West Coast study of childhood brain tumours and maternal use of hair-colouring products

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.

Association between gestational hair dye use and allergies at 3 years old: the Japan environment and Children's study

BACKGROUND

Hair dye use frequently induces allergic contact dermatitis, and on rare occasions induces immunoglobulin E-mediated immediate urticaria, anaphylaxis, and asthma. The effects of hair dye use during pregnancy on offspring have been studied for carcinogenicity, but not for development of allergies. This study aimed to assess the association between hair dye use during pregnancy and allergic disease in children at 3 years old.

METHODS

Data of 77,303 participants from the Japan Environment and Children's Study, which is a prospective birth cohort recruited from January 2011 to March 2014, were used. We examined the associations between using hair dye during pregnancy and allergic diseases (food allergy, asthma, atopic dermatitis and allergic rhinitis) in children after adjustment for covariates by multivariable logistic regression.

RESULTS

Among mothers who were exposed to hair dye during pregnancy, 50.0% were exposed in hair salons, 21.3% had home use, and 9.5% had occupational exposure. The percentages of doctor-diagnosed allergies at 3 years old were 6.3% for food allergies, 7.7% for asthma, 7.3% for atopic dermatitis, and 4.6% for allergic rhinitis. In univariable analyses, hair dye use at home and occupational exposure was significantly associated with asthma respectively (odds ratio [OR] 1.15, 95% CI 1.07-1.24 for at home; OR 1.18, 95% CI 1.08-1.28 for occupational exposure). Hair dye use at home were significantly associated with doctor-diagnosed allergic rhinitis at 3 years old (OR 1.12, 95% CI 1.02-1.22). After adjustment for covariates, these associations for asthma decreased and were no longer significant (aOR 1.06, 95% CI 0.98-1.14 for at home; aOR 1.09, 95% CI 1.00-1.20 for occupational exposure, p = 0.057), also for allergic rhinitis (aOR 1.07, 95% CI 0.97-1.19). Doctor-diagnosed allergic rhinitis at 3 years old was significantly associated with hair dye use at home in the most frequent use group (aOR for quite often versus never 1.78, 95% CI 1.22-2.60).

CONCLUSION

Both home and occupation use of hair dye during pregnancy showed a trend of increased odds of allergic rhinitis and asthma in offspring at 3 years. However, the only association that reached significance was in frequency of use analyses between the highest frequency of home hair dye users and allergic rhinitis.

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.

In Vitro and In Vivo Analysis of the Effects of 3,5-DMA and Its Metabolites in Neural Oxidative Stress and Neurodevelopmental Toxicity

3,5-Dimethylaniline (3,5-DMA), a monocyclic aromatic amine, is widely present in a spectrum of sources including tobacco, dyes, combustion products, and suspended particulates. 3,5-DMA and its metabolites form superoxides, resulting in apoptosis or oncogenesis. Data of a direct effect of 3,5-DMA on the nervous system, especially the developing brain, are lacking. Therefore, we investigated the effects of 3,5-DMA and its metabolites on fetal neurite growth and brain development using in vitro cell cultures of primary cortical neurons to observe whether these compounds caused neuronal cytotoxicity and affected neurite structural development. With increasing concentrations of 3,5-DMA (10, 50, 100, 500, 1000 μM) and its major metabolite 5-dimethylaminophenol (3,5-DMAP) (10, 50, 100, 500, 1000 μM), reactive oxygen species (ROS), cytotoxicity, and DNA damage increased significantly in the cells and dendritic arborization decreased. The addition of 5 mM N-acetylcysteine, an ROS scavenger, reduced ROS in the cells and alleviated the neuronal damage. In vivo studies in Sprague Dawley pregnant rats suggested that exposure to 3,5-DMA (10, 30, 60, 100 mg/kg/day) subcutaneously from GD15 to GD17 led to fetal cerebral cortex thinning. BrdU labeling showed that 3,5-DMA reduced the number and generation of cortical cells. To detect the laminar position of newly generated neurons, cortex layer markers such as Satb2, Ctip2, and Tbr1 were used. 3,5-DMA perturbed the cortical layer distribution in developing fetal rats. In summary, this is the first study to provide evidence for 3,5-DMA and its metabolites causing anomalies of the fetal central nervous system development through ROS production.

Occupational chemical exposures among cosmetologists: risk of reproductive disorders

More research is needed to understand possible occupational reproductive risks for cosmetologists, specifically hairdressers and nail technicians, two occupations that often share workspace and exposure to hair dyes and nail polish. Cosmetologists are predominantly females of reproductive age; thus, they may be at higher risk for the effects of exposure to reproductive toxins. The purpose of this article is to inform nurses and public health professionals about occupational exposures for cosmetologists and discuss interventions to reduce the risks of reproductive disorders among susceptible worker populations.

