Photopatch Testing in New Zealand: A 12-Year Retrospective Review

A review of sources, pathways, and toxic effects of human exposure to benzophenone ultraviolet light filters

Benzophenone ultraviolet light filters (BPs) are high-production-volume chemicals extensively used in personal care products, leading to widespread human exposure. Given their estrogenic properties, the potential health risks associated with exposure to BPs have become a public health concern. This review aims to summarize sources and pathways of exposure to BPs and associated health risks. Dermal exposure, primarily through the use of sunscreens, constitutes a major pathway for BP exposure. At a recommended application rate, dermal exposure of BP-3 via the application of sunscreens may reach or exceed the suggested reference dose. Other exposure pathways to BPs, such as drinking water, seafood, and packaged foods, contribute minimal to the overall dose. Inhalation is a minor pathway of exposure; however, its contribution cannot be ignored. Human exposure to BPs is an order of magnitude higher in North America than in Asia and Europe. Studies conducted on laboratory animals and cells have consistently demonstrated the toxic effects of BP exposure. BPs are estrogenic and elicit reproductive and developmental toxicities. Furthermore, neurotoxicity, hepatotoxicity, nephrotoxicity, and carcinogenicity have been reported from chronic BP exposure. In addition to animal and cell studies, epidemiological investigations have identified associations between BPs and couples' fecundity and other reproductive disorders, as well as adverse birth outcomes. Further studies are urgently needed to understand the risks posed by BPs on human health.

Patch Testing With Benzophenone-3 and -4: The North American Contact Dermatitis Group Experience, 2013-2020

Background: Benzophenone (BZP)-3 and BZP-4 are ultraviolet (UV) absorbers used in sunscreens and personal care products (PCPs) and may cause allergic contact dermatitis. Objective: To characterize positive patch test reactions to BZP-3 (10% in petrolatum [pet]) and BZP-4 (2% pet) in a screening allergen series. Methods: Retrospective analysis of patients tested to BZP-3 and BZP-4 was conducted by the North American Contact Dermatitis Group from 2013 to 2020. Results: Of 19,618 patients patch tested to BZP-3 and BZP-4, 103 (0.5%) and 323 (1.6%) had positive reactions, respectively: 413 (2.1%) reacted to at least 1 BZP (BZP-positive patient). As compared with BZP-negative patients, BZP-positive patients were significantly more likely to have a history of hay fever (39.3% vs 33.4%, P = 0.0134), history of atopic dermatitis (39.8% vs 30.7%, P = 0.0001), and facial involvement (37.4% vs 32.2%, P = 0.0272). Most reactions were currently clinically relevant (BZP-3: 90.4%; BZP-4: 65.8%). Common identified sources included PCPs and sunscreens. Coreactivity between BZP-3 and BZP-4 was low: 13.5% (14/104) of BZP-3-positive patients were allergic to BZP-4 and 4.3% (14/322) of BZP-4-positive patients were allergic to BZP-3. Conclusions: Eight-year prevalence of BZP positivity was 2.1%. Reactions were frequently clinically relevant and linked to PCPs and sunscreens.

Ultraviolet filter, fragrance and preservative allergens in New Zealand sunscreens

BACKGROUND/OBJECTIVES

Allergic contact dermatitis, photoallergic contact dermatitis and irritant reactions to sunscreens are common reasons for dermatology consultation. Patch testing for contact allergy relies on up-to-date knowledge of allergen exposures. The aim of this study was to investigate contact allergens and photoallergens in sunscreens commercially sold on the shelves of supermarkets and pharmacies in New Zealand.

METHODS

A comprehensive market data review of suppliers' websites was performed from March to August 2019 to obtain a list of the commonly sold sunscreens in our region. Ingredients were collated and analysed according to International Nomenclature of Cosmetic Ingredients (INCI) names. Ultraviolet (UV) filters, preservatives and fragrances were included for analysis. Place of sale and cost of sunscreens were also recorded.

RESULTS

Ninety-five sunscreens were analysed: 36% sold in supermarkets, 43% in pharmacies and the remainder available in both. The most frequent UV filters were butyl methoxydibenzoylmethane (contained in 70% of products) followed by octocrylene (63%) and homosalate (50%). The common photoallergen benzophenone 3 was found in 19% of products. Phenoxyethanol was the most common preservative (68%) followed by disodium EDTA (30%) and propylparaben (26%). Two sunscreens contained methylisothiazolinone. Sixty-one per cent contained at least one fragrance, the most frequent being limonene (17%) and linalool (13%). There was an average of 1.1 New Zealand baseline series allergens per product (range 0 to 6, standard deviation 1.27).

CONCLUSION

Common allergens including those with high sensitising potential were frequently found in New Zealand sunscreen. Knowledge of ingredients used by manufacturers is useful in dermatological assessment of skin contact reactions.