Quantitative risk assessment for the induction of allergic contact dermatitis: uncertainty factors for mucosal exposures

Weight of Evidence Approach for Skin Sensitization Potency Categorization of Fragrance Ingredients

Reliable human potency data are necessary for conducting quantitative risk assessments, as well as development and validation of new nonanimal methods for skin sensitization assessments. Previously, human skin sensitization potency of fragrance materials was derived primarily from human data or the local lymph node assay.

Updating exposure assessment for skin sensitization quantitative risk assessment for fragrance materials

In 2008, a proposal for assessing the risk of induction of skin sensitization to fragrance materials Quantitative Risk Assessment 1 (QRA1) was published. This was implemented for setting maximum limits for fragrance materials in consumer products. However, there was no formal validation or empirical verification after implementation. Additionally, concerns remained that QRA1 did not incorporate aggregate exposure from multiple product use and included assumptions, e.g. safety assessment factors (SAFs), that had not been critically reviewed. Accordingly, a review was undertaken, including detailed re-evaluation of each SAF together with development of an approach for estimating aggregate exposure of the skin to a potential fragrance allergen. This revision of QRA1, termed QRA2, provides an improved method for establishing safe levels for sensitizing fragrance materials in multiple products to limit the risk of induction of contact allergy. The use of alternative non-animal methods is not within the scope of this paper. Ultimately, only longitudinal clinical studies can verify the utility of QRA2 as a tool for the prevention of contact allergy to fragrance materials.

Differential susceptibility between skin and vaginal mucosa in sensitization phase of allergic contact dermatitis in mice

Introduction

Mechanisms underlying skin sensitization in allergic contact dermatitis have been actively studied using the murine contact hypersensitivity (CHS) model. However, much less is known about sensitization at the vaginal mucosa (VM).

Methods

We developed a CHS model with VM sensitization and epicutaneous elicitation at the ear. We then examined the proliferation activity of lymphocytes, the frequencies of T cells and the differentiation of hapten‐specific T cells in draining lymph nodes (dLNs) after sensitization.

Results

Hapten‐specific CHS responses to 2,4‐dinitrofluorobenzene (DNFB), 2,4,6‐trinitrochrolobenzene, and oxazolone assessed by ear swelling suggested that the VM would be an inductive site of CHS to haptens. In the comparisons of CHS responses to each of the three haptens examined, the lower responses in VM‐sensitized mice were observed than skin‐sensitized mice (e.g., DNFB‐induced responses, −56%; p < .001, at 48 h after challenge). Consistent with the CHS responses, the DNFB‐induced proliferation of cells in dLNs examined by 5‐bromo‐2ʹ‐deoxyuridine assay was lower (−62%; p < .001) in VM‐sensitized mice than skin‐sensitized mice. On the other hand, between skin and VM sensitization, no significant differences were observed in the frequencies of interferon‐γ‐producing CD4⁺ and CD8⁺ effector, and regulatory T cells in dLNs after sensitization. We also observed no significant differences with respect to differentiation of hapten‐specific T cells based on the examination of cytokine production from dLN cells stimulated in vitro with 2,4‐dinitrobenzene sulfonate.

Conclusion

These findings suggested that the lower T cell proliferation after VM sensitization is important for the lower CHS responses with VM sensitization than skin sensitization.

Safety Evaluation of Absorbent Hygiene Pads: A Review on Assessment Framework and Test Methods

Disposable absorbent hygiene products have evolved for superior performance, enhancing the convenience of daily lives. However, the use of disposable hygiene pads has brought safety concerns on chemical exposure, and significant efforts have been made to assess the potential risks associated with use of hygiene pads. This article intends to overview the safety assessment framework of diapers and feminine pads, which includes hazard identification, hazard characterization, exposure assessment, risk characterization, and post-market risk management. Risk assessment of various constituents are reviewed for quantification methods and conservative estimation of exposure parameters. By reviewing the up-to-date considerations in risk assessment, we aim to provide insightful discussion on safety evaluation of current versions of disposable absorbent products. More clinical testing and post-market surveillance are needed for continuous monitoring of potential health impacts of advanced products and constituents.

