(E)-2-methoxy-4-(prop-1-enyl)phenol

Sensitisation data (human)

Administrative data

Endpoint:

sensitisation data (humans)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

No data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Experimental inhalation of fragrance allergens in predisposed subjects: effects on skin and airways.

Author:

Schnuch A, Oppel E, Oppel T, Römmelt H, Kramer M, Riu E, Darsow U, Przybilla B, Nowak D and Jörres RA.

Year:

2010

Bibliographic source:

Br J Dermatol. 162(3):598-606.

Reference 2

Reference Type:

publication

Title:

Fragrance sensitisers: Is inhalation an allergy risk?

Author:

Basketter D and Kimber I.

Year:

2015

Bibliographic source:

Regul Toxicol Pharmacol. 73(3):897-902.

Materials and methods

Type of sensitisation studied:

respiratory

Study type:

study with volunteers

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

A study was conducted to investigate whether patients with contact allergy to isoeugenol would react to inhalation exposure at the level of the airways and skin. Eleven patients sensitized to Isoeugenol were exposed twice for 60 min to 1000 µg/m3 of this compound in an exposure chamber at rest, and to geraniol 1000 µg/m3 as a control. Patients wore protective clothing to prevent skin exposure. There were at least 3 weeks between the two exposures. A history of allergic asthma and ⁄or rhinitis was present in six out of 11 of the patients in the treated group, while four of 11 showed a history of atopic dermatitis. Patch tests were performed and patients were required to show at least a positive (+) patch test reaction to be included in the inhalation study. The effects of the inhaled fragrance was performed using a broad panel of subjective and objective measures including the assessment of lung function and systemic and local inflammatory responses (Spirometry, Methacholine inhalation challenges, fractional concentration of exhaled nitric oxide, skin prick tests, analysis of blood samples and questionnaire to report skin, respiratory or general symptoms. The exposure days comprised measurements immediately before as well as immediately and 2 and 5 h after exposure; two further assessments were performed 24 and 72 h after exposure. The authors considered the sample to be adequate and of sufficient size for detecting whether or not there are individuals who can suffer from airway and ⁄or skin responses after inhalation exposure.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Isoeugenol

EC Number:

202-590-7

EC Name:

Isoeugenol

Cas Number:

97-54-1

IUPAC Name:

2-methoxy-4-prop-1-en-1-ylphenol

Test material form:

not specified

Details on test material:

- Name of test material (as cited in study report): Isoeugenol (ISO)
- Source: Kurt Kitzing GmbH (Wallerstein, Germany)
- Analytical purity:not reported
- Isomers composition: not reported

Method

Type of population:

general

Ethical approval:

confirmed and informed consent free of coercion received

Subjects:

- Number of subjects exposed: 11
- Sex: 7 Females + 4 Males
- Age: 59.8 ± 13.9 years
- Other: patients sensitized to Isoeugenol. A history of allergic asthma and ⁄or rhinitis was present in six out of 11 of the patients in the treated group, while four of 11 showed a history of atopic dermatitis. Patch tests were performed and patients were required to show at least a positive (+) patch test reaction to be included in the inhalation study.

Clinical history:

- Patients were recruited from the Departments of Dermatology, Ludwig-Maximilians-University and the Technical University, Munich.
- Medical history (for respiratory hypersensitivity): None of the subjects had asthma or chronic obstructive pulmonary disease, infections within 2 weeks prior to the study or administration of antiallergic drugs.
- Smoking history: No
- Asthma (past ⁄present): 3/2
- Rhinitis: 6
- Atopic dermatitis: 4
- Bronchial hyper-responsiveness: 2
- Skin prick test to aeroallergens: 2
- Skin prick test to fragrances: 0
- Forced expiratory volume in 1 s (FEV1 (% predicted)): 101.9 ± 16.9

Controls:

Geraniol

Route of administration:

inhalation

Details on study design:

SELECTION OF VOLUNTEERS PRIOR TO INHALATION STUDY
- A history of allergic asthma and ⁄or rhinitis was present in six out of 11 of the patients in the treated group, while four of 11 showed a history of atopic dermatitis.
- Patch tests were performed according to the recommendations of the International Contact Dermatitis Research Group (Fregert, 1981) and the German Contact Dermatitis Research Group (Schnuch et al., 2001). Patch test materials (Hermal ⁄Trolab, Reinbek, Germany) were applied for 48 h and readings were taken until at least 72 h after application. Patch tests were performed and patients were required to show at least a positive (+) patch test reaction to be included in the inhalation study.

