Cyclohexanemethanol, 4-(1-methylethyl)-

Endpoint summary

Description of key information

Results of a GLP in vivo sensitisation study on the substance performed according to OECD 429 test guidelines have demonstrated that the compound is a sensitizer.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 15, 2012 to May 14, 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Deviation from OECD guideline 429: Animals were individually housed. However, this is standard policy at the testing facility to rule out possibility of cross-contamination.

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

yes

Remarks:

Animals were individually housed.

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories UK Ltd., Oxon, UK
- Age at study initiation: 8 to 12 weeks
- Weight at study initiation: 15 to 23 g
- Housing: individual, solid-floor polypropylene cages furnished with softwood woodflakes
- Diet (e.g. ad libitum): ad libitum, 2014C Teklad Global Rodent diet
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25
- Humidity (%): 30-70
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12

IN-LIFE DATES: From: April 11, 2012 To: April 24, 2012

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

0, 25, 50, or 100%

No. of animals per dose:

5

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: Not reported
- Irritation: scored daily
- Lymph node proliferation response: ear thickness scored daily on Days 1 to 6

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response: at least one concentration of the test item results in a threefold or greater increase in 3HTdR incorporation compared to control values.

TREATMENT PREPARATION AND ADMINISTRATION:
prepared using acetone/olive oil as vehicle and applied within 2 hours of preparation to the dorsal surface of the ear. The volume was 25 µL applied to the dorsal surface of each ear (% coverage not reported).
There was no subsequent covering of the application site.

ADDITIONAL INFORMATION: SCORING SYSTEM:
For skin irritation, a mean ear thickness increase of equal to or greater than 25% was considered to indicate excessive irritation (measured using an Oditest micrometer at pre-dose and post-dose on Day 1, post-dose on Days 2 and 3, and on Days 4, 5, and 6).
Scale for Erythema/Overall Irritation
Observation Score
No erythema 0
Very slight erythema (barely perceptible) 1
Well-defined erythema 2
Moderate to severe erythema 3
Severe erythema (beef redness) to eschar formation preventing grading of erythema 4

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

ANOVA

Positive control results:

Stimulation Index for positive control was 5.76. α-Hexylcinnamaldehyde, tech., 85% was considered to be a sensitizer under the conditions of the test.

Key result

Parameter:

EC3

Value:

44

Key result

Parameter:

SI

Value:

1.88

Test group / Remarks:

25 % v/v

Key result

Parameter:

SI

Value:

3.39

Test group / Remarks:

50 % v/v

Key result

Parameter:

SI

Value:

7.25

Test group / Remarks:

100 % v/v

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA
Mean DPM - vehicle = 1943.83 (±437.24)
Mean DPM - 25 % v/v = 3657.87* (±734.59)
Mean DPM - 50 % v/v = 6593.81* (±2088.69)
Mean DPM - 100 % v/v = 14121.54** (±3172.65)

DETAILS ON STIMULATION INDEX CALCULATION
Mean DPM vehicle / mean DPM test group

EC3 CALCULATION
EC3 = c + [[(3-d)/(b-d)] x (a-c)]
a = lowest concentration giving stimulation index >3 <=> 50 % v/v
b = actual stimulation index caused by ‘a’ <=> 3.39
c = highest concentration failing to produce a stimulation index of 3 <=> 25 % v/v
d = actual stimulation index caused by ‘c’ <=> 1.88

CLINICAL OBSERVATIONS:
There were no deaths. No signs of systemic toxicity were noted in the test or control animals during the test. Very slight erythema (barely perceptible) was noted on both ears of the animals treated with the undiluted test item on Days 1, 2, and 3 and also on both ears of the animals treated with the test item at a concentration of 50% v/v in acetone/olive oil 4:1 on Days 2 and 3. There was no evidence of excessive skin irritation (based on ear thickness measurements) due to the test item at any dose concentration evaluated.

BODY WEIGHTS
Bodyweight changes of the test animals between Day 1 and Day 6 were comparable to those observed in the corresponding control group animals over the same period.

