Allergic contact dermatitis associated with rubber‐based cosmetic sponge

Cases of allergic contact dermatitis (ACD) to cosmetic sponges typically occurring from rubber accelerators have been reported but remain rare.1-4 A 40-year-old female was referred to our Contact Dermatitis Clinic with a 6-month history of worsening facial rash and oedema, most pronounced over bilateral malar medial cheeks (Figure 1). Patient reported the onset of rashes was preceded by the application of a wide range of cosmetics. Relevant past history includes a 20-year history of undiagnosed facial rash of fluctuating severity, and episodes of severe patchy hand dermatitis thought to be a result of a delayed reaction to rubber from rubber gloves while working at a food processing factory several years ago. Examination showed scaling and itchy plaques mainly on the cheeks bilaterally and minimally on the nose, upper lip and forehead, while the hands were clear. The patient was patch tested on the Australian Baseline Series, cosmetic series, fragrance series and common sunscreen series obtained from Chemotechnique Diagnostics (Vellinge, Sweden). She was also patch tested with 23 of her own cosmetic products ‘as is’. The allergens were fixed to the skin with AllergEAZE test chambers (SmartPractice, Calgary, Canada). The occlusion time was 48 h. Readings were performed according to the International Contact Dermatitis Research Group guidelines on Days 2 and 4. Positive readings were noted for to thiuram mix (++) and carba mix (++), as well as for potassium dichromate (+) and abitol (+) on Day 4. Only the rubber allergens were deemed relevant reactions. While discussing the results, she recalled the rashes only appeared after she used rubber-based sponge applicators and not when cosmetics were applied with her hands. A diagnosis of ACD due to rubber accelerators [thiurams, carbamates and/or 1,3-diphenylguanidine (DPG)] in the cosmetic sponge was suspected. The patient was not patch tested on the sponge and we were unable to obtain the sponge's ingredient information. However, given the clinical correlation, we advised her not to use cosmetic applicator sponges. The patient reported significant improvements in her facial dermatitis after completely avoiding use of cosmetic sponges when reviewed 4 months later. In the pre-patch test assessment of this patient, we were dubious about whether contact allergy to particular ingredient(s) would explain her history of reacting to a large number of facial cosmetics over many years as the probability that particular allergen(s) would be found in all of these products is small. Possible exceptions here include allergens widely found in cosmetic products such as fragrances, parabens and cetearyl alcohol,5 none of which were positive in this patient. Patients too can be poly-reactors to many unrelated allergens. Sensitive skin syndrome (a poorly understood phenomenon) is another possible explanation but this usually occurs shortly after application of a wide range of products.6 This patient gave a clear history of reactions delayed many hours after application of the cosmetics as anticipated for ACD. Thiurams, carbamates and/or DPG are rubber accelerators whose purpose is to cross-link rubber polymers to create an elastic compound. They are used in products based on natural rubber latex or in synthetic rubbers like nitrile and neoprene.7 There have been significant advancements in rubber manufacturing technology that allow for production of accelerator-free products but their use to date is quite limited.8 ACD to rubber accelerators continues to be a common problem. Cosmetic sponges tend to be overlooked as a potentially allergenic product despite their widespread use in the beauty industry and by consumers. It is not possible to identify the exact chemical composition of synthetic sponges as consumer law does not mandate discosure of their composition.9 Another example of this is a case of ACD to methylisothiazolinone in a ‘100% natural’ cosmetic sponge.10 This adds an additional layer of difficulty for patients to determine the safety of the products. In conclusion, our case highlights the importance of considering cosmetic sponges as a cause for facial dermatitis patients, particularly when none of their cosmetics returns a positive patch test reading. Sangho Lee: Writing – original draft; data curation; visualization. Kajal Patel: Writing – review and editing; supervision; conceptualization; data curation. Matthew Howard: Conceptualization; supervision; writing – review and editing; data curation; methodology; investigation. Bruce Tate: Conceptualization; writing – review and editing; supervision; validation. There is no conflict of interest to declare. Open access publishing facilitated by Monash University, as part of the Wiley - Monash University agreement via the Council of Australian University Librarians. A formal written consent has been obtained from the patient regarding the use of a photograph which may show them in a recognisable fashion in this publication.

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