Overcoming False-Negative Patch Tests: A Systematic Literature Review

Exogenous allergens, found in cosmetic products, jewelry items, antiseptics and antibacterials, plants, and solvents, can cause clinical allergic contact Dermatitis (ACD). To help identify and discern which allergen is causing ACD, clinicians use patch tests, but they can yield false-negative results at times. Examining potential reasoning for false negatives is particularly helpful when a patient's history and physical examination strongly suggest ACD, and the patch test is negative. A strong history and physical presentation suggestive of ACD warrants additional patch testing or other methods to verify a false-negative patch test result. We conducted a literature review to compile various reasonings and solutions for false-negative patch tests in suspected ACD patients. Utilizing EMBASE, Scopus, PubMed, and Google Scholars, 49 articles were included by using search terms such as "False negative patch test" or "False-negative patch test" and "allergic contact Dermatitis," or "ACD." Common factors that led to false-negative patch test results include low allergen concentration, inadequate percutaneous penetration, technique error, immunosuppressive therapy, and ultraviolet exposure. Potential solutions include using different vehicles, concentration, increasing reading time, repeating the patch test, intradermal testing, and repeat open application testing. If a false-negative patch test is suspected, then intradermal testing can be administered to ensure the specificity of the patch test result. Considering the main contributing factors and solutions to false-negative patch tests, clinicians can accurately diagnose ACD and administer proper treatment plans.

Association of p-phenylenediamine exposure with alterations of pulmonary function, pruritus and health-related quality of life in hair dye factory workers: a cross-sectional study

P-Phenylenediamine (PPD) is a common component of hair dye, which can cause skin contact allergy and asthma with impaired pulmonary function. However, the adverse effects of occupational exposure to different dose PPD was rarely mentioned. We recruited 124 workers from a hair dye factory to explore the association of occupational PPD exposure on pulmonary function, pruritus and health related quality of life (HRQL). We categorized exposure to PPD into 3 levels: lower exposure group (< 0.00001 mg/m³); middle exposure group (0.00001-0.00033 mg/m³); higher exposure group (0.00033-0.047 mg/m³). The HRQL and subjective pruritus of the workers were assessed by the short form 36 health survey (SF-36) and Visual analogue scale (VAS) of pruritus, respectively. In the high PPD-exposed group, the percentage of FEV1 (FEV1%) was lower in higher exposure group compared with lower exposure group. The FEV1/FVC was also lower in comparison to the higher exposure and middle exposure groups (p < 0.05). PPD levels were negatively correlated with vitality and mental health (p < 0.01). The structural equation model showed the positive effects of PPD on VAS level (β = 0.213, p < 0.001), and indicated partly negtive effects of PPD on total score of SF-36 (β = - 0.465, p = 0.002), respectively. Our results indicate that occupational exposure to PPD might be associated with pulmonary function impairment, poor HRQL, and subjective pruritus of the workers.

Para-phenylenediamine deteriorates oocyte quality by impairing mitochondrial function

Several studies demonstrate that para-phenylenediamine (PPD) is often added to permanent oxidative hair dyes. Sub-chronic topical exposure to PPD in male rats damages their testicular function; however, little is known about the effects of PPD exposure on the female reproductive system, especially on oocyte quality. In this study, we found that PPD can affect the meiotic capacity of oocytes and their fertilization potential. In particular, PPD can damage the spindle/chromosome structure and prevent oocytes from developing and maturing normally. Furthermore, PPD exposure compromised the dynamics of cortical granules and their component, ovastacin. In addition to the protein level of Juno, the sperm receptors on the egg membrane, were substantially impaired in PPD-administered oocytes, thus leading to fertilization failure. Finally, we found that PPD exposure resulted in abnormal mitochondrial function, which led to oocyte degeneration, apoptosis, and increased ROS levels. Altogether, our study illustrates that mitochondrial dysfunction and redox perturbation are the major causes of the poor quality of oocytes exposed to PPD.