A Feminine Care Clinical Research Program Transforms Women's Lives

Feminine hygiene products and menstruation education have transformed the lives of women throughout the world. The P&G Feminine Care Clinical Innovation Research Program has played a key role by expanding scientific knowledge as well as developing technical insights and tools for the development of feminine hygiene products. The aim has been to meet the needs of women throughout their life stages, advancing their urogenital health beyond just menstruation, as well as helping to understand the role of sex hormones in various important health issues that women face. This review article highlights key contributions and research findings in female hygiene products, urogenital health research, and method development. The clinical research team focused on utilizing the results of clinical safety studies to advance the acceptance of feminine hygiene products world-wide. Key findings include that perception of skin sensitivity is not limited to the facial area, but is also relevant to the body and the genital area. Also, they shed light on the role of estrogen in autoimmune diseases as well as premenstrual syndrome. Efforts in the method development area focused on innovative tools that are reliable, predictive of clinical trial results and capable of measuring wear comfort, genital skin health, and the impact of product use on the consumer’s quality of life. A novel method, behind-the-knee (BTK) test, developed to model irritation under normal wear conditions, was the first to account for both chemical and mechanical sources of irritation. The method has been accepted by the FDA as a substitute in clinical trials in some cases, and by American Society for Testing and Materials as a global standard test method. Additional proprietary methods were developed to enhance visual grading of irritation using cross-polarized light, to measure the amount of lotion transferred from sanitary pads, and to evaluate the skin mildness. Finally, the Farage Quality of Life tool was created to measure consumer’s well-being. Based on the results of this extensive clinical research and the newly developed testing methods, the changing needs of women throughout their life stages are better met.

Dermal sensitization quantitative risk assessment (QRA) for fragrance ingredients

Based on chemical, cellular, and molecular understanding of dermal sensitization, an exposure-based quantitative risk assessment (QRA) can be conducted to determine safe use levels of fragrance ingredients in different consumer product types. The key steps are: (1) determination of benchmarks (no expected sensitization induction level (NESIL)); (2) application of sensitization assessment factors (SAF); and (3) consumer exposure (CEL) calculation through product use. Using these parameters, an acceptable exposure level (AEL) can be calculated and compared with the CEL. The ratio of AEL to CEL must be favorable to support safe use of the potential skin sensitizer. This ratio must be calculated for the fragrance ingredient in each product type. Based on the Research Institute for Fragrance Materials, Inc. (RIFM) Expert Panel's recommendation, RIFM and the International Fragrance Association (IFRA) have adopted the dermal sensitization QRA approach described in this review for fragrance ingredients identified as potential dermal sensitizers. This now forms the fragrance industry's core strategy for primary prevention of dermal sensitization to these materials in consumer products. This methodology is used to determine global fragrance industry product management practices (IFRA Standards) for fragrance ingredients that are potential dermal sensitizers. This paper describes the principles of the recommended approach, provides detailed review of all the information used in the dermal sensitization QRA approach for fragrance ingredients and presents key conclusions for its use now and refinement in the future.

Do panty liners promote vulvovaginal candidiasis or urinary tract infections? A review of the scientific evidence

Panty liners are used to absorb light menstrual flow, vaginal discharge, or urine leakage, or to maintain a clean, dry feeling. Allegations that panty liners may trap heat and moisture to promote vulvovaginal candidiasis (VVC) or promote colonization by microbes that contribute to urinary tract infections appear to be unfounded. As reviewed herein, measurements of the impact of panty liners on skin temperature and skin surface moisture had no clinically meaningful effect on cell densities of genital microflora. Epidemiological investigations of a potential link to VVC were either negative or were inconclusive because of confounding factors. Although enteric microbes reside on the vulva and perineum, no evidence exists that panty liner use promotes urethral colonization by enteric microbes. Moreover, a series of 13 randomized prospective trials of panty liners or ultra-thin pads demonstrated no clinically significant adverse effects either on the skin or on isolation frequencies or cell densities of representative genital microflora. Post-market surveillance systems suggest a low incidence of complaints. Evidence from vulvar clinic patients reveals no significant contribution of these products to persistent vulvar symptoms. Taken together, the scientific evidence supports the conclusion that panty liners are safe when used as intended and do not promote VVC or urinary tract infections.

