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Objectives: To provide an updated estimate of the prevalence of contact allergy in the general population based on data from our previous review combined with new data from an updated search for relevant studies published between 2007 and 2017. Methods: Two authors independently searched PubMed for studies reporting on the prevalence of contact allergy in samples of the general population. Proportion meta-analyses were performed to calculate the pooled prevalence estimates of contact allergy. Results: A total of 28 studies were included in the analysis, covering 20 107 patch tested individuals from the general population. Overall, the pooled prevalence of contact allergy was 20.1% (95% confidence interval [CI]: 16.8%-23.7%). In children and adolescents (<18 years), the prevalence was 16.5% (95%CI: 13.6%-19.7%). The prevalence was significantly higher in women (27.9% [95%CI: 21.7%-34.5%]) than in men (13.2% [95%CI: 9.3%-17.6%]). The most common allergen was nickel (11.4% [95%CI: 9.4%-13.5%]), followed by fragrance mix I (3.5% [95%CI: 2.1%-5.4%]), cobalt (2.7% [95%CI: 2.1%-3.4%]), Myroxylon pereirae (1.8% [95%CI: 1.0%-2.7%]), chromium (1.8% [95%CI: 1.3%-2.6%]), p-phenylenediamine (1.5% [95%CI: 1.0%-2.1%]), methylchloroisothiazolinone/methylisothiazolinone (1.5% [95%CI: 0.8%-2.5%]), and colophonium (1.3% [95%CI: 1.0%-1.6%]).Conclusions: This meta-analysis confirmed that at least 20% of the general population are contact-allergic to common environmental allergens. It highlights the need for more effective preventive strategies for common allergens in consumer goods, cosmetics, and the workplace.contact allergy, epidemiology, general population, hapten, meta-analysis, prevalence and Janssen Pharmaceuticals. J. P. Thyssen is supported by an unrestricted grant from the Lundbeck Foundation. ORCID Farzad Alinaghi

Non-mix fragrances are the most important single fragrance allergens among consecutive patients. The test concentration of the single FM I constituents should be increased when possible.

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 0.3% pet. Methods: A multicentre 3-week double-blind vehicle-controlled repeated open application test (ROAT) study with a simulated fine fragrance containing Lim-OOHs at 1260, 420 and 140 ppm, equal to a dose/area per application of Lim-OOHs of 3.0, 0.99 and 0.33 μg/cm 2 , was performed.Results: Among 11 subjects allergic to Lim-OOHs, 11 (100%), 7 (64%), and 3 (27%), respectively, reacted to the applied doses. No reactions were seen in 17 healthy controls exposed to the highest dose. This difference in reactivity was statistically significant (P < 0.0001). Among 13 subjects with doubtful patch test reactions to Lim-OOHs, two (15%) had positive ROAT reactions to the highest Lim-OOH dose applied (P = 0.36 as compared with controls).Conclusions: Contact allergy to Lim-OOHs is of clinical relevance in patients with positive patch test reactions. A doubtful patch test reaction to Lim-OOHs 0.3% pet. can be of clinical relevance.