Investigations on detoxification mechanisms of novel para-phenylenediamine analogues through N-acetyltransferase 1 (NAT-1)

Para-phenylenediamine (PPD) is one of the most used chemicals in oxidative hair dyes. However, its use has been associated with adverse effects on health, including contact dermatitis and other systemic toxicities. Novel PPD derivatives have been proposed as a safer replacement for PPD. This can be achieved if these molecules minimally permeate the skin and/or are easily metabolised by enzymes in the skin (e.g., N-acetyltransferase-1 (NAT-1)) into innocuous compounds before gaining systemic entry. This study investigated the detoxification pathway mediated by NAT-1 enzymes on 6 synthesized PPD analogues (namely, P1-P6) with different chemical properties, to study the role of functional groups on detoxification mechanisms in HaCaT skin cells. These compounds were carefully designed with different chemical properties (whereby the ortho position of PPD was substituted by nucleophile and electrophile groups to promote N-acetylation reactions, metabolism and clearance). Compounds P2-P4 N-acetylated at 54-49 nmol/mg/min, which is 1.6 times higher than N-acetylation of PPD, upregulated NAT-1 activity from 8-7% at 50 μM to 22-11% at 100 μM and showed 4 times higher rate of elimination (k equal to 0.141 ± 0.016-0.124 ± 0.01 h^-1) and 3 times faster rate of clearance (0.172 ± 0.007-0.158 ± 0.005 h^-1mgprotein^-1) than PPD (0.0316 ± 0.0019 h^-1, 0.0576 ± 0.003 h^-1mg protein^-1, respectively). The data suggest that nucleophile substituted compounds detoxify at a faster rate than PPD. Our metabolic and detoxification mechanistic studies revealed significantly higher rates of N-acetylation, NAT-1 activity and higher detoxification of P2-P4 in keratinocytes, suggesting the importance of nucleophilic groups at the ortho position in PPD to reduce toxicity of aniline-based dyes on human skin cells.

Contact Dermatitis Associated With Hair Care Products: A Retrospective Analysis of the North American Contact Dermatitis Group Data, 2001-2016

BACKGROUND

Hair care products (HCPs) may cause both allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD).

OBJECTIVES

The aims of the study were to determine the prevalence of HCP-associated ICD/ACD and to characterize relevant allergens.

METHODS

This study is a retrospective analysis of North American Contact Dermatitis Group (NACDG) patch test data, 2001-2016.

RESULTS

Of 38,775 patients tested, 3481 (9.0%) had positive patch test reactions associated with HCPs. The HCP-positive patients were significantly more likely to be female (79.9% vs 66.0%) and/or have primary sites of dermatitis on the face (32.0% vs 27.8%) or scalp (15.4% vs 2.2%) compared with the HCP-negative patients (P < 0.0001). Of 4908 HCP-associated positive patch test reactions, 86.9% (n = 4263) were due to allergens on the NACDG screening series; p-phenylenediamine (35.8%), methylisothiazolinone (9.7%), methylchloroisothiazolinone/methylisothiazolinone (8.7%), and cocamidopropyl betaine (5.9%) were the most frequent. Most reactions (87.7%, 3736/4263) were currently clinically relevant. The most common job associated with 366 occupationally related NACDG HCP-associated allergens was hairdresser/cosmetologist (71.9%). Two hundred eighty-two patients (0.7%) had ICD associated with HCPs. Shampoo/conditioners were the most frequent source of NACDG HCP-associated reactions (47.3%) and HCP-associated ICD (45.0%).

CONCLUSIONS

Of the HCP-positive patients, 18.5% had HCP reactions to allergens not on the NACDG screening series, underscoring the importance of patch testing to expanded series in patients suspected of HCP allergy.

Development of novel alternative hair dyes to hazardous para-phenylenediamine

Most of the permanent hair dye products contain p-phenylenediamine (PPD), a well-known skin sensitizer. PPD may cause cutaneous reactions and leads to allergic contact dermatitis (ACD), a condition with major medical and financial repercussions. Hair dye-induced ACD represents a growing concern both for consumers and the cosmetics industry. In this study we introduced novel side chains on the PPD molecule with the goal of overcoming the hazard potential of PPD. Our strategy relies on the replacement of the colorless PPD with new, larger and intrinsically colorled PPD derivatives to reduce dermal penetration and thus the skin sensitization potential. We synthesized two oligomers with bulky side-chains, which displayed 7-8 times lower cytotoxicity than PPD, a significantly weaker sensitization potential (22.0 % and 23.8 % versus 55.5 % for PPD) in the Direct Peptide Reactivity Assay, minimal cumulative penetration through excised skin and an intrinsic ability to colour and preserve the nuance when applied on bleached hair. The lower skin permeation and sensitizing potential are absolutely crucial and give a clear advantage of our products over other standards. These novel PPD hair dyes show significantly less hazard potential than PPD and may, upon further risk assessment studies, replace PPD in consumer care products.

