Australian therapeutic sunscreens are multi-filter mixtures: Single-ingredient margin of safety assessment does not address cumulative exposure.

Authors

Abhinandan Chowdhury, Joseph Mizikovsky

Published in

Toxicology reports. Volume 17. Pages 102326. Epub Aug 09, 2026.

Abstract

Australian sunscreens are regulated as therapeutic goods and recommended for daily whole-body application. Yet, the multi-filter formulations actually on sale have not previously been characterised at the population level. We extracted all therapeutic sunscreens with active AUST L designation from the Australian Register of Therapeutic Goods (ARTG) and analysed their UV filter combinations, concentrations and prevalence. After deduplication and removal of non-sunscreen items, 924 unique products remained. Of these, 187 (20.2%) were mineral-only sunscreens with no organic UV filter declared. The remaining 737 (79.8%) contained organic filters, all in combinations of two or more: 45.7% contained four organic filters, 85.2% four or more, and 39.5% five or more. Combined organic UV filter loads commonly reached 15-25% w/w of the total formulation. Twenty filter actives were identified; the market was dominated by avobenzone (641), octocrylene (600), octyl salicylate (411), homosalate (410) and zinc oxide (243). A targeted review of nine recurring organic filters identified three structural problems in the current single-ingredient Margin of Safety (MoS) assessment: shared endocrine targets, photochemical and oxidative-stress mechanisms that produce additive transformation products, and co-formulation with documented dermal penetration enhancers. None of these effects are summed across co-formulated filters in any current safety assessment. Non-dermal exposure pathways, including indoor air, indoor dust, human milk and chlorinated water, are likewise excluded. Single-ingredient MoS assessment does not account for cumulative exposure in these multi-filter products. The resulting cumulative risk remains uncharacterised. A pathway and mixture-based evaluation framework is feasible.

PMID:
42633302
Bibliographic data and abstract were imported from PubMed on 23 Aug 2026.

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