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.

Representativeness of child controls recruited by random digit dialling

Recruiting control subjects who are representative of the population from which the cases are drawn is a challenge in case-control studies. This paper examines the performance of random digit dialling (RDD) in obtaining a control sample, and the sample's representativeness of the population with respect to socio-economic status. The study subjects were recruited from 2003 to 2006 for a national, population-based case-control study investigating causes of acute lymphoblastic leukaemia (ALL) in children <15 years of age in Australia. Control families' addresses were linked to Australian Bureau of Statistics Census 2006 Collection Districts and thus to Socio-Economic Indexes for Area scores, which are area-based measures of socio-economic status. These scores were compared with those of all collection districts where families lived. We estimate that 55% of eligible families in the RDD sample agreed to participate in the study. Participation was directly related to socio-economic status with those of highest economic status most likely to participate. Completeness of participation in the components of data collection was similarly related to socio-economic status. This evidence of selection according to socio-economic status indicates that there may also be selection with respect to other factors potentially important in the aetiology of ALL.

[Epidemiology of primary brain tumor]

Two main approaches are generally used to study the epidemiology of primary brain tumors. The first approach is to identify risk factors, which may be intrinsic or related to external causes. The second main approach is descriptive. Intrinsic factors potentially affecting risk include genetic predisposition and susceptibility, gender, race, birth weight and allergy. Radiation exposure is the main extrinsic factor affecting risk. A large body of work devoted, among others, to electromagnetic fields and especially cellular phones, substitutive hormonal therapy, pesticides, and diet have been published. To date, results have been discordant. Descriptive epidemiological studies have reported an increasing annual incidence of primary brain tumors in industrialized countries. The main reasons are the increasing age of the population and better access to diagnostic imaging. Comparing incidences from one registry to another is difficult. Spatial and temporal variations constitute one explanation and evolutions in coding methods another. In all registries, weak incidence of primary brain tumors constitute a very important limiting factor. Renewed interest from the neuro-oncological community is needed to obtain pertinent and essential data which could facilitate improved knowledge on this topic.

Environmental risk factors for brain tumors

Primary brain tumors, whether malignant or nonmalignant, have devastating consequences. Unfortunately, few known causes exist. Despite decades of epidemiologic research to identify environmental causes of brain tumors, very little progress has been made. The purpose of this paper is to review the most recent studies in the epidemiology of brain tumors. Popular topics of interest in adult brain tumor epidemiology include electromagnetic fields (particularly cellular phones), occupational exposures, nitroso-containing compounds (especially smoking), hair products, and allergic and immunologic factors. Some of these topics are also applicable to the etiology of childhood brain tumors, but additional areas of interest in the pediatric population focus on parental exposure prior to conception, maternal exposure during pregnancy, and childhood exposure to infectious agents. After an extensive review of the literature since 2001, we present the most relevant studies. Although there are many proposed associations with brain tumors, none possess the statistical significance to confidently ascribe causation. However, new findings and associations, particularly those in allergy and immunology, will present interesting opportunities for further development.

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.

Hair dyes and risk of glioma among Nebraska women

The etiology of brain cancer is not well understood. We conducted a population-based case-control study among 112 white women in Nebraska who were newly diagnosed with glioma between July 1988 and June 1993, and 215 controls, to identify risk factors for this disease. A 1.7-fold increased risk of glioma was observed for women who ever used hair coloring products (95% confidence interval (CI) = 1.0-2.9, 62 cases), and a 2.4-fold risk for those who used permanent hair coloring products (odds ratio (OR) = 2.4, 95% CI = 1.3-4.5, 39 cases). For women with the most aggressive form of glioma, glioblastoma multiforme, risk increased with duration of exposure to 4.9 (95% CI = 1.6-15.7, 10 cases) after 21 or more years of permanent hair coloring use. Higher risks were observed with earlier age at first use, but we did not see an exposure-response pattern with frequency of use of permanent dyes. No association was observed with use of non-permanent (sometimes called temporary or semi-permanent) hair coloring products. These suggestive findings need confirmation in future studies with larger sample sizes, fewer proxy respondents, and the ability to evaluate the effect of changes in formulations over time.

