2,6-dibromo-4-cyanophenyl octanoate

Endpoint summary

Description of key information

Key, M-185084-01-2; Guinea Pig Maximisation Test (guinea pig, OECD 406, GLP): skin sensitizing

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:

22 Jun - 16 Jul 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 2021

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

adopted 1992

Deviations:

no

GLP compliance:

yes

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

Remarks:

Crl: (HA) BR

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River France (Saint-Aubin-les-Elbeuf, France)
- Females nulliparous and non-pregnant: yes
- Age at study initiation: approximately 3 months
- Weight at study initiation: 342 ± 10 g (males), 345 ± 10 g (females)
- Housing: individually in polycarbonate cages equipped with dust-free sawdust (SICSA, Alfortville, France)
- Diet: 106 pelleted diet (UAR, Villemoisson-sur-Orge, France), ad libitum
- Water: filtered drinking water (0.22 µm FG Millipore membrane), ad libitum
- Acclimation period: at least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 23
- Humidity (%): 30 - 70
- Air changes (per hr): approximately 12
- Photoperiod (hrs dark / hrs light): 12 / 12
- IN-LIFE DATES: From: 22 Jun 1999 To: 16 Jul 1999

Route:

intradermal

Vehicle:

corn oil

Concentration / amount:

0.1 mL at a concentration of 5% (w/w)

Day(s)/duration:

single injection on Day 1

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Concentration / amount:

0.5 mL at a concentration of 50% (w/w)

Day(s)/duration:

starting on Day 8 for 48 h

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Concentration / amount:

0.5 mL at a concentration of 50% (w/w)

Day(s)/duration:

starting on Day 22 for 24 h

No. of animals per dose:

10 (control, 5 per sex), 20 (treatment group, 10 per sex)

Details on study design:

RANGE FINDING TESTS
A. INDUCTION EXPOSURE
For intradermal induction: One male and one female guinea pig were each given intradermal injections of the following test item concentrations: 5% with or without FCA. The injection sites were evaluated 24 and 48 h and 6 days after the injections.
For topical induction: Two concentrations (25% and 50%) were tested on two guinea pigs. 0.5 mL of test substance formulation were placed on a dry gauze pad and applied to the skin by means of an occlusive dressing for 24 h. The skin reactions were evaluated 24 and 48 h after removal of the dressing. No skin reactions were recorded for both time points after topical application of the test formulations (25 - 50%).

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) Freund's Complete Adjuvant (FCA)/sterile physicological saline solution
Injection 2: 5% test substance in corn oil
Injection 3: 5% test substance in corn oil in a 1:1 mixture of (v/v) FCA/0.9% NaCl
Epicutaneous: 50% test substance in corn oil
- Control group:
Intradermal (3 pairs of injections):
Injection 1: a 1:1 mixture (v/v) FCA/sterile physicological saline solution
Injection 2: corn oil
Injection 3: corn oil in a 1:1 mixture (v/v) FCA/0.9% NaCl
Epicutaneous: corn oil
- Site: interscapular region (intradermal + epicutaneous)
- Frequency of applications: once (each)
- Duration: intradermal induction was performed on Day 1, topical induction was performed on Day 8-10
- Concentrations: intradermal 5%, epicutaneous 50%

B. CHALLENGE EXPOSURE
- No. of exposures: 1 (challenge)
- Day(s) of challenge: challenge was performed three weeks after intradermal induction on Day 22
- Exposure period: 24 h
- Test groups: test substance and vehicle only
- Control group: test substance and vehicle only
- Site: posterior flanks (right: test substance; left: vehicle)
- Concentrations: 50%
- Evaluation (hr after challenge): 24 and 48 h after removal of dressing

OTHER:
The animals were observed for clinical signs and mortality at least once daily throughout the entire study period. Individual body weights were recorded on the day of allocation into the groups and on Days 1, 8, 15 and 25 of the study.

Challenge controls:

The control group is actually a challenge control.

Positive control substance(s):

yes

Remarks:

The GPMT was checked for reliability in a separate study on female guinea pigs using DNCB as a positive control substance.

