Peppermint, ext.

Endpoint summary

Description of key information

Skin irritation:
- in vivo (rabbit): slightly/moderately irritating
Eye irritation:
- WoE: not irritating

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12/04/1983 - 05/06/1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study not performed according to a guideline or GLP, but results are acceptable as basic data.

Qualifier:

no guideline followed

Principles of method if other than guideline:

A study was conducted to investigate the irritation effects of Peppermint Flavour – Brazilian when applied once to intact skin under a semi-occlusive dressing. A 4-hour semi-occlusive patch test was conducted on 8 New Zealand white rabbits, 9 - 12 weeks old. The dorsal region was clipped 3-4 days before the beginning of the study. A 0.5 ml aliquot of the undiluted test material and appropriate control standards were applied to gauze pads attached to strips of adhesive tape. The patches were placed on the clipped dorsum of animals, and the animals were then immobilized in body sleeves for 4 hours. After removal of the patches, the sites were wiped clean of the excess test material. Reactions were graded at 4, 24, 48 and 72 hours after patch removal. The sites are scored for erythema, oedema, cracking and scaling and any other feature using an 8-point anchored ordinate scale ranging from "a" (very slight) to "h" (severe). At the end of the test the irritation reaction produced by each test material at 2 and 72 hours after treatment is assigned an overall irritation score. In addition, the overall irritation scores for all treatment sites/group and the total irritation score/group were recorded.

GLP compliance:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 9 - 12 weeks

ENVIRONMENTAL CONDITIONS: no data

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

yes

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 ml
- Concentration (if solution): 100 % (undiluted)

CONTROLS:
- Diethyl Phthalate and Geraniol were used as standards for comparison.

Duration of treatment / exposure:

4 hours

Observation period:

0, 24, 48, and 72 hours after treatment, and occasionally up to 7 days after treatment.

Number of animals:

8 (1 rabbit killed at 24 hours due to broken back)

Details on study design:

TEST SITE
- Area of exposure: the dorsal region
- Type of wrap if used: Patches were prepared by attaching flexible polythene (3cm x 3cm) to zinc oxide plaster (9cm x 2.5cm). Cotton guaze (2.5cm2) was laid on the polythene. 0.5 ml of test solution was applied to the dry patch. Animals were immobilised in a canvas body sleeve for 4 hours after application of the patch.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): After removal of the patches, the sites were wiped clean of the excess test material.
- Time after start of exposure: 4 hours

SCORING SYSTEM:
a (marginal/very slight)
b (slight)
c (fairly distinct)
d (quite distinct)
e (becoming well developed)
f (well developed)
g (becoming severe)
h (severe)

Overall irritation scores were assigned based on the following grading scale:
0 – Normal skin
1 – Marginal (grade a)
2 – Slight (grades up to bbbb at 24 and 72h)
3 – Slight/moderate (grades ca-cc at 24h and reduced to slight at 72h)
4 – Moderate (grades c and d at 24h, at least slight/moderate at 72h)
5 – Strong (as moderate but evidence of ¼ of site affected by necrosis)
6 – Severe (most of site affected by necrosis)
7 – Extreme (deep necrosis over whole site)

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 24 hours

Score:

1.6

Max. score:

4

Reversibility:

not fully reversible within: 72 hours

Remarks on result:

other: Mean scores were derived after conversion

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 48 hours

Score:

1.6

Max. score:

4

Reversibility:

not fully reversible within: 72 hours

Remarks on result:

other: Mean scores were derived after conversion

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 72 hours

Score:

1.8

Max. score:

4

Reversibility:

no data

Remarks:

after 72 hours

Remarks on result:

other: Mean scores were derived after conversion

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 24 hours

Score:

1.6

Max. score:

4

Reversibility:

not fully reversible within: 72 hours

Remarks on result:

other: Mean scores were derived after conversion

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 48 hours

Score:

1.6

Max. score:

4

Reversibility:

not fully reversible within: 72 hours

Remarks on result:

other: Mean scores were derived after conversion

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 72 hours

Score:

1.8

Max. score:

4

Reversibility:

no data

Remarks:

after 72 hours

Remarks on result:

other: Mean scores were derived after conversion

Irritant / corrosive response data:

Peppermint Flavour - Brazilian showed mainly slight/moderate effects with one site showing pale brown tissue 24 and 72 hours after treatment. This response is similar to the control Geraniol.

Other effects:

Not applicable

Result expressed as overall irritation score for each animal as reported in the study:

Animal number	265	272	288	291*	311	313	317	322	Total irritation score per group
Group
Diethyl Phtalate	1	1	1	-	1	1	1	0	6
Geraniol	3	3	3	-	2	4	4	3	22
Peppermint Flavour - Brazilian	3	3	4	-	2	4	3	5	24

* rabbit 291 killed at 24h due to broken back

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Peppermint Flavour - Brazilian showed mainly slight/moderate effects with one site showing pale brown tissue 24 and 72 hours after treatment. This response is similar to the control Geraniol. However Geraniol showed no evidence of necrosis. In order to classify the test substance in accordance with EU classification, the irritation scoring from "a" to "h", as reported in the study, is converted to the grading of skin reactions as defined by OECD Guideline 404. The mean scores calculated from the numerical values given to the skin irritation observed at the 24, 48, and 72 hour examinations were 1.6, 1.6, and 1.8 resp., for erythema and also for oedema. Based on these conversed scores and according to EU criteria Peppermint Flavour - Brazilian was considered not irritating and the test substance does not have to be classified according to the classification criteria outlined in 67/548/EEC and 1272/2008.