TYPE AND DETAILS OF TEST(S) USED
- Eleven patients sensitized to isoeugenol were exposed twice for 60 min to 1000 µg/m3 of test substance in an environmental exposure chamber at rest, and to Geraniol 1000 µg/m3 as a control (volume 25 m3 at environmental conditions of 22 ± 1.5 °C and 50 ± 2% relative humidity). The exposure chamber was supplied with recirculated ambient air filtered by activated charcoal. Patients wore occlusive textiles in order to cover the skin completely and to prevent aerogenic exposure. There were at least 3 weeks between the two exposures.
- Target concentrations were achieved by temperature-controlled evaporation into the inlet air stream at a 30 times per hour air-exchange frequency using charcoal adsorption for the recirculated air to avoid a continuous increase in the concentration of the fragrance. Test item concentrations were checked within the first 30 min and again during the second 30 min. These measurements showed that the mean levels of Geraniol and Isoeugenol in all exposures were 1022 and 994 µg/m3, respectively, with coefficients of variation between exposures being 6.5 and 5.2%. For quantitative measurement, a gas chromatograph (Mini 3; Shimadzu, Neufahrn ⁄Freising, Germany) with a flame- ionization detector was used.
- The study comprised seven visits per individual. The first visit (baseline) involved the assessment of a detailed clinical history, a physical examination and a skin prick test. There were three further visits for each of the two exposures performed in each individual. Assessments were performed prior to exposure, and immediately, 2, 5, 24 and 72 h after exposure. Exposures were performed in a single-blinded fashion and there were at least 3 weeks between exposures.
- The assessments after exposure (Table 7.10.4/1) comprised evaluation of the skin status (including photographs), administration of a short questionnaire covering different symptoms, venous puncture, determination of lung function and exhaled nitric oxide, and methacholine inhalation challenge.
- Skin prick test: Skin prick test of test substance was performed at a dilution of 1:10.
- Lung function measurements: Spirometry (Forced expiratory volume in 1 second = FEV1) was performed according to Pellegrino et al., 2005. Measurements were repeated three times and appropriate values selected as proposed in the guidelines.
- Methacholine inhalation challenges were performed following a protocol implementing the APS sidestream nebulizer (Jaeger, Wurzburg, Germany) according to Praml et al., 2005. Provocative doses (PD) were calculated by log-linear interpolation and expressed as cumulative dose leading to a 20% fall of FEV1 (PD20FEV1) relative to the value measured after inhalation of the diluent.
- The fractional concentration of exhaled nitric oxide (FeNO) was determined by a Sievers NOA 280 chemiluminescence analyser (Sievers, Boulder, CO, U.S.A.) at a flow rate of 50 mL/s. An expiratory resistance was used to achieve a pressure of 12 cmH2O and ensure closure of the velum. The flow rate was held constant by the subjects by observing the pressure signal. Three acceptable measurements were performed and their mean was taken for analysis.
- Other:
Blood samples were used for the determination of routine differential cell counts, C-reactive protein (CRP), total serum IgE, pooled specific IgE panel and basal serum tryptase levels.
The level of FeNO and blood eosinophils can be considered as markers of, not necessarily allergic, inflammation.
Subjects reported symptoms related to skin and airways in a self-administered written questionnaire at the start of the exposures and after 30 and 60 min.

Results and discussion

Results of examinations:

- Physical examination: At baseline there was residual eczema in 2/11 patients of the test substance group. Prior to the exposures, neither direct examination nor examination of photographs showed changes in these or the other patients. However, 24 and 72 h after test substance exposure the two patients with pre-existing residual eczema exhibited an eczematous flare, despite the tight-closing protective wear. Except for these changes there were no other clinically detectable changes in the state of the skin or the respiratory system.
- Symptoms: Test substance treated group did not show significant changes after test substance or Geraniol exposure (Friedman’s ANOVA). In particular, no difficulties in breathing or chest tightness were reported. However, 2/11 single patients reported skin symptoms 24 and 72 h after exposure, while one of them had already reported such symptoms at baseline.
- Baseline values of Spirometry (FEV1) prior to the exposures were comparable and lung function did not significantly change over time after the exposures. There were also no significant differences between corresponding exposures.
- When comparing the four different time points after test substance exposure, exhaled nitric oxide (FeNO) showed a significant difference (P = 0.046, ANOVA). Specifically, FeNO decreased 5 h after exposure and remained unchanged over the next 2 days and baseline values were significantly different from those measured after 72 h (P < 0.05, Newman–Keuls).
- At baseline 2/11 patients in the test substance group showed a PD20FEV1 (cumulative dose leading to a 20% fall of FEV1) of methacholine indicative of bronchial hyper-responsiveness (BHR). PD20FEV1 did not show statistically significant changes when evaluated after each of the different exposure conditions, although there was a tendency for a decrease especially in the test substance group. There was no relationship between the changes in methacholine responsiveness and the patients’ histories of asthma and ⁄or rhinitis.
- Laboratory assessment: Erythrocyte, leucocyte and thrombocyte counts as well as CRP levels were in the normal range prior to the exposures. Similarly, eosinophils were within the normal range (< 7%). Total IgE was increased (> 100 kU/L) in 1/11 patient of the test substance group. Mast cell tryptase concentration was elevated (> 11.4 µg/L) in 1/11 patient of the test substance group (> 20 µg/L) prior to the exposures. When comparing post exposure values with baseline values, the leucocyte number showed a significant increase irrespective of the type of exposure (P < 0.05 each). Correspondingly, while the absolute number of eosinophils did not significantly change after the exposures, their percentages decreased. Neither the levels of CRP nor those of mast cell tryptase showed statistically significant changes after the exposures.
- Relationships between skin response measures: The 2/11 patients in the test substance group who showed a flare after exposure also reported an increase in skin symptom scores after 24 and 72 h.
- Re-exposure of the two patients responding with haematogenic contact eczema: The 2/11 patients who demonstrated an objective positive skin response, were re-exposed to a concentration of test substance 10 µg/m3 several weeks later. According to environmental measurements, this concentration is attainable under worst-case conditions (room of volume 27 m3; windows and doors closed for > 24 h) by evaporation from commercially available ‘plug-ins’ containing 0.2% isoeugenol. No symptoms of the skin or other symptoms were induced.