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Conclusions:

Based on the results of the LLNA assay, the substance is considered to be a sensitizer.

Executive summary:

Results from the murine local lymph node assay (LLNA) show a positive response to the substance, with the stimulation index (SI) indicating a positive result (i.e., SI value of >3) at the two highest concentrations tested (i.e., 1.88 at a 25% concentration, 3.39 at a 50% concentration and 7.26 at 100% concentration). The EC3 value was 44% v/v. Consequently, the test item was considered to be a sensitizer according to EU labelling regulations Commission Directive 2001/59/EC. The test item was also classified as a contact sensitizer (Category 1B) according to Regulation (EC) No 1272/2008, relating to the Classification, Labelling and Packaging of Dangerous Substances.

Based on the EC3 value of 44%, the substance could be categorized as a weak sensitizer (Loveless et al., 2010).

There was no evidence of skin irritation due to the test item at any dose concentration evaluated. Only very slight erythema (barely perceptible) that was reversible appeared on the ears of animals treated with the undiluted test item or the test item at a concentration of 50% v/v in acetone/olive oil 4:1, and ear thickness measurements did not indicate an irritation response.

Reference:

Loveless SE, Api A-M, Crevel RWR, Debruyne E, Gamer A, Jowsey IR, et al. Potency values from the local lymph node assay: Application to classification, labelling and risk assessment. Regul Toxicol Pharmacol. 2010;56:24-66.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The potential for the substance to cause skin sensitisation was assessed in an in vivo Local Lymph Node Assay (Harlan Laboratories Ltd., 2012), which was performed according to OECD Guideline for the Testing of Chemicals No. 429 (Skin Sensitisation: Local Lymph Node Assay) and in compliance with GLP.

The test substance was applied to the ears of CBA mice (5/group) at concentrations of 0 (control), 25, 50, or 100% daily for 3 days, and an observation period of an additional 3 days followed. A significant dose-related increase in disintegrations per minute was observed in the 25, 50, and 100% dose groups compared to control and the simulation indices were positive in the 50% and 100% dose groups. The EC3 value was calculated to be 44% v/v. Based on the EC3 value being 44%, the substance could be categorized as a weak sensitizer (Loveless et al., 2010).

The test item was considered to be a sensitizer according to EU labelling regulations Commission Directive 2001/59/EC. The substance was also classified as a contact sensitizer (Category 1B) according to Regulation (EC) No 1272/2008, relating to the Classification, Labelling and Packaging of Dangerous Substances.

Reference

Loveless SE, Api A-M, Crevel RWR, Debruyne E, Gamer A, Jowsey IR, et al. Potency values from the local lymph node assay: Application to classification, labelling and risk assessment. Regul Toxicol Pharmacol. 2010;56:24 -66.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Respiratory Sensitization: Assessment of respiratory sensitization can be done using human data (ECHA 2014 guidance R.7a, Section R7.3.5.2) that may indicate respiratory reactions (e.g., from consumer experience or occupational exposure). In the absence of such data for the substance, the respiratory sensitisation potential was assessed using the integrated evaluation strategy indicated by ECHA in the 2014 guidance (see Figure 7.3-2, page 245). As the substance is a weak sensitizer, its structural relation to other chemicals that cause respiratory sensitization was addressed. The substance has no structural alerts such as those presented in Table 7.3-1 (ECHA 2014 guidance, page 236) or provided in the document http://ec.europa.eu/health/scientific_committees/docs/annex6_respiratory.pdf (e.g., iso-thiocyanates, amines, anhydrides, acrylates, diazonium salts, and reactive dyes, metals). Therefore, it is concluded that the substance is not considered as a respiratory sensitizer.

Justification for classification or non-classification

Based on the results of the LLNA, the stimulation index was ≥ 3 and EC3 > 2%. As a result, the substance meets the criteria for Category 1B skin sensitization classification according to Regulation (EC) No 1272/2008, Annex I section 3.4.

Based on the absence of structural alerts indicating a respiratory sensitisation potential, the substance does not meet the classification as a respiratory sensitizer according to Regulation (EC) No 1272/2008, Annex I section 3.4.