Quantification of l-carvone in toothpastes available on the Swedish market

Abstract

Background: Toothpastes have widespread use in the population, and contain flavours to give a pleasant and often minty aroma. Flavours are prevalent allergens in toothpastes, and adverse reactions often present as perioral dermatitis or stomatitis. l-Carvone, a mint flavour found in spearmint oil, is one of these allergens. There are few studies on contact allergy to l-carvone, and some of them have indicated a positive relationship with oral lichenoid lesions.

Objectives: To qualitatively and quantitatively investigate the presence of l-carvone in commercially available toothpastes on the Swedish market.

Methods: l-Carvone in 66 toothpastes was analysed with straight-phase high-performance liquid chromatography. The product labels were studied with regard to limonene.

Results: l-Carvone was found in 64 of 66 toothpastes (concentration: 0.00005-0.35%). In 10 of these, the concentration exceeded 0.1%. Higher concentrations of l-carvone were found if limonene was listed on the label.

Conclusion: The majority of toothpastes on the Swedish market contain l-carvone, but the concentration hardly relates to the advertised flavour or labelled ingredients. It is hitherto unknown whether the found concentrations are sufficient for induction of contact allergy in individuals with healthy oral mucosa or in those with oral lichenoid lesions or other mucosal disease.

Keywords: contact allergy; contact dermatitis; flavour; fragrances; high-performance liquid chromatography; l-carvone; limonene; oral lichen planus; oral lichenoid lesions; spearmint; toothpastes.