Positive control results:

The positive control DNCB at a concentration of 1% (w/w) induced positive skin sensitization reactions in 9/10 (90%) guinea-pigs.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

induction: 5% (intradermal), 50% (epicutaneous); challenge: 50% (epicutaneous)

No. with + reactions:

20

Total no. in group:

20

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

induction: 0% (intradermal), 0% (epicutaneous); challenge: 50% (epicutaneous)

No. with + reactions:

0

Total no. in group:

10

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

induction: 5% (intradermal), 50% (epicutaneous); challenge: 50% (epicutaneous)

No. with + reactions:

20

Total no. in group:

20

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

induction: 0% (intradermal), 0% (epicutaneous); challenge: 50% (epicutaneous)

No. with + reactions:

0

Total no. in group:

10

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

induction: 0.1% (intradermal), 1% (epicutaneous); challenge: 1% (epicutaneous)

No. with + reactions:

9

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

other: control group for positive control

Dose level:

induction: 0% (intradermal), 0% (epicutaneous); challenge: 0% (epicutaneous)

No. with + reactions:

0

Total no. in group:

5

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

induction: 0.1% (intradermal), 1% (epicutaneous); challenge: 1% (epicutaneous)

No. with + reactions:

7

Total no. in group:

10

Remarks on result:

positive indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

other: control group for positive control

Dose level:

induction: 0% (intradermal), 0% (epicutaneous); challenge: 0% (epicutaneous)

No. with + reactions:

0

Total no. in group:

5

An ocular lesion recorded in one animal of the treated group (male no. 36), from Day 23, was not considered to be a consequence of treatment with the test substance. No other clinical signs and no mortality were observed during the study. The body weight gain of the treated animals was similar to that of the control animals. No cutaneous reactions were observed in the animals of the control group. In the treated group, a well-defined or moderate erythema (grade 2 or 3) was noted in all animals at the 24 and 48-hour readings. A very slight or slight oedema (grade 1 or 2) was recorded in 6/20 animals at the 24-hour reading and in 15/20 animals at the 48-hour reading. Dryness of the skin was observed in all animals at the 48-hour reading.

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Conclusions:

The study was conducted according to OECD guideline 406, under GLP and is considered valid and reliable. Under the test conditions, the test substance produced a sensitizing reaction to the skin of guinea pigs.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

To evaluate skin sensitising properties of the test substance, data on a GLP-conform skin sensitisation study according to OECD Guideline 406 is available. Further, supporting evidence was obtained according to EPA Guideline 81-6.

 

In the key study (M185084-01-2), skin sensitising properties of the test substance were evaluated in guinea pigs according to the maximization method of Magnusson and Kligman (OECD 406) in compliance with GLP. Concentrations of 5 and 50% (w/w) were chosen for intradermal and epicutaneous induction, respectively, in regard to the results of a preliminary study. The test group comprised 10 male and 10 female guinea pigs and the control group comprised 5 male and 5 female guinea pigs (strain: Dunkin-Hartley). On Day 1, 3 pairs of intradermal injections were performed in the interscapular region of all animals:

1) Freund's complete adjuvant (FCA) diluted at 50% (v/v) with 0.9% NaCl (both groups),

2) test substance at a concentration of 5% in corn oil (treated group) or vehicle alone (control group),

3) test substance (5%, (w/w)) in corn oil in a 50/50 (v/v) mixture with FCA/0.9% NaCl (treated group) or corn oil in a 50/50 mixture with FCA/0.9% NaCl (control group).

On Day 7, the skin of animals was treated with 0.5 mL sodium lauryl sulfonate (10%, in vaseline), in order to induce local skin irritation. On Day 8, the test substance (treated group) or the vehicle (control group) was applied topically and covered by an occlusive dressing for 48 hours. The challenge with 50% test substance (w/w) was performed on the right flank of all animals on Day 22. The left flank received the vehicle only and served as control. Test substance and vehicle were held in place by an occlusive dressing for 24 hours. No mortality was recorded until the end of the observation period and body weight gain was comparable among the groups. Scoring of skin reactions was performed 24 and 48 h after removal of the dressing (challenge). In the control group, no skin reactions were observed (0/10) and in the treatment group all animals showed skin reactions (erythema) on the treated flank (20/20). Thus under the conditions tested, the test item produced a sensitizing reaction to the skin of guinea pigs. Treatment with DNCB as positive control substance demonstrated that the test system utilized by the laboratory could detect potential contact skin sensitizer.