Hair dye and risk of skin sensitization induction: a product survey and quantitative risk assessment for para-phenylenediamine (PPD)

BACKGROUND

Para-Phenylenediamine (PPD) is a commonly used dye intermediate in permanent hair dye formulations, and exposure to PPD has been associated with allergic contact dermatitis at certain doses.

PURPOSE

Determine the concentration of PPD in a survey of self-application permanent hair dye products, and perform a quantitative risk assessment to determine the risk of skin sensitization induction following application of these products.

METHODS

Consumer exposure levels (CELs) to PPD following application of hair dye products were estimated using the maximum amount of hair dye that can adhere to the surface area of the scalp, the measured concentration of PPD in the hair dye product, a retention factor, the dermal absorption of PPD, and the surface area of the scalp. CELs were calculated for various exposure scenarios, and were stratified by hair dye shade.

RESULTS

All estimated CELs did not exceed the acceptable exposure level. Specifically, margins of safety ranged from 2.3 to 1534 for black dyes, 2.9 to 5031 for brown dyes, and 26 to 5031 for blonde dyes.

CONCLUSIONS

Findings suggest that use of the evaluated permanent hair dyes, under the evaluated exposure scenarios, would not be expected to induce skin sensitization due to PPD exposure at concentrations ≤0.67%.

Determination of phenylenediamines in hair colors derivatizated with 5-(4, 6-dichlorotriazinyl)aminofluorescein via micellar electrokinetic chromatography

Phenylenediamines (PDs), which are reported to cause allergic dermatitis and possess genotoxicity and carcinogenicity, are the ingredients used in permanent hair dyes. The fluorescent derivatization strategy coupled with micellar electrokinetic chromatography (MEKC) were established to analyze four PDs, including o-phenylenediamine (OPD), m-phenylenediamine (MPD), p-phenylenediamine (PPD) and toluene-2,5-diamine (PTD). Additionally, 5-(4, 6-dichlorotriazinyl) aminofluorescein (DTAF) was used as a fluorescent reagent derived at amino groups of PDs and underwent nucleophilic substitution reaction to improve the detection sensitivity. The derivatization condition reacted at 90 °C for 10 min in alkaline conditions. The optimized separation conditions were 20 mM borate (pH 8.0) containing 10 mM Brij 35 and 35% (v/v) methanol. The limits of detection (S/N = 3) for MPD, PTD, PPD and OPD were 25, 25, 50 and 100 nM, respectively. Compared to MEKC-UV, the sensitivity enhancements were 30- to 81-fold when PDs were derived with DTAF. The high-sensitivity MEKC-LIF method was successfully established and applied to determine PDs in commercial hair colors for quality control and in real hair samples for evaluating the location of PDs in dyed hair samples, as well as in percutaneous absorption samples for evaluating the ability of PDs to penetrate skin.

P-Phenylenediamine Hair Dye Allergy and Its Clinical Characteristics

Background

P-phenylenediamine (PPD) has been identified as the most frequent contact sensitizer of hair dye and the clinical characteristics of hair dye contact allergy (HDCA) are diverse.

Objective

The purpose of this study was to identify the clinical characteristics of HDCA and to assess the relationships between HDCA, exposure time to PPD and PPD positivity.

Methods

We analyzed 105 patients with patch test-confirmed hair dye allergy who presented between July 2009 and March 2015. Clinical symptoms, signs, associated skin diseases, involved ACD area, and patterns of hair dye use were obtained by reviewing medical records and by interview.

Results

HDCA was more common in women and in individuals aged more than 50 years. Pruritus was the most common symptom; erythematous macules and patches were the most frequently observed clinical signs. The most common site of HDCA was the face and non-specific eczema and urticaria were frequently observed with HDCA. Exposure time to hair dye, represented as frequency and duration, showed a positive correlation with the area affected by hair dye allergy (p<0.001). Hair dye allergy was identified in most patients (80%) before diagnosis by patch test. However, only 28.6% of all patients stopped using hair dye, even after the diagnosis was confirmed.

Conclusion

The extent of hair dye allergy involvement was related to exposure time to hair dye. For effective treatment of HDCA, it is important to properly educate patients with HDCA about the clinical manifestations of HDCA and to keep away from allergens.

