Understanding fragrance allergy using an exposure-based risk assessment approach

Biocidal products: Opportunities in risk assessment, management, and communication

In the coronavirus disease 2019 era, biocidal products are increasingly used for controlling harmful organisms, including microorganisms. However, assuring safety against adverse health effects is a critical issue from a public health standpoint. This study aimed to provide an overview of key aspects of risk assessment, management, and communication that ensure the safety of biocidal active ingredients and products. The inherent characteristics of biocidal products make them effective against pests and pathogens; however, they also possess potential toxicities. Therefore, public awareness regarding both the beneficial and potential adverse effects of biocidal products needs to be increased. Biocidal active ingredients and products are regulated under specific laws: the Federal Insecticide, Fungicide, and Rodenticide Act for the United States; the European Union (EU) Biocidal Products Regulation for the EU; and the Consumer Chemical Products and Biocide Safety Management Act for the Republic of Korea. Risk management also needs to consider the evidence of enhanced sensitivity to toxicities in individuals with chronic diseases, given the increased prevalence of these conditions in the population. This is particularly important for post-marketing safety assessments of biocidal products. Risk communication conveys information, including potential risks and risk-reduction measures, aimed at managing or controlling health or environmental risks. Taken together, the collaborative effort of stakeholders in risk assessment, management, and communication strategies is critical to ensuring the safety of biocidal products sold in the market as these strategies are constantly evolving.

TFOS Lifestyle: Impact of elective medications and procedures on the ocular surface

The word "elective" refers to medications and procedures undertaken by choice or with a lower grade of prioritization. Patients usually use elective medications or undergo elective procedures to treat pathologic conditions or for cosmetic enhancement, impacting their lifestyle positively and, thus, improving their quality of life. However, those interventions can affect the homeostasis of the tear film and ocular surface. Consequently, they generate signs and symptoms that could impair the patient's quality of life. This report describes the impact of elective topical and systemic medications and procedures on the ocular surface and the underlying mechanisms. Moreover, elective procedures performed for ocular diseases, cosmetic enhancement, and non-ophthalmic interventions, such as radiotherapy and bariatric surgery, are discussed. The report also evaluates significant anatomical and biological consequences of non-urgent interventions to the ocular surface, such as neuropathic and neurotrophic keratopathies. Besides that, it provides an overview of the prophylaxis and management of pathological conditions resulting from the studied interventions and suggests areas for future research. The report also contains a systematic review investigating the quality of life among people who have undergone small incision lenticule extraction (SMILE). Overall, SMILE refractive surgery seems to cause more vision disturbances than LASIK in the first month post-surgery, but less dry eye symptoms in long-term follow up.

Assessing the risk of induction of skin sensitization to plant protection products: A quantitative approach

Exposure to skin sensitizers is common and regulated in many industry sectors. For cosmetics, a risk-based approach has been implemented, focused on preventing the induction of sensitization. First, a No Expected Sensitization Induction Level (NESIL) is derived, then modified by Sensitization Assessment Factors (SAFs) to derive an Acceptable Exposure Level (AEL). The AEL is used in risk assessment, being compared with an estimated exposure dose, specific to the exposure scenario. Since in Europe there is increased concern regarding exposure towards potentially sensitizing pesticides via spray drift, we explore how existing practice can be modified to allow Quantitative Risk Assessment (QRA) of pesticides for bystanders and residents. NESIL derivation by the Local Lymph Node Assay (LLNA), the globally required in vivo assay for this endpoint, is reviewed alongside consideration of appropriate SAFs. Using a case study, the principle that the NESIL in μg/cm² can be derived by multiplying LLNA EC3% figure by a factor of 250 is adopted. The NESIL is then reduced by an overall SAF of 25 to establish an exposure level below which there is minimal bystander and resident risk. Whilst this paper focuses on European risk assessment and management, the approach is generic and universally applicable.

