Limonene and linalool hydroperoxides review: Pros and cons for routine patch testing.

Limonene and linalool are among the most common fragrance terpenes used in everyday products. They are pre-haptens, forming hydroperoxides (Lim-OOHs, Lin-OOHs) upon oxidation and inducing frequent positive patch test reactions in patients with dermatitis, and yet they are not routinely tested in Europe. This review evaluates current patch testing with Lim-OOHs and Lin-OOHs by asking whether hydroperoxide patch testing is warranted, examining the difficulties or challenges related to reading and interpreting hydroperoxide patch test results with currently available material, and assessing their relevance.

Contact allergy to haptens in the Swedish baseline series: Results from the Swedish Patch Test Register (2010 to 2017).

Background: Allergic contact dermatitis has considerable public health impact and causative haptens vary over time.

Objectives: To report the prevalence of contact allergy to allergens in the Swedish baseline series 2010 to 2017, as registered in the Swedish Patch Test Register.

Methods: Results and demographic information for patients tested with the Swedish baseline series in 2010 to 2017 were analysed.

Patch testing with purified and oxidized citronellol.

Background: Citronellol is a commonly used fragrance terpene included in fragrance mix II. As with many other fragrance terpenes, citronellol is susceptible to autoxidation. Citronellol hydroperoxides are formed in large amounts and are the only oxidation products identified as sensitizers in oxidized citronellol.

Can patch testing with methylchloroisothiazolinone/methylisothiazolinone be optimized using a new diagnostic mix? - A multicenter study from the Swedish Contact Dermatitis Research Group.

Background: Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) and methylisothiazolinone (MI) are tested to detect contact allergy to these isothiazolinones.

Objectives: To study if an aqueous patch test preparation with MCI and MI in a mix of 0.015% and 0.

Contact allergy to citral and its constituents geranial and neral, coupled with reactions to the prehapten and prohapten geraniol.

Background: Citral is commonly used as a fragrance and flavor material and consists of the aldehydes geranial and neral. Citral is included in fragrance mix (FM) II. Geranial and neral have also been identified in autoxidation of geraniol, a fragrance compound present in FM I.

Allergic contact dermatitis caused by hydroperoxides of limonene and dose-response relationship-A repeated open application test (ROAT) study.

Background: Contact allergy to oxidized limonene, with hydroperoxides of limonene (Lim-OOHs) as the main allergens, is common. However, high proportions of weak positive and doubtful patch test reactions have been reported.

Objectives: To determine the clinical relevance, elicitation threshold and dose-response relationship of Lim-OOHs in individuals with a positive or doubtful patch test reaction to standard Lim-OOHs 0.

Contact allergy to oxidized geraniol among Swedish dermatitis patients-A multicentre study by the Swedish Contact Dermatitis Research Group.

Background: Geraniol is a widely used fragrance terpene, and is included in fragrance mix I. Geraniol is prone to autoxidation, forming the skin sensitizers geranial, neral, and geraniol-7-hydroperoxide. Oxidized geraniol has previously been patch tested in 1 clinic, giving 1% to 4.

Oxidized limonene and oxidized linalool - concomitant contact allergy to common fragrance terpenes.

Background: Limonene and linalool are common fragrance terpenes. Both oxidized R-limonene and oxidized linalool have recently been patch tested in an international setting, showing contact allergy in 5.2% and 6.

Patch Testing with Main Sensitizers Does Not Detect All Cases of Contact Allergy to Oxidized Lavender Oil.

Lavender oil is an essential oil obtained from lavender (Lavendula angustifolia). The main components linalool and linalyl acetate have been shown to autoxidize in contact with oxygen in the air, forming sensitizing hydroperoxides. Patients with suspected allergic contact dermatitis were consecutively patch-tested with oxidized lavender oil 6% pet.

Air-oxidized linalyl acetate - an emerging fragrance allergen?

Background: Linalyl acetate is a fragrance chemical that is prone to autoxidation. Exposure to linalyl acetate occurs through cosmetic products and essential oils, but is difficult to assess, as linalyl acetate is not labelled in the EU.

Objective: To investigate the frequencies of contact allergy to oxidized linalyl acetate among dermatitis patients, and to investigate the autoxidation of linalyl acetate in terms of hydroperoxide formation and sensitization potency.