Two decades of p-phenylenediamine and toluene-2,5-diamine patch testing - focus on co-sensitizations in the European baseline series and cross-reactions with chemically related substances

BACKGROUND

Cross-reactions and co-sensitizations are of great importance in understanding contact allergy and exposure sources.

OBJECTIVES

To investigate common cross-reactions and co-sensitizations in p-phenylenediamine (PPD)-sensitized and toluene-2,5-diamine (TDA)-sensitized individuals.

METHODS

From our patch test population, 8036 patients patch tested with the European baseline series were extracted. Readings had to be performed at least on day 3 according to ICDRG guidelines.

RESULTS

Two hundred and fifty-one patients were sensitized to PPD and/or TDA; 231 patients were sensitized to PPD, and 109 to TDA. Significant differences were observed regarding the strengths of patch test reactions to PPD and number of cross-reactions. For TDA, a difference was found between all reaction strengths, except between + and ++ strengths. PPD-sensitized individuals were more likely to be sensitized to carba mix, cobalt chloride, colophonium, p-tert-butyl phenolformaldehyde resin, paraben mix, and methylisothiazolinone. TDA-sensitized individuals were more often sensitized to carba mix.

CONCLUSIONS

Cross-reactivity was commonly found among individuals sensitized to PPD or TDA, and was strongly related to the strength of the patch test reaction. Regarding co-sensitizations, a frequently appearing or common exposure source could not be determined. However, modification of the allergen by, for example, the skin microbiota may have caused the formation of molecules that are, for the human immune system, indistinguishable from PPD.

Prevalence of Contact Allergy to p-Phenylenediamine in the European General Population

Population-based studies on contact allergy to p-phenylenediamine (PPD) are scarce. A cross-sectional study was performed to assess the prevalence of contact allergy to PPD and its risk factors in the general population of 5 European countries. A total of 10,425 subjects were interviewed, and a random sample (n = 2,739) was patch tested to PPD. Overall, 5,286 individuals (50.9%) reported having used hair colorants at least once in their lifetime (78% female, 20% male), and 35% had used hair colorants during the last 12 months. Hair colorant avoidance because of any skin problem during the lifetime was reported by 6%. Black henna tattoos had been used by 5.5% during their lifetime. The prevalence of PPD contact allergy was 0.8% (95% confidence interval 0.6-1.0%), with no statistically significant association with gender or hair dye use. The prevalence of PPD in black henna tattoo users was 3.2% versus 0.6% in nonusers (P < 0.001). A clinically relevant positive patch test reaction to PPD related to hair coloring products was found in 0.1% (95% confidence interval 0.0-0.2%). A significant association with PPD contact allergy was observed for subjects who had black henna tattoos in their lifetime, with an age- and gender-adjusted odds ratio of 9.33 (95% confidence interval 3.45-25.26, P < 0.001). Black henna tattoos are an important risk factor for PPD contact allergy.

Influence of vitamin C on the elicitation of allergic contact dermatitis to p-phenylenediamine

BACKGROUND

Hair dyes represent one of the most important causes of allergic contact dermatitis resulting from the use of cosmetic products. The principal causative chemistry is associated with oxidation products of p-phenylenediamine (PPD) and closely related substances.

OBJECTIVES

To examine whether prior application of the antioxidant vitamin C to the skin was able to reduce the cutaneous allergic response to PPD.

METHODS

Twenty eight volunteers with a proven history of contact allergy to PPD were recruited. Each was tested with a range of PPD doses and PPD-containing hair dye on untreated skin and skin pretreated for 10 min with a vitamin C formulation.

RESULTS

Pretreatment of skin sites with vitamin C led to a reduction in the intensity, or even ablation, of the cutaneous allergic reaction to PPD in ∼75% of cases as compared with untreated skin.

CONCLUSIONS

The results suggest that treatment of the skin adjacent to the hair-bearing area with antioxidant could form part of a strategy to reduce the burden of cosmetic allergic contact dermatitis caused by hair dyeing.

p-Phenylenediamine and other allergens in hair dye products in the United States: a consumer exposure study

BACKGROUND

Hair dye products constitute an important source of allergen exposure, and contribute importantly to allergic contact dermatitis in consumers and hairdressers.