Current trends in read-across applications for chemical risk assessments and chemical registrations in the Republic of Korea

Read-across, an alternative approach for hazard assessment, has been widely adopted when in vivo data are unavailable for chemicals of interest. Read-across is enabled via in silico tools such as quantitative structure activity relationship (QSAR) modeling. In this study, the current status of structure activity relationship (SAR)-based read-across applications in the Republic of Korea (ROK) was examined considering both chemical risk assessments and chemical registrations from different sectors, including regulatory agencies, industry, and academia. From the regulatory perspective, the Ministry of Environment (MOE) established the Act on Registration and Evaluation of Chemicals (AREC) in 2019 to enable registrants to submit alternative data such as information from read-across instead of in vivo data to support hazard assessment and determine chemical-specific risks. Further, the Ministry of Food and Drug Safety (MFDS) began to consider read-across approaches for establishing acceptable intake (AI) limits of impurities occurring during pharmaceutical manufacturing processes under the ICH M7 guideline. Although read-across has its advantages, this approach also has limitations including (1) lack of standardized criteria for regulatory acceptance, (2) inconsistencies in the robustness of scientific evidence, and (3) deficiencies in the objective reliability of read-across data. The application and acceptance rate of read-across may vary among regulatory agencies. Therefore, sufficient data need to be prepared to verify the hypothesis that structural similarities might lead to similarities in properties of substances (between source and target chemicals) prior to adopting a read-across approach. In some cases, additional tests may be required during the registration process to clarify long-term effects on human health or the environment for certain substances that are data deficient. To improve the quality of read-across data for regulatory acceptance, cooperative efforts from regulatory agencies, academia, and industry are needed to minimize limitations of read-across applications.

RIFM fragrance ingredient safety assessment, 3-Cyclohexene-1-carboxaldehyde, 1-ethenyl-, CAS Registry Number 1049017-63-1

The existing information supports the use of this material as described in this safety assessment. 3-Cyclohexene-1-carboxaldehyde, 1-ethenyl- was evaluated for genotoxicity, repeated dose toxicity, reproductive toxicity, local respiratory toxicity, phototoxicity/photoallergenicity, skin sensitization, and environmental safety. Data show that 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- is not genotoxic. Data on 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- provide a calculated Margin of Exposure (MOE) > 100 for the repeated dose toxicity endpoint. The reproductive and local respiratory toxicity endpoints were evaluated using the Threshold of Toxicological Concern (TTC) for a Cramer Class I material, and the exposure to 3-cyclohexene-1-carboxaldehyde, 1-ethenyl-is below the TTC (0.03 mg/kg/day and 1.4 mg/day, respectively). Data provided 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- a No Expected Sensitization Induction Level (NESIL) of 1000 μg/cm² for the skin sensitization endpoint. The phototoxicity/photoallergenicity endpoints were evaluated based on ultraviolet/visible (UV/Vis) spectra; 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- is not expected to be phototoxic/photoallergenic. The environmental endpoints were evaluated; 3-cyclohexene-1-carboxaldehyde, 1-ethenyl- was found not to be Persistent, Bioaccumulative, and Toxic (PBT) as per the International Fragrance Association (IFRA) Environmental Standards, and its risk quotients, based on its current volume of use in Europe and North America (i.e., Predicted Environmental Concentration/Predicted No Effect Concentration [PEC/PNEC]), are <1.

Implementation of a dermal sensitization threshold (DST) concept for risk assessment: structure-based DST and in vitro data-based DST

