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.) linalool has previously been patch tested at a concentration of 2.0% in petrolatum (pet.) in 1511 patients, and 1.3% positive patch test reactions were observed.


OBJECTIVE
To investigate the optimal patch test concentration for detection of contact allergy to ox. linalool.


METHODS
Four concentrations of ox. linalool (2.0%, 4.0%, 6.0%, 11.0% pet.) were tested in 3418 consecutive dermatitis patients.


RESULTS
Ox. linalool 2.0%, 4.0%, 6.0%, and 11.0% pet. detected positive patch test reactions in 0.83%, 3.2%, 5.3%, and 7.2% of the tested patients, respectively. The doubtful reactions increased with rising concentrations but relatively less, giving 5.1%, 6.4%, and 7.3% doubtful reactions, respectively, for ox. linalool 4.0%, 6.0%, and 11.0% pet. Few irritative reactions were seen.


CONCLUSIONS
Raising the patch test concentration for ox. linalool gave a better detection of contact allergy, as many as 5-7% positive patch test reactions were detected. We suggest a patch test concentration of ox. linalool 6.0% pet. for future patch testing, giving a dose per unit area of 2.4 mg/cm(2) when 20 mg test substance is tested in small Finn Chambers.
Department of Dermatology, Sahlgrenska University Hospital, Gothenburg, Sweden. johanna.brared-christensson@vgregion.se
Johanna Bråred
JB
Christensson
Mihály
M
Matura
Birgitta
B
Gruvberger
Magnus
M
Bruze
Ann-Therese
AT
Karlberg
D000080462:Acyclic Monoterpenes; D000388:Air; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006241:Haptens / Q000009:adverse effects / Q000737:chemistry*; D006801:Humans; D008297:Male; D039821:Monoterpenes / Q000009:adverse effects / Q000737:chemistry*; D010084:Oxidation-Reduction; D010328:Patch Tests; D010476:Perfume / Q000009:adverse effects; D010577:Petrolatum / Q000737:chemistry; D013548:Sweden / Q000453:epidemiology
D000080462:Acyclic Monoterpenes; D006241:Haptens; D039821:Monoterpenes; D010476:Perfume; D010577:Petrolatum; C018584:linalool