OBJECTIVES

To evaluate the presence of potent contact sensitizers in oxidative hair dye products intended for home use on the US market.

METHODS

Ingredient labels of 107 hair dyes from 10 major brands were examined and used to assess the prevalence of hair dye substances known to be potent contact sensitizers.

RESULTS

One hundred and six of 107 (99%) products contained at least one potent sensitizer, and the average product contained six (range 0-11). p-Phenylenediamine (PPD) was found in 83 products (78%), but resorcinol (89%), m-aminophenol (75%), p-aminophenol (60%) and toluene-2,5-diamine (21%) were also frequently identified.

CONCLUSIONS

Potent contact sensitizers were almost universally included in the hair dyes investigated in the United States. Although PPD is a common allergen, resorcinol and m-aminophenol were found more frequently. In total, 30 potent sensitizers were found. Clinicians should consider other allergens in addition to PPD when evaluating patients with suspected hair dye allergy.

Systemic immunogenicity of para-Phenylenediamine and Diphenylcyclopropenone: two potent contact allergy-inducing haptens

p-Phenylenediamine (PPD) and Diphenylcyclopropenone (DPCP) are two potent haptens. Both haptens are known to cause delayed-type hypersensitivity, involving a cytokine response and local infiltration of T-cell subpopulations, resulting in contact dermatitis. We investigated the systemic immune effects of PPD and DPCP, two relatively unexplored skin allergens. The dorsal sides of the ears of BALB/c mice were exposed to PPD or DPCP (0.1% w/v or 0.01% w/v), or vehicle alone. Mice were treated once daily for 3 days (induction period) and subsequently twice per week for 8 weeks. Local and systemic immune responses in the auricular and pancreatic lymph nodes, spleen, liver, serum, and ears were analyzed with cytokine profiling MSD, flow cytometry, and qPCR. Ear swelling increased significantly in mice treated with 1% PPD, 0.01% DPCP or 0.1% DPCP, compared with vehicle treatment, indicating that the mice were sensitized and that there was a local inflammation. Auricular lymph nodes, pancreatic lymph nodes, spleen, and liver showed changes in regulatory T-cell, B-cell, and NKT-cell frequencies, and increased activation of CD8(+) T cells and B cells. Intracellular cytokine profiling revealed an increase in the IFN-γ- and IL-4-positive NKT cells present in the liver following treatment with both haptens. Moreover, we saw a tendency toward a systemic increase in IL-17A. We observed systemic immunological effects of PPD and DPCP. Furthermore, concentrations too low to increase ear thickness and cause clinical symptoms may still prime the immune system. These systemic immunological effects may potentially predispose individuals to certain diseases.

An efficient and rapid thin-layer chromatography method for the identification of 32 dye substances in hair dye products

OBJECTIVE

The use of dye substances in hair dye products has led to controversial public and scientific discussions about their impact on human health. This study aimed to explore a rapid method for identification of dye substances in hair dye products.

METHODS

Thin layer chromatography (TLC) method was conducted in this study. We developed basic data of 32 dye substances by 4 developing solvents and 2 indicator sprays. The dye substances were identified by comparing the Rf values and colors between samples and reference substances.

RESULTS

Thirty samples were identified by the established method. 22 hair dye substances were detected in 16 formula known samples, 15 hair dye substances were detected in 14 formula unknown samples. Four laboratories participated in the validation and the results showed good interlaboratory reproducibility.

CONCLUSION

The developed TLC method is simple, rapid, reliable and can be finely used for identification of dye substances in hair dye products.

Introduction of a methoxymethyl side chain into p-phenylenediamine attenuates its sensitizing potency and reduces the risk of allergy induction

The strong sensitizing potencies of the most important primary intermediates of oxidative hair dyes, p-phenylenediamine (PPD) and p-toluylenediamine (PTD, i.e. 2-methyl-PPD) are well established. They are considered as the key sensitizers in hair dye allergic contact dermatitis. While modification of their molecular structure is expected to alter their sensitizing properties, it may also impair their color performance. With introduction of a methoxymethyl side chain we found the primary intermediate 2-methoxymethyl-p-phenylenediamine (ME-PPD) with excellent hair coloring performance but significantly reduced sensitizing properties compared to PPD and PTD: In vitro, ME-PPD showed an attenuated innate immune response when analyzed for its protein reactivity and dendritic cell activation potential. In vivo, the effective concentration of ME-PPD necessary to induce an immune response 3-fold above vehicle control (EC3 value) in the local lymph node assay (LLNA) was 4.3%, indicating a moderate skin sensitizing potency compared to values of 0.1 and 0.17% for PPD and PTD, respectively. Finally, assessing the skin sensitizing potency of ME-PPD under consumer hair dye usage conditions through a quantitative risk assessment (QRA) indicated an allergy induction risk negligible compared to PPD or PTD.

