4-[[2-methoxy-4-[(4-nitrophenyl)azo]phenyl]azo]phenol

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Remarks:

guinea pig maximization test (GPMT)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From August 10, 1999 to September 10, 1999

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

A GPMT study was submitted as this was already available before the requirement for LLNA testing was published.

Species:

guinea pig

Strain:

other: Pirbright-White

Sex:

female

Details on test animals and environmental conditions:

From Harlan Winkelmann
Bodyweight (mean): 362g
Groups of 5 animals
Temperature: 20 +/- 3°C and Relative humidity: 50 +/- 20%
Lighting time: 12 hours daily
Food and water: ssniff Ms-H (V2233) and tap water (ad libitum)

Route:

intradermal

Vehicle:

other: sesame oil

Concentration / amount:

5% (with and without Freund's Complete Adjuvant)

Adequacy of induction:

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

Route:

epicutaneous, occlusive

Vehicle:

other: sesame oil

Concentration / amount:

25% in 0.5 mL

Day(s)/duration:

48h

Adequacy of induction:

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

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

other: sesame oil

Concentration / amount:

25% in 0.5 mL

Day(s)/duration:

24h

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

RANGE FINDING TEST
Determination of the primary non-irritant concentration 3
Determination of the tolerance of the intradermal injections 2
MAIN STUDY
Control group 5
Test substance group 10

Details on study design:

RANGE FINDING TESTS:
Determination of the primary non-irritant concentration
Determination of the tolerance of the intradermal injections


MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2*0.1 mL 5% intradermal + 0.5 mL 25% epidermal
- Exposure period: dermal: 48 h
- Test groups: 1
- Control group: 1
- Site: intradermal: dorsal neck
- Frequency of applications: 1 intradermal, 1 dermal
- Duration: 21 days
- Concentrations: intradermal: 5%; dermal: 25%

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 22 of the study
- Exposure period: 24 h
- Test groups: 1
- Control group: 1
- Site: flanks
- Concentrations: 25%
- Evaluation (hr after challenge): 24 and 48 h after removal of patches (= 48 and 72 h after start of challenge)

Challenge controls:

left flank

Positive control substance(s):

yes

Remarks:

alpha-hexyl cinnamic aldehyde (50% in PEG 400).

Positive control results:

80% of the treated animals exhibited a positive skin reaction during the observation period.

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

25%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

25%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

25%

No. with + reactions:

0

Total no. in group:

5

Remarks on result:

no indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

25%

No. with + reactions:

0

Total no. in group:

5

Remarks on result:

no indication of skin sensitisation

Criterion for evaluation: the number of sensitized test animals (treshold of 30%).

Preliminary test results:

- Determination of the primary non-irritant concentration: no signs of irritation. The challenge was thus realized with the test substance at a concentration of 25% in sesame oil.

- Determination of the tolerance of the intradermal injections: the 5% preparation caused well defined erythema and edema, the 1.0% solution induced a slight irrition, and no effects were observed for the 0.2% test substance prepration. Based on those results, the 5% preparation was selected.

Main test results:

- The intradermal injections with Freund's Adjuvant (with or without test substance) caused severe erythema and edema as well as indurations, encrustations, and necrosis.When the test substance was administered with sesame oil, slight up to well defined erythema and oedema were observed. The vehicle alone did not cause any sign of irritation.

- After removal of the patches, severe erythema and edema, indurated and encrusted skin as well as necrosis were observed at the sites peviously treated with Freund's Adjuvant. The daministration sites treated with the test substance or the vehicle alone, showed no signs of irritation.

- For the dermal challenge treatment, no skin reactions were observed in the control and treatment groups, 24 and 48h after removal of the occlusive bandage.

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of a Guinea pig maximisation study, the test substance was not sensitizing.

Executive summary:

A study was conducted to determine the skin sensitisation potential of the test substance (in the form of a brown powder of 38.8% purity) according to OECD Guideline 406 and EU Method B.6 (guinea pig maximization test (GPMT)). Female Pirbright-White guinea pigs (5 controls and 10/test group) were first exposed to the substance indradermally (injections of 50% Freund’s Adjuvant, 5% test substance in sesame oil, or 5% test substance in 50% Freund’s Adjuvant) and dermally (25.0% test substance in sesame oil) for 48 h. The dermal challenge consisted in the application of an occlusive bandage for 24 h with 25.0% test substance in sesame oil. Examinations were conducted 24 and 48 h after removal of the patches. The positive control used was alpha-hexyl cinnamic aldehyde and the vehicle (sesame oil) or the Freund’s Adjuvant served as negative control. The body weight gains of the animals were not impaired and the treated animals showed no signs of intoxication throughout the study. The positive control induced irritation in 80% of the animals and no skin reactions were observed in the negative control groups. None of the ten animals of the treatment group showed a positive skin response after the challende procedure. Under the study conditions, the test substance was considered to be not sensitizing to guinea pig (Seeberger, 1999).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

A study was conducted to determine the skin sensitisation potential of the test substance (in the form of a brown powder of 38.8% purity) according to OECD Guideline 406 and EU Method B.6 (guinea pig maximization test (GPMT)). Female Pirbright-White guinea pigs (5 controls and 10/test group) were first exposed to the substance indradermally (injections of 50% Freund’s Adjuvant, 5% test substance in sesame oil, or 5% test substance in 50% Freund’s Adjuvant) and dermally (25.0% test substance in sesame oil) for 48 h. The dermal challenge consisted in the application of an occlusive bandage for 24 h with 25.0% test substance in sesame oil. Examinations were conducted 24 and 48 h after removal of the patches. The positive control used was alpha-hexyl cinnamic aldehyde and the vehicle (sesame oil) or the Freund’s Adjuvant served as negative control. The body weight gains of the animals were not impaired and the treated animals showed no signs of intoxication throughout the study. The positive control induced irritation in 80% of the animals and no skin reactions were observed in the negative control groups. None of the ten animals of the treatment group showed a positive skin response after the challende procedure. Under the study conditions, the test substance was considered to be not sensitizing to guinea pig (Seeberger, 1999).

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of an in vivo guinea pig maximisation test, no classification for skin sensitization is required for the test substance according to CLP (EC 1272/2008) criteria.