Fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol

Endpoint summary

Description of key information

In vivo (GPMT): not sensitising

Human data (RIPT): not sensitising

Read-across from structural analogue source substance 2,2-bis[[(1-oxoisooctadecyl)oxy]methyl]-1,3-propanediyl bis(isooctadecanoate) (CAS 62125-22-8)

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 Nov - 23 Dec 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted Jul 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government if the United Kingdom

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

A non-LLNA test is available that was performed prior to the current data requirements, stipulated in Regulation (EC) No 1907/2006. In accordance with the same Regulation, the data was included to avoid unnecessary testing.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: David Hall Limited, Staffordshire, UK
- Age at study initiation: 8 -12 weeks
- Weight at study initiation: 332 - 383 g (range)
- Housing: The animals were housed singly or in pairs in solid-floor polyporpylene cages furnished with woodflakes.
- Diet: Guinea Pig FD1 Diet (Special Diets Services Limited, Essex, UK), ad libitum
- Water: Tap water, ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17 - 23
- Humidity (%): 30 - 70
- Air changes (per hr): Approximately 15
- Photoperiod (hrs dark / hrs light): 12/12

- IN-LIFE DATES: From: 15 Nov 1999 To: 23 Dec 1999

Route:

intradermal

Vehicle:

arachis oil

Concentration / amount:

1% (w/w)

Day(s)/duration:

Single injection on Day 1

Adequacy of induction:

highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically

Route:

epicutaneous, occlusive

Vehicle:

arachis oil

Concentration / amount:

25% (w/w)

Day(s)/duration:

Applied on Day 7, 48 h

Adequacy of induction:

highest concentration used causing mild-to-moderate skin irritation and well-tolerated systemically

No.:

#1

Route:

epicutaneous, open

Vehicle:

arachis oil

Concentration / amount:

10 and 25% (w/w)

Day(s)/duration:

Applied on Day 21, 24 h

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

10 (test groups), 5 (controls)

Details on study design:

RANGE FINDING TESTS: To determine a suitable concentration for the intradermal induction in the main study, 2 concentrations of the test substance (1 and 5% w/w) in arachis oil BP were selected. A total of 2 female guinea pigs each received 4 injections of 0.1 mL of one concentration only. The degree of erythema at the injection sites was recorded approximately 24, 48 and 72 h, and 7 days after injection. Clinical signs of systemic toxicity were also recorded. A concentration of 5% w/w in arachis oil BP induced erythema (grade 1) after seven days, therefore a concentration of 1% w/w was selected for the intradermal induction stage of the main study. To determine a suitable concentration for the epicutaneous induction in the main study, 2 females were intradermal injected with Freund's Complete Adjuvant on Day 0, and then each treated by epicutaneous application with 5, 10, 25 and 50% w/w of the test substance in arachis oil BP. The test substance was applied to the clipped flanks of the animals under occlusive dressings for 48 hours, and the degree of erythema and oedema was assessed approximately 1, 24 and 48 h after patch removal. A concentration of 50% w/w in arachis oil BP induced erythema (grade 2) and edema (grade 1) after 48 h, therefore a concentration of 25% w/w was selected for the epicutaneous induction stage of the main study.
To determine a suitable concentration for the epicutaneous challenge in the main study, 2 females were treated by epicutaneous application with 5, 10, 25 and 50% w/w of the test substance in arachis oil BP. The test substance was applied to the clipped flanks of the animals under occlusive dressings for 48 hours, and the degree of erythema and oedema was assessed approximately 1, 24 and 48 h after patch removal. The concentrations of the test material selected for the main study topical challenge were 25 and 10% w/w in arachis oil BP.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2 (intradermal and epicutaneous, respectively)
- Exposure period: single injection (intradermal) and 48 h (epicutaneous)
- Test groups:
Intradermal (3 pairs of injections):
Injection 1: a 1:1 mixture v/v FCA/water
Injection 2: a 1% w/w formulation of the test substance in arachis oil BP
Injection 3: a 1% w/w formulation of the test material in a 1:1 mixture v/v FCA/water
Epicutaneous: 25% w/w of the test substance in arachis oil BP
- Control group:
Intradermal (3 pairs of injections):
Injection 1: a 1:1 mixture v/v FCA/water
Injection 2: arachis oil BP
Injection 3: a 50% w/w formulation of arachis oil BP in a 1:1 mixture v/v FCA/water
Epicutaneous: blank patch
- Site: shoulder region (intradermal and epicutaneous)
- Frequency of applications: Day 0 (intradermal) and Day 7 (epicutaneous)
- Duration: Days 0 - 7
- Concentrations: intradermal 1% w/w, epicutaneous 25% w/w