Penetration and haptenation of p-phenylenediamine

Although p-phenylenediamine (PPD) has been recognized as an extreme sensitizer for many years, the exact mechanism of sensitization has not been elucidated yet. Penetration and the ability to bind to proteins are the first two hurdles that an allergen has to overcome to be able to sensitize. This review is an overview of studies regarding PPD penetration through skin (analogues) and studies on the amino acids that are targeted by PPD. To complete this review, the auto-oxidation and N-acetylation steps involved in PPD metabolism are described. In summary, under normal hair dyeing exposure conditions, <1% of the applied PPD dose penetrates the skin. The majority (>80%) of PPD that penetrates will be converted into the detoxification products monoacetyl-PPD and diacetyl-PPD by the N-acetyltransferase enzymes. The small amount of PPD that does not become N-acetylated is susceptible to auto-oxidation reactions, yielding protein-reactive PPD derivatives. These derivatives may bind to specific amino acids, and some of the formed adducts might be the complexes responsible for sensitization. However, true in vivo evidence is lacking, and further research to unravel the definite mechanism of sensitization is needed.

A survey of the awareness, knowledge and behavior of hair dye use in a korean population with gray hair

Background

Gray hair naturally develops in the process of human aging. Many people with gray hair periodically dye their hair. Hair dyeing products are widely used and they can cause adverse effects. Therefore, the user's knowledge and recognition about hair dyeing and related side effects are important.

Objective

The goal of this study was to lay the foundation for understanding, preventing and treating side effects caused by hair coloring products.

Methods

We conducted a questionnaire survey for adult males and females aged over 20 who had gray hair. A total of 500 subjects were included in this study and statistical analysis was performed.

Results

Large numbers of the people who had experience with hair dye (233 out of 319 people, 73.0%) did not know about the exact brand name of the hair dye product that they were using. Of 319 hair dye users, 23.8% (76 out of 319) people stated that they experienced side effects. Despite the occurrence of side effects from hair dyeing products, it seems they did not realize the seriousness of the side effects or the need for treatment.

Conclusion

It is advisable to introduce a system that enables users to become aware of the ingredients and side effects of hair coloring products and give opportunities for users to become aware of the side effects of hair coloring through education, publicity and publication of an informational booklet.

p-Phenylenediamine and other hair dye sensitizers in Spain

BACKGROUND

Oxidative hair dyes are important skin sensitizers, causing contact allergy and dermatitis in hairdressers and consumers.

OBJECTIVES

To study the prevalence of hair dye substances, categorized as potent skin sensitizers, in consumer-available oxidative hair dye products on the market of a southern European country and to compare it with that in Sweden.

METHODS

Ingredient labels of 105 oxidative hair dye products from 19 brands were studied, and the prevalence and use pattern of hair dye substances, categorized as potent skin sensitizers, was assessed. Network diagrams were used to display results.

RESULTS

According to the labelling, all 105 products contained hair dye substances categorized as potent skin sensitizers. A total of 25 different hair dye substances categorized as potent skin sensitizers were identified. Eighty-seven per cent of the products contained at least four such substances. Either p-phenylenediamine, toluene-2,5-diamine or toluene-2,5-diamine sulfate was present in 103 products.

CONCLUSIONS

Hair dye substances categorized as potent skin sensitizers were used in all studied hair dye products on the Spanish market. The prevalence of p-phenylenediamine was higher in the present study than in a similar study in Sweden. More than 20 potent sensitizers were identified in each country. Not only p-phenylenediamine should be used to diagnose allergy to hair dyes.

Knowledge and practices of, and attitudes towards, the use of hair dyes among females visiting a teaching hospital in Riyadh, Saudi Arabia

BACKGROUND AND OBJECTIVES

Use of hair dye is extremely common worldwide. However, our literature search failed to find studies concerning the knowledge and attitudes of the public with regard to hair dyes. We sought to explore the knowledge and practices of, and attitudes towards, the use of hair dye among females.