Skin sensitization resulting in allergic contact dermatitis represents an important toxicological endpoint as part of safety assessments. When available substance-specific sensitization data are inadequate, the dermal sensitization threshold (DST) concept has been proposed to set a skin exposure threshold to provide no appreciable risk of skin sensitization. Structure-based DSTs, which include non-reactive, reactive, and high potency category (HPC) DSTs, can be applied to substances with an identified chemical structures. An in vitro data-based "mixture DST" can be applied to mixtures based on data from in vitro test methods, such as KeratinoSens™ and the human Cell Line Activation Test. The purpose of this review article is to discuss the practical use of DSTs for conducting sound sensitization risk assessments to assure the safety of consumer products. To this end, several improvements are discussed in this review. For application of structure-based DSTs, an overall structural classification workflow was developed to exclude the possibility that "HPC but non-reactive" chemicals are misclassified as "non-reactive", because such chemicals should be classified as HPC chemicals considering that HPC rules have been based on the chemical structure of high potency sensitizers. Besides that, an extended application of the mixture DST principle to mixtures that either is cytotoxic or evaluated as positive was proposed. On a final note, we also developed workflows that integrate structure-based and in vitro-based mixture DST. The proposed workflows enable the application of the appropriate DST, which serves as a point of departure in the quantitative sensitization risk assessment.

Skin Sensitization Testing: The Ascendancy of Non-Animal Methods

A century ago, toxicology was an empirical science identifying substance hazards in surrogate mammalian models. Over several decades, these models improved, evolved to reduce animal usage, and recently have begun the process of dispensing with animals entirely. However, despite good hazard identification, the translation of hazards into adequately assessed risks to human health often has presented challenges. Unfortunately, many skin sensitizers known to produce contact allergy in humans, despite being readily identified as such in the predictive assays, continue to cause this adverse health effect. Increasing the rigour of hazard identification is inappropriate. Regulatory action has only proven effective via complete bans of individual substances. Since the problem applies to a broad range of substances and industry categories, and since generic banning of skin sensitizers would be an economic catastrophe, the solution is surprisingly simple—they should be subject to rigorous safety assessment, with the risks thereby managed accordingly. The ascendancy of non-animal methods in skin sensitization is giving unparalleled opportunities in which toxicologists, risk assessors, and regulators can work in concert to achieve a better outcome for the protection of human health than has been delivered by the in vivo methods and associated regulations that they are replacing.

Next generation risk assessment for skin allergy: Decision making using new approach methodologies

Our aim is to develop and apply next generation approaches to skin allergy risk assessment (SARA) that do not require new animal test data and better quantify uncertainties. Significant progress has been made in the development of New Approach Methodologies (NAMs), non-animal test methods, for assessment of skin sensitisation and there is now focus on their application to derive potency information for use in Next Generation Risk Assessment (NGRA). The SARA model utilises a Bayesian statistical approach to infer a human-relevant metric of sensitiser potency and a measure of risk associated with a given consumer exposure based upon any combination of human repeat insult patch test, local lymph node, direct peptide reactivity assay, KeratinoSens™, h-CLAT or U-SENS™ data. Here we have applied the SARA model within our weight of evidence NGRA framework for skin allergy to three case study materials in four consumer products. Highlighting how to structure the risk assessment, apply NAMs to derive a point of departure and conclude on consumer safety risk. NGRA based upon NAMs were, for these exposures, at least as protective as the historical risk assessment approaches. Through such case studies we are building our confidence in using NAMs for skin allergy risk assessment.

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.

Adjustment of a no expected sensitization induction level derived from Bayesian network integrated testing strategy for skin sensitization risk assessment

Skin sensitization is a key adverse effect to be addressed during hazard identification and risk assessment of chemicals, because it is the first step in the development of allergic contact dermatitis. Multiple non-animal testing strategies incorporating in vitro tests and in silico tools have achieved good predictivities when compared with murine local lymph node assay (LLNA). The binary test battery of KeratinoSens^TM and h-CLAT could be used to classify non-sensitizers as the first part of bottom-up approach. However, the quantitative risk assessment for sensitizing chemicals requires a No Expected Sensitization Induction Level (NESIL), the dose not expected to induce skin sensitization in humans. We used Bayesian network integrated testing strategy (BN ITS-3) for chemical potency classification. BN ITS-3 predictions were performed without a pre-processing step (selecting data from their physic-chemical applicability domains) or post-processing step (Michael acceptor chemistry correction), neither of which necessarily improve prediction accuracy. For chemicals within newly defined applicability domain, all under-predictions fell within one potency class when compared with LLNA results, indicating no chemicals that were incorrectly classified by more than one class. Considering the potential under-prediction by one class, a worst case value to each class from BN ITS-3 was used to derive a NESIL. When in vivo and human data from suitable analogs cannot be used to estimate the uncertainty, adjusting the NESIL derived from BN ITS-3 may help perform skin sensitization risk assessment. The overall workflow for risk assessment was demonstrated by incorporating the binary test battery of KeratinoSens^TM and h-CLAT.