Any other information on results incl. tables

There were no significant changes in lung function but a tendency towards an increased bronchial hyper-responsiveness after exposure to any of the compounds. Laboratory parameters of inflammation did not indicate responses. Single patients reported respiratory symptoms unrelated to objective measures. In contrast, the observed skin symptoms corresponded to the patients’ specific sensitization. Four patients reported symptoms compatible with delayed-type hypersensitivity, and two demonstrated a flare after exposure to isoeugenol. On re-exposure they did not respond to a lower, more realistic level of isoeugenol.

Inhalation of high concentrations of fragrance contact allergens apparently poses a risk for some patients of developing manifest haematogenic contact dermatitis, while the changes in the respiratory tract are limited to symptoms in some subjects without objective changes.

According to the authors, based on a weight of evidence, isoeugenol and other fragrance materials found in air fresheners do not represent a risk of respiratory allergy.

Applicant's summary and conclusion

Conclusions:

Under the test conditions, no significant changes in lung function were observed suggesting the absence of respiratory sensitization.

Executive summary:

Eleven patients sensitized to Isoeugenol were exposed twice for 60 min to 1000 µg/m3 of this compound in an exposure chamber at rest, and to geraniol 1000 µg/m3 as a control. Patients wore protective clothing to prevent skin exposure. There were at least 3 weeks between the two exposures. A history of allergic asthma and ⁄or rhinitis was present in six out of 11 of the patients in the treated group, while four of 11 showed a history of atopic dermatitis. Patch tests were performed and patients were required to show at least a positive (+) patch test reaction to be included in the inhalation study. The effects of the inhaled fragrance was performed using a broad panel of subjective and objective measures including the assessment of lung function and systemic and local inflammatory responses (Spirometry, Methacholine inhalation challenges, fractional concentration of exhaled nitric oxide, skin prick tests, analysis of blood samples and questionnaire to report skin, respiratory or general symptoms. The exposure days comprised measurements immediately before as well as immediately and 2 and 5 h after exposure; two further assessments were performed 24 and 72 h after exposure. The authors considered the sample to be adequate and of sufficient size for detecting whether or not there are individuals who can suffer from airway and ⁄or skin responses after inhalation exposure.

There were no significant changes in lung function but a tendency towards an increased bronchial hyper-responsiveness after exposure to any of the compounds. Laboratory parameters of inflammation did not indicate responses. Single patients reported respiratory symptoms unrelated to objective measures. In contrast, the observed skin symptoms corresponded to the patients’ specific sensitization. Four patients reported symptoms compatible with delayed-type hypersensitivity, and two demonstrated a flare after exposure to isoeugenol. On re-exposure they did not respond to a lower, more realistic level of isoeugenol.

Inhalation of high concentrations of fragrance contact allergens apparently poses a risk for some patients of developing manifest haematogenic contact dermatitis, while the changes in the respiratory tract are limited to symptoms in some subjects without objective changes. According to the authors, based on a weight of evidence, available studies suggest that isoeugenol lack the potential to cause allergic sensitisation of the respiratory tract. Isoeugenol provides an illustrative example of a chemical allergen that can be experienced either through inhalation exposure, or by skin contact, but which fails to provoke the quality of immune response necessary for sensitisation of the respiratory tract. It is for this reason that, although isoeugenol causes skin sensitisation, and is a well established human contact allergen, it is not associated with respiratory allergy.