DESIGN AND SETTING

A cross-sectional survey conducted on females who attended various outpatient clinics at King Khalid University Hospital in Riyadh, Saudi Arabia, a tertiary referral hospital open to the general public.

PATIENTS AND METHODS

A self-administered questionnaire about the use of hair dyes was distributed randomly among females attending the outpatient clinics at a university hospital in 2008.

RESULTS

The response rate was 87.2%, with completion of 567 of the 650 distributed questionnaires. The mean (SD) age of respondents was 32.0 (10.2) years. Among respondents, 82.6% (464/562) had at some point dyed their hair. Furthermore, 69.3% (334/482) had dyed their hair in the past 12 months. The mean (SD) age of the participants when they first dyed their hair was 22.2 (7.1) years (range, 7-50). Of the participants, 76.8% (354/461) used permanent dyes, and about the same percentage of participants believed such dyes were the safest hair dye type. However, 52.4% (278/531) of the participants believed that hair dyes are harmful, and 36% (191/531) believed that hair dyes could cause cancer. Younger females tend to dye their hair less frequently (P<.001), whereas those with less education tend to dye their hair more frequently (P=.013).

CONCLUSION

Use of hair dye is very common among females. Because the practice starts at a very young age, we conclude that hair dyes are overused and misused. The public should be informed about the risks associated with excessive hair dye use.

Safety assessment of personal care products/cosmetics and their ingredients

We attempt to review the safety assessment of personal care products (PCP) and ingredients that are representative and pose complex safety issues. PCP are generally applied to human skin and mainly produce local exposure, although skin penetration or use in the oral cavity, on the face, lips, eyes and mucosa may also produce human systemic exposure. In the EU, US and Japan, the safety of PCP is regulated under cosmetic and/or drug regulations. Oxidative hair dyes contain arylamines, the most chemically reactive ingredients of PCP. Although arylamines have an allergic potential, taking into account the high number of consumers exposed, the incidence and prevalence of hair dye allergy appears to be low and stable. A recent (2001) epidemiology study suggested an association of oxidative hair dye use and increased bladder cancer risk in consumers, although this was not confirmed by subsequent or previous epidemiologic investigations. The results of genetic toxicity, carcinogenicity and reproductive toxicity studies suggest that modern hair dyes and their ingredients pose no genotoxic, carcinogenic or reproductive risk. Recent reports suggest that arylamines contained in oxidative hair dyes are N-acetylated in human or mammalian skin resulting in systemic exposure to traces of detoxified, i.e. non-genotoxic, metabolites, whereas human hepatocytes were unable to transform hair dye arylamines to potentially carcinogenic metabolites. An expert panel of the International Agency on Research of Cancer (IARC) concluded that there is no evidence for a causal association of hair dye exposure with an elevated cancer risk in consumers. Ultraviolet filters have important benefits by protecting the consumer against adverse effects of UV radiation; these substances undergo a stringent safety evaluation under current international regulations prior to their marketing. Concerns were also raised about the safety of solid nanoparticles in PCP, mainly TiO(2) and ZnO in sunscreens. However, current evidence suggests that these particles are non-toxic, do not penetrate into or through normal or compromised human skin and, therefore, pose no risk to human health. The increasing use of natural plant ingredients in personal care products raised new safety issues that require novel approaches to their safety evaluation similar to those of plant-derived food ingredients. For example, the Threshold of Toxicological Concern (TTC) is a promising tool to assess the safety of substances present at trace levels as well as minor ingredients of plant-derived substances. The potential human systemic exposure to PCP ingredients is increasingly estimated on the basis of in vitro skin penetration data. However, new evidence suggests that the in vitro test may overestimate human systemic exposure to PCP ingredients due to the absence of metabolism in cadaver skin or misclassification of skin residues that, in vivo, remain in the stratum corneum or hair follicle openings, i.e. outside the living skin. Overall, today's safety assessment of PCP and their ingredients is not only based on science, but also on their respective regulatory status as well as other issues, such as the ethics of animal testing. Nevertheless, the record shows that today's PCP are safe and offer multiple benefits to quality of life and health of the consumer. In the interest of all stakeholders, consumers, regulatory bodies and producers, there is an urgent need for an international harmonization on the status and safety requirements of these products and their ingredients.