European Surveillance System on Contact Allergies (ESSCA): Contact allergies in relation to body sites in patients with allergic contact dermatitis

Background

Analyses of the European Surveillance System on Contact Allergies (ESSCA) database have focused primarily on the prevalence of contact allergies to the European baseline series, both overall and in subgroups of patients. However, affected body sites have hitherto not been addressed.

Objective

To determine the prevalence of contact allergies for distinct body sites in patients with allergic contact dermatitis (ACD).

Methods

Analysis of data collected by the ESSCA (www.essca‐dc.org) in consecutively patch tested patients, from 2009 to 2014, in eight European countries was performed. Cases were selected on the basis of the presence of minimally one positive patch test reaction to the baseline series, and a final diagnosis of ACD attributed to only one body site.

Results

Six thousand two hundred and fifty‐five cases were analysed. The head and hand were the most common single sites that ACD was attributed to. Differences between countries were seen for several body sites. Nickel, fragrance mix I, cobalt and methylchloroisothiazolinone/methylisothiazolinone were the most frequent allergens reported for various body sites.

Conclusions

Distinct allergen patterns per body site were observed. However, contact allergies were probably not always relevant for the dermatitis that patients presented with. The possibility of linking positive patch test reactions to relevance, along with affected body sites, should be a useful addition to patch test documentation systems.

Percutaneous permeability of 1-phenoxy-2-propanol, a preservative in cosmetics

1-Phenoxy-2-propanol (PP) is used as a preservative in cosmetics. PP is currently permitted to be used to up to 1% in cosmetic formulations in Korea and Europe. For risk assessment, percutaneous absorption is a crucial factor, but dermal absorption of PP has not yet been reported. In this study, Franz diffusion method was used to determine the percutaneous penetration of PP using the dorsal skin of rats. Each formulation of shampoo or cream, 113.6 mg/cm², was applied to a donor compartment of Franz diffusion cell for 24 h. Receptor fluid was collected at 0, 1, 2, 4, 8, 12, and 24 h following dermal application. Remaining formulation was removed with a cotton swab after last sampling. Using tape stripping method, stratum corneum was removed. PP in epidermis and dermis was extracted in PBS for 24 h. The concentration of PP from the swab, stratum corneum, and epidermis and dermis samples was determined using high performance liquid chromatography. Total percutaneous absorption rates of PP for shampoo and cream were 50.0 ± 6.0% and 33.0 ± 3.2%, respectively. In vitro skin permeability was calculated as 1,377.2 ± 240.1 mg/cm² for shampoo and 1,038.0 ± 72.2 mg/cm² for cream for 24 h.

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.

Fragrances Categorized According to Relative Human Skin Sensitization Potency

Background

The development of non-animal alternatives for skin sensitization potency prediction is dependent upon the availability of a sufficient dataset whose human potency is well characterized. Previously, establishment of basic categorization criteria for 6 defined potency categories, allowed 131 substances to be allocated into them entirely on the basis of human information.

Objectives

To supplement the original dataset with an extended range of fragrance substances.

Methods

A more fully described version of the original criteria was used to assess 89 fragrance chemicals, allowing their allocation into one of the 6 potency categories.