Environmental exposure to residential pesticides, chemicals, dusts, fumes, and metals, and risk of childhood germ cell tumors

We examined relationships between exposure to residential pesticides, chemicals, dusts, fumes, and metals, and childhood germ cell tumors (GCTs) in the largest case-control study to date on the topic. We recruited 272 children under 15 years old who had GCT diagnosed between January 1, 1993 and December 31, 2001. Controls were selected by random-digit dialing and were frequency matched to cases by sex, age, and geographic area. Telephone interviews and self-administered questionnaires of parents were used to collect exposure information. We used unconditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI). Maternal and paternal exposure from 6 months before pregnancy to during breastfeeding and children's postnatal exposure to residential pesticides were generally unrelated to risk of childhood GCT. Elevated OR were observed for mothers' exposure to hair dyes 1 month before pregnancy for boys (OR = 1.7, 95% CI = 1.0-2.8) and during breastfeeding for boys and girls combined, and for girls (OR = 1.5, 95% CI = 1.0-2.2 and OR = 1.7, 95% CI = 1.1-2.6, respectively). Among boys, OR for paternal exposure to insecticides more often than four times or exposure to indoor insecticides more often than three times were 0.5 (95% CI = 0.2-0.9, trend test p = 0.05) and 0.3 (95% CI = 0.2-0.8, trend test p = 0.02) during the index pregnancy. Overall this study produced no strong evidence linking parental and child residential exposure to pesticides, certain chemicals, dusts, fumes, and metals to increased risk of childhood GCT. Statistically significant associations need to be confirmed in future studies.

Beauty product-related exposures and childhood brain tumors in seven countries: results from the SEARCH International Brain Tumor Study

Data from 1218 cases of childhood brain tumors (CBT) diagnosed between 1976 and 1994 and 2223 matched controls from the general population were included in an analysis of maternal beauty product exposure and beauty-related employment in 9 centers in 7 countries. A 50% increased odds ratio (OR) [95% confidence interval (CI) = 1.0-2.1] for CBT was observed among children of mothers who were exposed via personal use of and/or possible ambient contact with beauty products during the 5 years preceding the index child's birth compared with children of mothers never exposed to beauty products during this time period. Overall maternal personal use of hair-coloring agents in the month before or during the pregnancy of the index child's birth was not associated with CBT (OR = 1.0, CI = 0.83-1.3) or with astroglial (OR = 1.1, CI = 0.85-1.4), PNET (OR = 1.0, CI = 0.71-1.5) and other glial subtypes (OR = 1.0, CI = 0.62-1.0). Similarly, no statistically increased ORs or discernable pattern of risk estimates were observed for period of use or for number of applications per year for maternal personal use of hair-coloring agents overall or by histologic type. Among children born on or after 1980, increased ORs for CBT were associated with maternal non-work-related exposure to any beauty products (OR = 2.6, CI = 1.2-5.9), hair-dyes (OR = 11, CI = 1.2-90), and hair sprays (OR = 3.4, CI = 1.0-11). No overall increased OR for CBT was observed among children of mothers employed in beauty-related jobs during the 5 years preceding the index child's birth compared with those who reported no beauty-related employment. In general, other specific beauty product-related exposures were not associated with increased ORs for CBT. Data from our study provide little evidence of an increased risk for CBT with mothers' exposures to beauty products.

Maternal hair dye use and risk of neuroblastoma in offspring*

OBJECTIVE

Studies have suggested an association between maternal hair dye use and elevated risk of childhood cancer, including neuroblastoma. We analyzed data from a large case-control study to investigate the relationship between maternal hair dye use around pregnancy and risk of neuroblastoma in offspring.

METHODS

Cases were children with neuroblastoma diagnosed between 1992 and 1994 at hospitals in the United States and Canada participating in the Children's Cancer Group or the Pediatric Oncology Group. Random-digit dialing was used to identify one matched control for each case. Information on hair dye use was gathered from telephone interviews of 538 case and 504 control mothers.

RESULTS

Use of any hair dye in the month before and/or during pregnancy was associated with a moderately increased risk of neuroblastoma (adjusted odds ratio (OR) = 1.6; 95% confidence interval (CI) = 1.2-2.2). Temporary hair dye use (OR = 2.0, CI = 1.1-3.7) was more strongly associated with neuroblastoma than use of permanent hair dye (OR = 1.4, CI = 1.0-2.0).

CONCLUSION

Although the results of this study provide evidence of an association between maternal hair dye use and neuroblastoma, further research is necessary to evaluate effects by method of hair dye application, color, and chemical composition.

Photodegradation of azodyes: comparison of different catalytic systems and control of the effective mineralisation

Three different azodyes were used as target molecules to test the efficiency of the photodegradation process catalysed by titanium dioxide under UV irradiation. A comparison of different catalytic systems was performed using the catalyst both free in solution (system I) and immobilised in a polymeric membrane (system II). Iron oxalate and a conducting polymer (polyaniline, PA) were added to the I and II systems respectively to check an eventual synergetic effect. The research evolved through three different steps involving each one the use of a different analytical method. Shortly, the UV spectrophotometry were preliminarily used to monitor the bleaching process and allowed to choose the best catalytic system, HPLC and GC/MS were used to monitor the appearance and disappearance of the photodegradation intermediates and, lastly, the effective mineralisation was tested by an indirect ICP (Inductively Coupled Plasma) determination of the produced carbon dioxide.