High prevalence but no current clinical relevance of methyldibromo glutaronitrile since its ban in Turkey in 2015.

BACKGROUND: Regulatory actions significantly reduced methyldibromo glutaronitrile (MDBGN)-induced allergic contact dermatitis (ACD) from cosmetics in Europe. Turkey banned MDBGN in 2015.

OBJECTIVES: To assess sensitization and ACD rates to MDBGN before and after its ban in Turkey.

METHODS: Data from 2653 consecutively patch tested patients between 1996 and 2023 with MDBGN 0.1% pet. (n = 573) or 0.2%-0.3% pet. (n = 1310) or 0.5% pet. (n = 770) were analysed. MDBGN was tested as MDBGN/phenoxyethanol (PE) in 1434 patients.

RESULTS: The sensitization prevalence was 1.7% (45/2653), peaking at 5.3% in 2018 and 2023 with MDBGN 0.3% pet. There was a two-fold male predominance, with patients exclusively ≥20 years old. None of the patients reacted to PE. ACD occurred in 0.7% (19/2653), mainly affecting hands and linked to non-occupational exposure (78.9%), particularly from rinse-off/leave-on cosmetics. The pattern of 'middle-aged men with hand eczema and fragrance allergy' was particularly notable. Occupational ACD was rare (21.1%), occurring mainly in hairdressers from hair gel. Positive reactions with current clinical relevance dropped from 48.3% (1996-2014) to zero after 2015 (p < 0.001).

CONCLUSIONS: The ban effectively reduced MDBGN-induced ACD in Turkey, yet the prevalence of positive patch test reactions remains high, likely due to past exposures or other undisclosed sources. We suggest continued testing of MDBGN in the EBS in Turkey.