Results

None of the fragrance substances were assigned to the most potent group, category 1, whereas 11 were category 2, 22 were category 3, 37 were category 4, and 19 were category 5. Although none were identified as non-sensitizing, note that substances in category 5 also do not pass the threshold for regulatory classification.

Conclusions

The combined datasets of >200 substances placed into potency categories solely on the basis of human data provides an essential resource for the elaboration and evaluation of predictive non-animal methods.

Commercial Essential Oils as Potential Antimicrobials to Treat Skin Diseases

Essential oils are one of the most notorious natural products used for medical purposes. Combined with their popular use in dermatology, their availability, and the development of antimicrobial resistance, commercial essential oils are often an option for therapy. At least 90 essential oils can be identified as being recommended for dermatological use, with at least 1500 combinations. This review explores the fundamental knowledge available on the antimicrobial properties against pathogens responsible for dermatological infections and compares the scientific evidence to what is recommended for use in common layman's literature. Also included is a review of combinations with other essential oils and antimicrobials. The minimum inhibitory concentration dilution method is the preferred means of determining antimicrobial activity. While dermatological skin pathogens such as Staphylococcus aureus have been well studied, other pathogens such as Streptococcus pyogenes, Propionibacterium acnes, Haemophilus influenzae, and Brevibacterium species have been sorely neglected. Combination studies incorporating oil blends, as well as interactions with conventional antimicrobials, have shown that mostly synergy is reported. Very few viral studies of relevance to the skin have been made. Encouragement is made for further research into essential oil combinations with other essential oils, antimicrobials, and carrier oils.

Bayesian integrated testing strategy (ITS) for skin sensitization potency assessment: a decision support system for quantitative weight of evidence and adaptive testing strategy

The presented Bayesian network Integrated Testing Strategy (ITS-3) for skin sensitization potency assessment is a decision support system for a risk assessor that provides quantitative weight of evidence, leading to a mechanistically interpretable potency hypothesis, and formulates adaptive testing strategy for a chemical. The system was constructed with an aim to improve precision and accuracy for predicting LLNA potency beyond ITS-2 (Jaworska et al., J Appl Toxicol 33(11):1353-1364, 2013) by improving representation of chemistry and biology. Among novel elements are corrections for bioavailability both in vivo and in vitro as well as consideration of the individual assays' applicability domains in the prediction process. In ITS-3 structure, three validated alternative assays, DPRA, KeratinoSens and h-CLAT, represent first three key events of the adverse outcome pathway for skin sensitization. The skin sensitization potency prediction is provided as a probability distribution over four potency classes. The probability distribution is converted to Bayes factors to: 1) remove prediction bias introduced by the training set potency distribution and 2) express uncertainty in a quantitative manner, allowing transparent and consistent criteria to accept a prediction. The novel ITS-3 database includes 207 chemicals with a full set of in vivo and in vitro data. The accuracy for predicting LLNA outcomes on the external test set (n = 60) was as follows: hazard (two classes)-100 %, GHS potency classification (three classes)-96 %, potency (four classes)-89 %. This work demonstrates that skin sensitization potency prediction based on data from three key events, and often less, is possible, reliable over broad chemical classes and ready for practical applications.

Skin sensitization

Skin sensitization associated with allergic contact dermatitis is a common health problem and is an important consideration for toxicologists in safety assessment. Historically, in vivo predictive tests have been used with good success to identify substances that have the potential to induce skin sensitization, and these tests formed the basis of safety evaluation. These original tests are now being replaced gradually either by in vitro assays or by further refinements of in vivo methods such as the local lymph node assay. Human data have also been available to inform classification decisions for some substances and have been used by risk managers to introduce measures for exposure reduction. However, humans encounter hazards in the context of exposure rather than in the form of intrinsic hazards per se, and so in this article, we have examined critically the extent to which human data have been used to refine classification decisions and safety evaluations. We have also evaluated information on the burden of human allergic skin disease and used this to address the question of whether, and to what extent, the identification and evaluation of skin sensitization hazards has led to an improvement of public and/or occupational health.