B. CHALLENGE EXPOSURE
- No. of exposures: 1 (challenge)
- Day(s) of challenge: 21
- Exposure period: 24 h
- Test groups: test substance in arachis oil BP
- Site: right flank (25% w/w), left flank (10% w/w)
- Concentrations: 10 and 25% w/w
- Evaluation (hr after challenge): 25 and 48 h after patch removal

OTHER: Approximately 24 and 48 h after intradermal injection the degree of erythema at the injection sites was evaluated. The degree of erythema and oedema was assessed approximately 1 and 24 h after patch removal following the topical induction. Any evidence of systemic toxicity was recorded. The bodyweight of each animal was recorded at the start and end of the study.

Positive control substance(s):

yes

Positive control results:

Reliability checks were performed at least every 6 months at the testing laboratory to assess the sensitivity and reliability of the test method. A summary of the studies performed from Dec 1996 to Jul 1999 under same experimental conditions was included in the study report. The animals were administered 2-mercaptobenzothiazole. A response of 70-100% of the animals was observed in all the reliability checks. Therefore the positive control is considered to be valid.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

Induction: 1% (intradermal), 25% (epicutaneous); challenge: 10 and 25%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No local skin irritation reactions and no signs of systemic toxicity were observed

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

Induction: 1% (intradermal), 25% (epicutaneous); challenge: 10 and 25%

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

No local skin irritation reactions and no signs of systemic toxicity were observed

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

Induction: arachis oil (intradermal), arachis oil (epicutaneous); challenge: 10 and 25%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No local skin irritation reactions and no signs of systemic toxicity were observed

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

Induction: arachis oil (intradermal), arachis oil (epicutaneous); challenge: 10 and 25%

No. with + reactions:

0

Total no. in group:

5

Clinical observations:

No local skin irritation reactions and no signs of systemic toxicity were observed

Key result

Group:

positive control

Remarks on result:

positive indication of skin sensitisation

Following the intradermal induction, discrete or patchy erythema (grade 1) or moderate to confluent erythema (grade 2) were observed at the injection sites of 10/10 treatment animals (1% test material in arachis oil) and discrete or patchy erythema (grade 1) were noted in 4/5 control animals (arachis oil), both at the 24-hour reading time point. At the 48-hour reading time point, in 10/10 treatment animals discrete or patchy erythema (grade 1), moderate to confluent erythema (grade 2) or intense erythema and swelling (grade 3) and in 4/5 control animal discrete or patchy erythema (grade 1) were observed, respectively. Following the topical induction (25% in arachis oil BP), discrete or patchy erythema (grade 1) or moderate to confluent erythema (grade 2) were observed at the application site in 10/10 treatment animals at the one-hour reading time point and at the 24-hour reading time point. Bleeding from the intradermal induction site was noted in 9/10 treatment animals at the one-hour reading time point following the topical induction, while hardened dark brown/black coloured scabs were noted at the topical induction sites in 1/10 treatment animals at the 24-hour observation time point. 3/5 control animals at the one-hour reading time point and 2/5 animals at the 24-hour reading time point showed discrete or patchy erythema (grade 1) or moderate to confluent erythema (grade 2) following the topical induction, moreover, bleeding from the intradermal induction site was noted in 2/5 control animals at the one-hour reading time point, while hardened dark brown/black coloured scabs were noted at the topical induction sites in 1/5 control animals at the 24-hour observation time point.

