Hexanamide, N-(2-hydroxyethyl)-3,5,5-trimethyl-

Endpoint summary

Description of key information

Based on the results of the LLNA, the test substance is not considered to be sensitising to skin.

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2010

Deviations:

no

GLP compliance:

yes

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: Charles River UK, Margate
- Age at study initiation: 8 to 11 weeks
- Weight at study initiation: 18.4 to 22.5 g
- Housing: Two per cage
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 8 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 to 21°C
- Humidity (%): 48% to 65%
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: To: 01 August to 13 August 2012

Vehicle:

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

Concentration:

0%, 25%, 50% and 100%

No. of animals per dose:

4

Details on study design:

RANGE FINDING TESTS:
- Compound solubility: Pre-study formulation trial
- Irritation: No irritation in preliminary phase animals
- Lymph node proliferation response: Maximum SI = 2.2

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay
- Criteria used to consider a positive response: SI greater than or equal to 3 in any group

TREATMENT PREPARATION AND ADMINISTRATION: Once daily for 3 consecutive days: 25 microlitres per ear per mouse of control or test formulation

Statistics:

Dixon's Q-test for detection of a single outlier applied to the individual disintegrations per minute values

Key result

Parameter:

SI

Value:

ca. 1

Test group / Remarks:

control

Remarks on result:

other: Mean DPM at 0% = 1646

Key result

Parameter:

SI

Value:

ca. 1.9

Test group / Remarks:

dose 25%

Remarks on result:

other: Mean DPM at 25% = 3062

Key result

Parameter:

SI

Value:

ca. 2.2

Test group / Remarks:

dose 50%

Remarks on result:

other: Mean DPM at 50% = 3573

Key result

Parameter:

SI

Value:

ca. 2.2

Test group / Remarks:

dose 100%

Remarks on result:

other: Mean DPM at 100% = 3640

Interpretation of results:

other: CLP criteria not met

Conclusions:

Under the conditions of the study, since treatment with the substance at concentrations of up to 100% (ie undiluted substance) did not achieve a stimulation index of greater than or equal to 3, it was considered that the test item does not have the potential to cause skin sensitisation.

Executive summary:

A study was conducted to determine the sensitising potential of test substance in a mouse local lymph node assay conducted according to OECD Guideline 429, in compliance with GLP. The objective of this study was to determine the delayed contact hypersensitivity potential of the test substance. The study was performed using female CBA/Ca mice. A pre‑study formulation trial showed that acetone:olive oil, 4:1 v/v (AOO) was the most suitable vehicle for the substance and that a concentration of 50% was achievable. In the preliminary test an open application of 25 µL of undiluted test substance was administered onto the dorsum of each ear of 2 animals. As a result of the findings from the preliminary test, four animals per dose were exposed to the test substance at 25, 50 and 100% concentrations in the main study. The animals received 25 µL of the appropriate formulation onto the dorsum of each ear on 3 consecutive days. There were no systemic signs and no signs of local irritation in any animal during the observation period. Clinical signs were restricted to wetness to the head in animals treated with the substance. This was considered to be merely an accumulation of test substance residues. Body weight losses were recorded in all groups, including controls, and were not considered to be treatment-related. Three days after the final application each animal received an intravenous injection of [methyl-3H] thymidine into the lateral tail vein. Approximately 5 h later the draining lymph nodes were collected in order that incorporation of tritiated thymidine could be assessed by scintillation counting. The stimulation indices (SI) for the three test groups, when compared with the vehicle, were 1.9, 2.2 and 2.2, respectively. Under the conditions of the study, since treatment with the substance at concentrations of up to 100% (i.e., undiluted substance) did not achieve a stimulation index of greater than or equal to 3, it was considered that the test substance does not have the potential to cause skin sensitisation (Robertson, 2012).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

A study was conducted to determine the sensitising potential of test substance in a mouse local lymph node assay conducted according to OECD Guideline 429, in compliance with GLP. The objective of this study was to determine the delayed contact hypersensitivity potential of the test substance. The study was performed using female CBA/Ca mice. A pre‑study formulation trial showed that acetone:olive oil, 4:1 v/v (AOO) was the most suitable vehicle for the substance and that a concentration of 50% was achievable. In the preliminary test an open application of 25 µL of undiluted test substance was administered onto the dorsum of each ear of 2 animals. As a result of the findings from the preliminary test, four animals per dose were exposed to the test substance at 25, 50 and 100% concentrations in the main study. The animals received 25 µL of the appropriate formulation onto the dorsum of each ear on 3 consecutive days. There were no systemic signs and no signs of local irritation in any animal during the observation period. Clinical signs were restricted to wetness to the head in animals treated with the substance. This was considered to be merely an accumulation of test substance residues. Body weight losses were recorded in all groups, including controls, and were not considered to be treatment-related. Three days after the final application each animal received an intravenous injection of [methyl-3H] thymidine into the lateral tail vein. Approximately 5 h later the draining lymph nodes were collected in order that incorporation of tritiated thymidine could be assessed by scintillation counting. The stimulation indices (SI) for the three test groups, when compared with the vehicle, were 1.9, 2.2 and 2.2, respectively. Under the conditions of the study, since treatment with the substance at concentrations of up to 100% (i.e., undiluted substance) did not achieve a stimulation index of greater than or equal to 3, it was considered that the test substance does not have the potential to cause skin sensitisation (Robertson, 2012).

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of the LLNA study, the test substance does not warrant a classification for skin sensitisation according to EU CLP (EC 1272/2008) criteria.