Results of the few previous studies on this topic are inconsistent. We assessed the relation of hair relaxer and leave-in conditioner use to breast cancer incidence in the Black Women's Health Study, a nationwide prospective study of Black women. Among 50 543 women followed from 1997 to 2017, 2311 incident breast cancers occurred. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression for breast cancer overall and by estrogen receptor (ER) status. For heavy use (≥15 years of use for ≥7 times/year) of hair relaxers relative to never/light use (<4 years, no more than 1-2 times/year), the multivariable HR for breast cancer overall was 1.13 (95%CI: 0.96-1.33). Duration, frequency, age at first use and number of scalp burns were not associated with overall breast cancer risk. For heavy use of hair relaxers containing lye, the corresponding HR for ER+ breast cancer was 1.32 (95% CI: 0.97, 1.80); there was no association for non-lye products. There was no association of conditioner use and breast cancer. Results of this study were largely null, but there was some evidence that heavy use of lye-containing hair relaxers may be associated with increased risk of ER+ breast cancer. Consistent results from several studies are needed before it can be concluded that use of certain hair relaxers impacts breast cancer development.

Personal care product use among diverse women in California: Taking Stock Study

BACKGROUND

Personal care product use may contribute to elevated body burdens of consumer product chemicals among women of color; however, racial/ethnic differences in product use has been understudied. Community-engaged research can support the recruitment of diverse participants.

OBJECTIVE

To document personal care product use among a diverse group of women (aged 18-34 years) living in California.

METHODS

Through a community-academic partnership, we surveyed 357 women in California about product use information for 54 cosmetic, hair, menstrual/intimate care, and leave-on and rinse-off personal care products. We compared type and frequency of product use among Black, Hispanic/Latinx, Asian, and White women. We also summarized use of scented products and reasons women select products.

RESULTS

Women reported using a median of 8 products daily, with some women reporting up to 30 products daily. Hispanic/Latinx and Asian women used more cosmetics, and Black women used more hair and menstrual/intimate products than other women. Of the 54 products compared, there were significant differences in use by race/ethnicity for 28 products, with the largest number of significant differences between Black and White women.

SIGNIFICANCE

There is growing information on chemical exposures from personal care products and consequent adverse health effects, with implications for health disparities. Yet, there remains limited information on the range and types of products used by diverse racial/ethnic communities. This study helps close an important gap on product use inventories that can enable more informed public health interventions to limit exposures from personal care products.

Hormonal activity in commonly used Black hair care products: evaluating hormone disruption as a plausible contribution to health disparities

BACKGROUND

Certain types of hair products are more commonly used by Black women. Studies show hair products contain several endocrine-disrupting chemicals that are associated with adverse health outcomes. As chemical mixtures of endocrine disruptors, hair products may be hormonally active, but this remains unclear.

OBJECTIVE

To assess the hormonal activity of commonly used Black hair products.

METHODS

We identified six commonly used hair products (used by >10% of the population) from the Greater New York Hair Products Study. We used reporter gene assays (RGAs) incorporating natural steroid receptors to evaluate estrogenic, androgenic, progestogenic, and glucocorticoid hormonal bioactivity employing an extraction method using bond elution prior to RGA assessment at dilutions from 50 to 500.

RESULTS

All products displayed hormonal activity, varying in the amount and effect. Three samples showed estrogen agonist properties at levels from 12.5 to 20 ng/g estradiol equivalent concentrations All but one sample showed androgen antagonist properties at levels from 20 to 25 ng/g androgen equivalent concentrations. Four samples showed antagonistic and agonistic properties to progesterone and glucocorticoid.

SIGNIFICANCE

Hair products commonly used by Black women showed hormonal activity. Given their frequent use, exposure to hormonally active products could have implications for health outcomes and contribute to reproductive and metabolic health disparities.

Adolescent use of hair dyes, straighteners and perms in relation to breast cancer risk

Hair products can contain hormonally active and carcinogenic compounds. Adolescence may be a period of enhanced susceptibility of the breast tissue to exposure to chemicals. We therefore evaluated associations between adolescent hair product use and breast cancer risk. Sister Study participants (ages 35-74 years) who had completed enrollment questionnaires (2003-2009) on use of hair dyes, straighteners/relaxers and perms at ages 10 to 13 years (N = 47 522) were included. Cox proportional hazards regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (95% CIs) for associations between hair products and incident breast cancer (invasive cancer or ductal carcinoma in situ), with consideration of heterogeneity by menopausal status and race/ethnicity. Over an average of 10 years of follow-up, 3380 cases were diagnosed. Frequent use of straighteners and perms was associated with a higher risk of premenopausal (HR = 2.11, 95% CI: 1.26-3.55 and HR = 1.55, 95% CI: 0.96-2.53, respectively) but not postmenopausal breast cancer (HR = 0.99, 95% CI: 0.76-1.30 and HR = 1.09, 95% CI: 0.89-1.35, respectively). Permanent hair dye use during adolescence was uncommon (<3%) and not associated with breast cancer overall (HR = 0.97, 95% CI: 0.78-1.20), though any permanent dye use was associated with a higher risk among black women (HR = 1.77, 95% CI: 1.01-3.11). Although frequency of use of perms (37% non-Hispanic white vs 9% black) and straighteners (3% non-Hispanic white vs 75% black) varied by race/ethnicity, associations with breast cancer did not. Use of hair products, specifically perms and straighteners, during adolescence may be associated with a higher risk of premenopausal breast cancer.