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

CLP: not classified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

Data on skin sensitisation of the target substance fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol are available. Moreover, human data on skin sensitisation conducted with the source substance 2,2-bis[[(1-oxoisooctadecyl)oxy]methyl]-1,3-propanediyl (CAS 62125-22-8) were also taken into account for the hazard evaluation.

A guinea pig maximisation test was performed with fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol according to OECD 406 and under GLP conditions (Safepharm Laboratories, 2000). A range-finding study was performed to establish suitable dose levels for the induction and challenge treatments. In the main study, 10 female Dunkin-Hartley guinea pigs were induced intradermally on Day 0 with 3 pairs of injections: with a 1:1 mixture Freund’s Complete Adjuvant (FCA)/water, with 1% test substance in arachis oil BP and with 1% test substance in a 1:1 mixture FCA/water. On day 7, 25% test substance in arachis oil BP in a 1:1 mixture FCA/water was applied to the skin of the animals for 48 hours. On Day 21, the challenge treatment was performed by topical application of 10 and 25% test substance dilution for 24 hours. Five animals served as negative controls and were exposed to the vehicle only. Reliability checks were performed with 2-mercaptobenzothiazole under the same experimental conditions and indicated the reliability and sensitivity of the study. Following the intradermal induction, discrete or patchy erythema (grade 1) or moderate to confluent erythema (grade 2) were observed at the injection sites of 10/10 treatment animals (1% test material in arachis oil) and discrete or patchy erythema (grade 1) were noted in 4/5 control animals (arachis oil), both at the 24-hour reading time point. At the 48-hour reading time point, in 10/10 treatment animals discrete or patchy erythema (grade 1), moderate to confluent erythema (grade 2) or intense erythema and swelling (grade 3) and in 4/5 control animal discrete or patchy erythema (grade 1) were observed, respectively. Following the topical induction (25% in arachis oil BP), discrete or patchy erythema (grade 1) or moderate to confluent erythema (grade 2) were observed at the application site in 10/10 treatment animals at the one-hour reading time point and at the 24-hour reading time point. Bleeding from the intradermal induction site was noted in 9/10 treatment animals at the one-hour reading time point following the topical induction, while hardened dark brown/black coloured scabs were noted at the topical induction sites in 1/10 treatment animals at the 24-hour observation time point. 3/5 control animals at the one-hour reading time point and 2/5 animals at the 24-hour reading time point showed discrete or patchy erythema (grade 1) or moderate to confluent erythema (grade 2) following the topical induction, moreover, bleeding from the intradermal induction site was noted in 2/5 control animals at the one-hour reading time point, while hardened dark brown/black coloured scabs were noted at the topical induction sites in 1/5 control animals at the 24-hour observation time point.

0/10 treatment animals and 0/5 control animals showed skin reactions 24 and 48 h after the challenge treatment, indicating that the test substance did not cause skin sensitisation. Under the conditions of this test the test substance is considered to be not sensitising to guinea pigs.

CAS 62125-22-8

A repeated insult human patch test (RIPT) was conducted to assess the sensitizing potential of 2,2-bis[[(1-oxoisooctadecyl)oxy]methyl]-1,3-propanediyl (CAS 62125-22-8) in 55 human volunteers from the general population (CPTC, 1985). Induction was carried out by 10 repeated semiocclusive applications of the unchanged test substance. Patches were placed on the back of volunteers for 24 hours, followed by a 24 hour rest period (48 hours on weekends). The 10 induction patches were applied to the same site. The induction phase was followed by a resting period of 14 days. Challenge patches were applied to the same site on the back and to a naïve site. Skin reactions were assessed 24 and 48 hours after patch removal. None of the human volunteers showed any skin reactions at the end of the study period. Thus, the test material is not considered sensitising to humans.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The available data on in vivo skin sensitisation with the target substance fatty acids C18-C22 (even numbered), tetraesters with pentaerythritol and the available data on skin sensitisation in humans with the source substance 2,2-bis[[(1-oxoisooctadecyl)oxy]methyl]-1,3-propanediyl (CAS 62125-22-8) do not meet the classification criteria according to Regulation (EC) No 1272/2008, and are therefore conclusive but not sufficient for classification.