Executive summary:

A study was conducted to investigate the irritation effects of Peppermint Flavour - Brazilian when applied once to intact skin under a semi-occlusive dressing. A 4-hour semi-occlusive patch test was conducted on 8 New Zealand white rabbits. The test material and 2 control substances (Diethyl Phthalate and Geraniol), were applied undiluted to the clipped dorsum of the 8 rabbits. Reaction grades for erythema, oedema, cracking and scaling were assessed 4, 24, 48, and 72 hours after treatment by using grades ranging from "a"(very slight) to "h"(severe). An overall irritation score was assigned to each tested substance ranging from 0 (normal skin) to 7 (extreme). Peppermint Flavour - Brazilian showed mainly slight/moderate effects with one site showing pale brown tissue 24 and 72 hours after treatment. This response is similar to the control Geraniol. However Geraniol showed no evidence of necrosis. In order to classify the test substance in accordance with EU classification, the irritation scoring from "a" to "h" as reported in this study, is converted to the grading of skin reactions as defined by OECD Guideline 404. The mean scores calculated from the numerical values given to the skin irritation observed at the 24, 48, and 72 hour examinations were 1.6, 1.6, and 1.8 resp. for erythema, and also for oedema. Based on these conversed scores and according to EU criteria Peppermint Flavour - Brazilian was considered not irritating and the test substance does not have to be classified according to the classification criteria outlined in 67/548/EEC and 1272/2008.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Two dermal irritation studies performed with peppermint oil are available. In the key study, peppermint oil was applied once to intact skin under a semi-occlusive dressing on 8 white rabbits. Reaction grades for erythema, oedema, cracking and scaling were assessed 4, 24, 48, and 72 hours after treatment by using grades ranging from "a"(very slight) to "h"(severe). An overall irritation score was assigned to each tested substance ranging from 0 (normal skin) to 7 (extreme). Peppermint oil showed mainly slight/moderate effects.

After conversion of the used irritation scores to the grading of skin reactions as defined by OECD Guideline for the testing of chemicals No. 404: Acute Dermal Irritation/Corrosion, it could be concluded that cornmint oil does not have to be classified as irritating in accordance with 67/548/EEC or 1272/2008/EC.

In a supporting study, skin irritation was assessed as part of a dermal toxicity test in which 10 rabbits (New Zealand White) were exposed to peppermint oil on the clipped abraded abdominal skin for 24 –hour. Signs of dermal irritation were considered slight to moderate (unknown scoring method). Based on these results and according to EU criteria the test material could be considered not irritating.

As both studies were not performed according to current guidelines with an irregular scoring system, and the major constituent L-menthol is classified as irritating to the skin and present at levels higher than the thresholds mentioned for classification and labeling (in both 68/548/EEC and 1272/2008/EC), the essential oils belonging to the mint category are considered to be irritating to the skin.

 

The conclusion on eye irritation was based on a Weight of Evidence approach. An in vivo eye irritation test with peppermint oil was available. In this test, peppermint oil was applied to the eyes (conjunctival sac) of eight rabbits per dose group following the method of Draize. Afterwards, the eyes of 4 animals were rinsed for 1 minute with physiological saline and those of the remaining 4 were not rinsed. At 10, 20, 30, 40, 50, or 60% no effects and no reactions were observed. Under the conditions of this study, 10 to 60% Brazilian menthol (peppermint oil) in olive oil was not an eye irritant in rabbits. The documentation is a summary of methods and results, individual scores are not included. Therefore, definite conclusions on classification in accordance with 67/548/EEC and 1272/2008/EC cannot be drawn.

Additionally, an in vitro BCOP test in accordance with OECD437 was performed with category member cornmint oil. Results show a mean in vitro irritancy score (IVIS) of 4.3 indicating that the substance is not severe irritant or corrosive (A substance that induces an IVIS ≥ 55.1 is defined as a corrosive or severe irritant).

Based on these results and according to EU criteria the test material could be considered not irritating. However, the major constituent L-menthol is classified for Eye Irritation Category 2 according to CLP (Regulation 1272/2008/EC). As this constituent is present at levels higher than the thresholds mentioned for classification and labelling in that Regulation, the essential oils belonging to the mint category can be considered to be irritating to the eye and should also be classified with Eye Irritation Category 2.

According to the Dangerous Substances Directive (67/548/EEC), L-menthol is not classified as an eye irritant and therefore classification of the essential oils belonging to the mint category as eye irritant is also not required.

Justification for selection of skin irritation / corrosion endpoint:
The selected study is the key study for this endpoint.

Justification for selection of eye irritation endpoint:
No selection is made as a Weight of Evidence approach was followed which is described below.

Effects on skin irritation/corrosion: slightly irritating

Justification for classification or non-classification

Based on the available information and the classification of the major constituent L-menthol, the substance peppermint oil needs to be classified for skin irritation in accordance with the Dangerous Substances Directive (67/548/EEC) and the CLP Regulation (1272/2008/EC).

Based on the available information and the classification of the major constituent L-menthol, the substance peppermint oil needs to be classified as eye irritant in accordance with the CLP Regulation (1272/2008/EC), but not in accordance with the Dangerous Substances Directive (67/548/EEC).