Swedish Experiences From Patch Testing Methylisothiazolinone Separately.

The preservative methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) is a well-known sensitiser and present in the Swedish baseline series since the 1980s. The proportions of MCI/MI are 3:1. MI alone has been used as a preservative since less than 10 years.

Cross-reactivity between citral and geraniol - can it be attributed to oxidized geraniol?

Background: The fragrance compound geraniol is susceptible to autoxidation when in contact with air, and to cutaneous metabolism. In both processes, the isomeric aldehydes geranial and neral are formed. Citral consists of geranial and neral.

Patch testing with a textile dye mix in two concentrations - a multicentre study by the Swedish contact dermatitis research group.

Unlabelled: Disperse dyes, which are used for colouring synthetic textile fibres, are well-known contact sensitisers. To investigate the outcome of patch-testing with a textile dye mix (TDM) at 7 dermatology clinics in Sweden, a TDM tested at 2 concentrations was included into the baseline series during one year. The mix consisted of Disperse (D) Blue 35, D Yellow 3, D Orange 1 and 3, D Red 1 and 17, all 1.

Positive patch test reactions to oxidized limonene: exposure and relevance.

Background: R-Limonene is a common fragrance terpene found in domestic and industrial products. R-Limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. In a recent multicentre study, 5.

Limonene hydroperoxide analogues show specific patch test reactions.

Background: The fragrance terpene R-limonene is a very weak sensitizer, but forms allergenic oxidation products upon contact with air. The primary oxidation products of oxidized limonene, the hydroperoxides, have an important impact on the sensitizing potency of the oxidation mixture. One analogue, limonene-1-hydroperoxide, was experimentally shown to be a significantly more potent sensitizer than limonene-2-hydroperoxide in the local lymph node assay with non-pooled lymph nodes.

Air-oxidized linalool elicits eczema in allergic patients - a repeated open application test study.

Background: Linalool is a commonly used fragrance terpene that forms potent sensitizers upon oxidation. In a recent multicentre study, we found that 7% of 2900 patients showed positive patch test reactions to oxidized linalool at 6.0%.

Patch testing with formaldehyde 2.0% in parallel with 1.0% by the Swedish contact dermatitis research group.

In a multicentre study consecutively patch-tested dermatitis patients were tested simultaneously with 1.0% and 2.0% (w/v) formaldehyde in aqua applied with a micropipette (15 µl) to the filter paper disc in Finn Chambers (0.

An international multicentre study on the allergenic activity of air-oxidized R-limonene.

Background: Limonene is a common fragrance terpene that, in its pure form, is not allergenic or is a very weak allergen. However, limonene autoxidizes on air exposure, and the oxidation products can cause contact allergy. Oxidized R-limonene has previously been patch tested in multicentre studies, giving 2-3% positive patch test reactions in consecutive patients.

Air-oxidized linalool: a frequent cause of fragrance contact allergy.

Background: Linalool is a common fragrance terpene that, in pure form, is not allergenic or is a very weak allergen. However, linalool autoxidizes on air exposure, and the oxidation products can cause contact allergy. In a Swedish study, oxidized linalool 6.

Contact allergy to air-exposed geraniol: clinical observations and report of 14 cases.

Background: The fragrance terpene geraniol forms sensitizing compounds via autoxidation and skin metabolism. Geranial and neral, the two isomers of citral, are the major haptens formed in both of these activation pathways.

Objectives: To investigate whether testing with oxidized geraniol detects more cases of contact allergy than testing with pure geraniol.

Linalool--a significant contact sensitizer after air exposure.

Background: Linalool is a widely used fragrance terpene. Pure linalool is not allergenic or a very weak allergen, but autoxidizes on air exposure and the oxidation products can cause contact allergy. Oxidized (ox.

Air oxidation increases skin irritation from fragrance terpenes.

Background: Linalool and limonene are common fragrance terpenes that autoxidize on air exposure. The pure compounds are not allergenic but their oxidation products can cause contact allergy. Little has been investigated regarding the irritancy of oxidized terpenes.

Limonene hydroperoxide analogues differ in allergenic activity.

Background: The fragrance terpene R-limonene is a very weak sensitizer but forms allergenic oxidation products upon contact with air. Oxidized (ox.) limonene is a frequent cause of contact allergy in clinical testing.