 

The result of the key study is supported by another skin sensitization study (M-283271-02-1). In this supporting study, the test material was applied to guinea pigs in accordance to the EPA OPP 81-6 guideline. The study was performed under GLP conditions and is considered reliable and valid.

Ten animals received the test substance (5% w/w suspension in mineral oil) and 10 animals received ethylenediamine (0.1% v/v solution in 0.9% saline) as positive control. An intradermal injection of 0.05 ml of the test suspension or solution was made into the clipped upper left scapular area of each animal. An injection of the vehicle alone was made in the right upper scapular area. Intradermal injections of 0.1 ml of the test suspension or solution were then made into the clipped dorsal lumbosacral area of the Guinea pigs every 2-3 days until a total of 9 doses had been administered. Following this course of treatment, the animals were allowed a 14-day 'incubation period' and then a challenge intradermal injection of 0.05 ml of the suspension or dilution was made in the lower left scapular area. A challenge injection of the vehicle alone was made in the lower right scapular area. Dermal responses were recorded 24 and 48 h after the challenge injection.

After the first application of the test item, 1/10 test sites was very faint pink. There was a fairly consistent degree of irritation present following the fifth through tenth 'sensitizing' injections, including large areas of slight to well-defined erythema on nearly all sites at the 24 and 48h readings. Similar irritation resulted from the challenge injection, but it was not as severe at the 48h reading. There were no reactions following the vehicle challenge dose. Ethylenediamine elicited slightly less severe and inconsistent reactions than the test item. Overall, the test item induced skin reactions in 10/10 (24 h after challenge) and 5/10 guinea pigs (48 h after challenge), respectively. The positive control induced skin reactions in 7/10 (24 h after challenge) and 3/10 guinea pigs (48 h after challenge). Based on the results of this study, the test item is regarded to exhibit sensitising properties towards the skin of guinea pigs under the conditions tested.

 

Further, the skin sensitizing potential of the test item was evaluated in an additional study (M-280122-01-1) carried out according to GLP principles (non GLP compliant), and in accordance to FIFRA guidelines and  the Buehler method. Animals were separated into groups of 10 (5 males and 5 females each) animals. One group was treated with the test item at a concentration of 10% (w/w) suspended in 0.25% aqueous methyl cellulose (vehicle), another group was treated with the vehicle and a third group received the positive control substance dinitrochlorobenzene (DNCB) at a concentration of 0.5% (for induction) or 0.1% (for the challenge), respectively. The animals were subjected to 3 epicutaneous (occlusive dressing) induction doses, spaced one week apart, followed by a 2-week rest period. After this period, single challenge doses of 10% test item, 0.25% methyl cellulose solution, or 0.1% DNCB were administered (epicutaneous, occlusive dressing). Induction applications were performed on the left and challenge treatments on the right scapular area of the animals. Skin reactions were then monitored at 24 and 48 h after the challenge application. Administration of the vehicle alone produced no skin reactions on any of the 10 guinea pigs at the 24 and 48 h scoring time point. Application of the positive control DNCB led to a positive response in 10/10 animals at 24 and 48 h after challenge. The test substance produced a positive response in 2/10 of the animals tested. Reactions in the 2 animals were minimal (slight, solid erythema or moderate patchy erythema). Based on those results, the test item was judged to have a slight sensitizing potential under the conditions of the study. No study record is provided in IUC for this study as sufficiently conclusive data are obtained based on the above mentioned studies GLP guideline studies, which revealed a clear response in regard to skin sensitization.

 

References not included in IUC:

Detailed information on references not included in IUC are available in the CSR and in chapter 13.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available data, the test item induced skin sensitization in guinea pigs. Therefore, CLP/EU GHS criteria are met and the substance is classified as Skin sensitising category 1 according to Regulation (EC) No 1272/2008 and Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation, Index No. 608-017-00-0).