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.

Heavy is the Head That Wears the Crown: Black Men's Perspective on Harmful Effects of Black Women's Hair Product Use and Breast Cancer Risk

Racial disparities in breast cancer are well-documented, and Black women assume a disproportionate burden of breast cancer mortality. Black women also commonly use hair products containing endocrine disrupting chemicals (EDCs) more often at an increased rate, as compared to other racial/ethnic groups. Emerging findings have reported the use of hair and other personal care products containing EDCs may contribute to breast cancer risk. While some sociocultural perspectives about hair and identity have been explored, the role of beauty expectations upheld by males has not been studied. Through a community-based participatory methodology, we explored perceptions and beliefs held by Black men regarding Black women's hair, chemical exposures in hair products, and breast cancer risk. Focus groups and key informant interviews-among men with and without partners with a history of breast cancer-were used to examine the male perspective regarding the attractiveness of Black hairstyles, opinions of beauty norms, and knowledge of breast cancer risk factors. Interviews were audio-recorded, transcribed, and analyzed guided by grounded theory methods. From the 66 participants interviewed, there was general support for natural hairstyles, which were associated with confidence and self-esteem in women. Men agreed that beauty standards and societal pressures play notable roles in the women's personal behaviors though they mostly lacked knowledge of women's breast cancer risk related to EDCs found in personal care products. Participants suggested a multipronged strategy centered on community education involving social and traditional media campaigns, and the engagement of policy makers in intervention efforts.

Personal use of permanent hair dyes and cancer risk and mortality in US women: prospective cohort study

OBJECTIVE

To evaluate the associations between personal use of permanent hair dyes and cancer risk and mortality.

DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

117 200 women enrolled in the Nurses' Health Study, an ongoing prospective cohort study of female nurses in the United States. The women were free of cancer at baseline, reported information on personal use of permanent hair dyes, and were followed for 36 years.

EXPOSURE

Status, duration, frequency, and integral use (cumulative dose calculated from duration and frequency) of permanent hair dyes. Age at first use and time since first use of permanent hair dyes.

MAIN OUTCOME MEASURES

Associations of personal use of permanent hair dyes with risk of overall cancer and specific cancers, and cancer related death. Age and multivariable adjusted hazard ratios and 95% confidence intervals were estimated by using Cox proportional hazard models.

RESULTS

Ever users of permanent hair dyes had no significant increases in risk of solid cancers (n=20 805, excluding non-melanoma skin cancers; hazard ratio 0.98, 95% confidence interval 0.96 to 1.01) or hematopoietic cancers overall (n=1807; 1.00, 0.91 to 1.10) compared with non-users. Additionally, ever users did not have an increased risk of most specific cancers (cutaneous squamous cell carcinoma, bladder cancer, melanoma, estrogen receptor positive breast cancer, progesterone receptor positive breast cancer, hormone receptor positive breast cancer, brain cancer, colorectal cancer, kidney cancer, lung cancer, and most of the major subclasses and histological subtypes of hematopoietic cancer) or cancer related death (n=4860; 0.96, 0.91 to 1.02). Basal cell carcinoma risk was slightly increased for ever users (n=22 560; 1.05, 1.02 to 1.08). Cumulative dose was positively associated with risk of estrogen receptor negative breast cancer, progesterone receptor negative breast cancer, hormone receptor negative breast cancer, and ovarian cancer. An increased risk of Hodgkin lymphoma was observed only for women with naturally dark hair (based on 70 women, 24 with dark hair), and a higher risk of basal cell carcinoma was observed for women with naturally light hair.

CONCLUSION

No positive association was found between personal use of permanent hair dye and risk of most cancers and cancer related mortality. The increased risk of basal cell carcinoma, breast cancer (estrogen receptor negative, progesterone receptor negative, hormone receptor negative) and ovarian cancer, and the mixed findings in analyses stratified by natural hair color warrant further investigation.

Mimicking Natural Human Hair Pigmentation with Synthetic Melanin

Human hair is naturally colored by melanin pigments, which afford myriad colors from black, to brown, to red depending on the chemical structures and specific blends. In recent decades, synthetic efforts have centered on dopamine oxidation to polydopamine, an effective eumelanin similar to the one found in humans. To date, only a few attempts at polydopamine deposition on human hair have been reported, and their translation to widespread usage and potential commercialization is still hampered by the harsh conditions employed. We reasoned that novel, mild, biocompatible approaches could be developed to establish a metal-free route to tunable, nature-inspired, long-lasting coloration of human hair. Herein, we describe synthetic and formulation routes to achieving this goal and show efficacy on a variety of human hair samples via multiple spectroscopic and imaging techniques. Owing to the mild and inexpensive conditions employed, this novel approach has the potential to replace classical harsh hair dyeing conditions that have raised concerns for several decades due to their potential toxicity.