Dear members,

We hope these recent publications will be of interest:

Isothiazolinones in Disposable Rubber Gloves-Results of Chemical Analysis
Suuronen K, Ylinen K, Suomela S, Pesonen M. Contact Dermatitis. 2026 Jan 15. doi: 10.1111/cod.70087. Epub ahead of print. PMID: 41540775.

Suuronen et al report findings of chemical analysis to identify isothiazolinones in a total of 52 disposable rubber gloves from patients with hand eczema in an occupational dermatology clinic. Benzisothiazolinone (BIT) was detected in 30/52 gloves (60%), predominantly nitrile, in concentrations of 0.3-73.7ppm (median 4.2ppm, average 12.7ppm). Methylisothiazolinone (MI) was found in 6 (13%) gloves, at low concentrations of 0.8-16.6ppm (median 8.4ppm, average 8.1ppm). None of the gloves contained detectable octyl-, or methylchloro- or dichloroctylisothiazolinone. Patch testing with patients’ own gloves (as is and/or ultrasonic extracts) were frequently negative or equivocal despite measurable BIT/MI. The authors conclude that disposable rubber gloves, including “accelerator-free” nitrile types, may be a clinically relevant hidden isothiazolinone exposure, although did identify other sources of isothiazolinone contact in many of the patients in this cohort.

Changes in Contact Dermatitis Allergen Profile in Chronic Actinic Dermatitis: Results From a Single Centre
Teo YX, Cunningham L, Fassihi H, Sarkany R, White IR, Fityan A. Contact Dermatitis. 2025 Dec 21. doi: 10.1111/cod.70073. Epub ahead of print. PMID: 41423722.

In this single-centre retrospective study, patch test results of 309 chronic actinic dermatitis (CAD) tested between 2011-2021 were examined. 186 (60.2%) had at least one positive reaction, with only 8 (2.6%) testing positive on photo-patch test. Patch test positivity was more likely in patients >40 years and in those with Fitzpatrick phototype V-VI. Sesquiterpene lactones (6.8%) and formaldehyde (4.8%) were amongst the top 10 most frequently positive allergens in CAD but not in non-CAD patients. Compared with earlier cohorts from the same centre (1987-1992 and 2000-2005), both overall patch test positivity and photo-patch positivity have progressively fallen, alongside declining reactions to historically CAD-associated allergens such as sesquiterpene lactone mix. This suggests evolving environmental and lifestyle exposures, whilst supporting the continued role of patch and photo-patch testing in CAD assessment.

Two Cases of Allergic Contact Dermatitis Caused by Coco Betaine in Clobetasol Propionate Shampoo.
Iijima S, Murayama K, Takayama N, Sugiyama M, Matsunaga K. Case Rep Dermatol Med. 2026 Jan 2;2026:9953943. doi: 10.1155/crdm/9953943.

This case report describes two Japanese men (aged 49 and 52) with severe atopic dermatitis on long-term ciclosporin who developed recalcitrant scalp dermatitis following the use of clobetasol propionate (CP) shampoo. Patch testing showed positive reactions to coco betaine 1% aq in both cases. The first patient also had positive reactions to the related amidopropyl betaines (cocamidopropyl betaine and lauramidopropyl betaine) whereas the second patient had doubtful reactions. Dimethylaminopropylamine (DMAPA) and lauramidopropyl dimethylamine (LAPDMA) were negative in the first patient and not tested in the second. Both patients were negative to clobetasol propionate. Symptoms improved markedly after discontinuing the shampoo. The authors highlight potential cross-reactivity or concomitant sensitisation among betaine surfactants, the possibility of suppressed or delayed patch test responses in steroid-containing products, and the need to consider excipients and select alternative “non-allergenic” shampoos carefully in persistent scalp dermatitis.

Allergic Contact Dermatitis to Trimethylpentanediol/Adipic Acid/Glycerin Crosspolymer in a Lip Balm
Lockmann A, Schill T, Schubert S, Buhl T. Contact Dermatitis. 2026 Jan;94(1):95-97. doi: 10.1111/cod.70040. Epub 2025 Oct 26. PMID: 41139661.

This case report describes the first reported case of allergic contact dermatitis to trimethylpentanediol/adipic acid/glycerin crosspolymer (TMPD-AA-GC), a film-forming agent and skin conditioning cosmetic ingredient considered to have a low sensitisation potential. A 34-year-old woman with a three-year history of recurrent lip and perioral dermatitis frequently used O’Keeffe’s Lip Repair lip balm as a lip care product. Patch testing including to single ingredients in the lip balm showed a positive reaction to the lip balm itself (- at day 2, + at day 3, + at day 7) and positive reaction to TMPD-AA-GC 5% pet at (+ at day 2, ++ at day 3 and + at day 7). The exact sensitiser within this three-component copolymer is unknown. This case underscores the value of patch testing with patient-specific products and individual ingredients to detect rare contact allergens and highlights TMPD-AA-GC as a potential sensitiser in cosmetics.