The impact of exposure variables on the induction of skin sensitization

Whereas many investigations of the variables associated with the elicitation of allergic contact dermatitis have been undertaken, to the point where we can begin to predict the likelihood of elicitation occurring in a given situation, the same is not true for the induction of skin sensitization. Studies have demonstrated that increasing dose has an impact; in an experimental setting, a number of variables received attention some decades ago. However, in the work reported here, the relative importance of the frequency and the duration of exposure is highlighted. In an investigation using a human repeated insult patch test, it was demonstrated that reduction of the exposure duration from 48 hr to 5 min decreased the rate of sensitization to 1% p-phenylenediamine (PPD) from 54% to 3%. However, in an extended clinical study, it was observed that infrequent but longer duration and higher concentration exposure to PPD was significantly less likely to induce sensitization compared to more frequent, short duration, and lower concentration exposure. Detailed statistical analysis of the results indicated that the most important factor driving the induction of skin sensitization was the number of exposures.

A Behind-the-Scenes Look at the Safety Assessment of Feminine Hygiene Pads

Forms of menstrual protection have evolved with time. Today's disposable feminine hygiene products, notably sanitary pads, include a wide range of designs and features to meet women's needs for reliable, discreet, and comfortable protection. Manufacturers support substantive research and testing programs to ensure the safety of these products. The premarket safety assessment of feminine hygiene pads is a systematic, stepwise process that includes toxicological evaluation of the raw materials, the conduct of prospective, controlled clinical trials to assess product safety-in-use, and, in some cases, independent scientific review. A broad clinical database, developed over the past 20 years, substantiates that modern, feminine hygiene pads are not associated with significant gynecological, dermatological, or microbiological effects. Postmarket surveillance provides reassurance that the products are acceptable to consumers worldwide.

Influence of usage practices, ethnicity and climate on the skin compatibility of sanitary pads

Modern disposable sanitary pads are becoming available worldwide. Regional differences in usage practices, ethnicity, and climate may influence their skin compatibility. Pad usage practices depend on culture, economics, and menstrual physiology. Daily usage is higher in Japan and but lower in Nigeria compared to North America or Western Europe. Evidence for ethnic differences in skin irritant susceptibility is not compelling. Dark skin may be less susceptible to certain irritants than fair skin; the Japanese may experience a higher degree of sensory irritation than Caucasians. Ambient conditions such as high temperature and humidity increase the skin temperature and skin surface moisture under sanitary pads by small but measurable amounts, causing no discernible skin irritation; vapor-permeable pad backings reduce these effects. Cold dry conditions, which can irritate exposed skin, may not affect vulvar skin to the same degree due to its elevated hydration and occlusion. To address the practical significance of these variables, results of prospective clinical trials of sanitary pads performed by industry and academic scientists in North America (Indiana), Mexico, Western Europe (Munich, Athens, Goteborg, Sweden), Eastern Europe (Kiev) and Africa (Abuja, Nigeria) were reviewed. Despite the diverse range of conditions, no significant adverse skin effects were observed with modern pads compared to traditional pad designs. Study participants generally preferred modern pads for performance and comfort.

The vulvar epithelium differs from the skin: implications for cutaneous testing to address topical vulvar exposures

Vulvar tissue is more permeable than exposed skin due to differences in structure, occlusion, hydration and susceptibility to friction. The safety assessment of products that contact the vulva should account for this potentially heightened permeability. Standard clinical patch tests may not sufficiently mimic vulvar exposures. Because testing on the vulva is not routinely feasible, we are investigating new and modified cutaneous test methods to increase the degree of conservatism of the safety assessment. To this end, we have 1) developed a method to assess chemical and frictional effects by means of repeated application to the popliteal fossa (the behind-the-knee test); 2) modified the quantitative risk assessment for the induction of allergic contact dermatitis; and 3) proposed a modified human repeat insult patch test for assessing materials intended for vulvar contact. Modification of the traditional 4-day, irritation patch test by using wet samples or compromized skin sites failed to enhance test sensitivity. Future studies will evaluate testing in subjects with heightened susceptibility to chemical and sensory irritation, in order to increase test sensitivity to chemical irritants. These approaches can be employed to augment the margin of safety when cutaneous test methods are applied to agents that contact the vulva.