Consideration of criteria required for assignment of a (skin) sensitiser a substance of very high concern (SVHC) under the REACH regulation

The identification, characterisation, risk assessment and risk management of materials that cause allergic sensitisation is an important requirement for human health protection. It has been proposed that for some chemical and protein allergens, and in particular for those that cause sensitisation of the respiratory tract (associated with occupational asthma), it may be appropriate to regard them as Substances of Very High Concern (SVHC) under the provisions of REACH (Registration, Evaluation, Authorisation and restriction of CHemicals). We have argued previously that categorisation of sensitising agents as SVHC should be used only in exceptional circumstances. In the present article, the subject of SVHC is addressed from another perspective. Here the information that would be required to provide a compelling case for categorisation of a skin sensitising substance as a SVHC is considered. Three skin sensitising chemicals have been identified to serve as working examples. These are chromate, a potent contact allergen, and the skin sensitisers formaldehyde and isoeugenol. The key criterion influencing the decision regarding a skin sensitiser being categorised as SVHC is the extent to which impacts on the quality of life are reversible. Consequently, SVHC categorisation for skin sensitising chemicals should be used only in exceptional circumstances.

The science of dermocosmetics and its role in dermatology

Our increased knowledge of normal skin physiology has ushered in a subtle revolution in cosmetic science. Originally designed as preparations to enhance personal appearance by direct application on to the skin, cosmetics have now taken on a new role in dermatology, through the support of the management of many skin disorders. This evolving role of cosmetics in skin care is primarily due to scientific and technological advancements that have changed our understanding of normal skin physiology and how cosmetics modify its appearance both physically and biologically. The vast array of techniques currently available to investigate skin responsivity to multiple stimuli has brought about a new era in cosmetic and dermocosmetic development based on a robust understanding of skin physiology and its varied responses to commonly encountered environmental insults. Most cosmetic research is undertaken on reconstructed skin models crucial in dermatological research, given the strict ban imposed by the European Union on animal testing. In addition, the design and conduct of trials evaluating cosmetics now follow rules comparable to those used in the development and evaluation of pharmaceutical products. Cosmetic research should now aim to ensure all trials adhere to strictly reproducible and scientifically sound methodologies. The objective of this review is to provide an overview of the multidisciplinary scientific approach used in formulating dermocosmetics, and to examine the major advances in dermocosmetic development and assessment, the safety and regulatory guidelines governing their production and the exciting future outlook for these dermocosmetic processes following good practice rules.

Guiding principles for the implementation of non-animal safety assessment approaches for cosmetics: skin sensitisation

Characterisation of skin sensitisation potential is a key endpoint for the safety assessment of cosmetic ingredients especially when significant dermal exposure to an ingredient is expected. At present the mouse local lymph node assay (LLNA) remains the 'gold standard' test method for this purpose however non-animal test methods are under development that aim to replace the need for new animal test data. COLIPA (the European Cosmetics Association) funds an extensive programme of skin sensitisation research, method development and method evaluation and helped coordinate the early evaluation of the three test methods currently undergoing pre-validation. In May 2010, a COLIPA scientific meeting was held to analyse to what extent skin sensitisation safety assessments for cosmetic ingredients can be made in the absence of animal data. In order to propose guiding principles for the application and further development of non-animal safety assessment strategies it was evaluated how and when non-animal test methods, predictions based on physico-chemical properties (including in silico tools), threshold concepts and weight-of-evidence based hazard characterisation could be used to enable safety decisions. Generation and assessment of potency information from alternative tools which at present is predominantly derived from the LLNA is considered the future key research area.

Allergic contact dermatitis: epidemiology, molecular mechanisms, in vitro methods and regulatory aspects. Current knowledge assembled at an international workshop at BfR, Germany

Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German ‘Federal Institute for Risk Assessment’ hosted an ‘International Workshop on Contact Dermatitis’. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15–20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed.