2,2'-[azobis(1-methylethylidene)]bis[4,5-dihydro-1H-imidazole dihydrochloride

Endpoint summary

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

Number of animals: 6; Exposure time: 24 h; Intact and abraded skin was exposed

GLP compliance:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

The rabbits were individually house in metal cages,
Room temperature: 19 °C
Relative humidity: 30-70 %
Air exchange: 19/h
Aritificial light: 12h in each 24 hour period

Preparation of test site:

other: abraded and intact skin

Vehicle:

water

Controls:

not required

Amount / concentration applied:

0,5 g amount of 2,2’-[azobis(1-methylethylidene)]bis[4,5-dihydro-1H-imidazole dihydrochloride, was applied under a 2.5 cm square gauze pad moist with 0,5mL distiiled water

Duration of treatment / exposure:

24 h

Observation period:

24 and 72 h

Number of animals:

6

Irritation parameter:

erythema score

Remarks:

Intact skin

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

erythema score

Remarks:

Abraded skin

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

edema score

Remarks:

Intact skin

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Irritation parameter:

edema score

Remarks:

Abraded skin

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible

Erythema and Eschar Formation

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

Maximum possible: 4

Oedema Formation No oedema ............................................................................................ 0

Very slight oedema (barely perceptible) ...................................................... ...... . 1

Slight oedema (edges of area well defined by definite raising) .............................. ............ 2

Moderate oedema (raised approximately 1 mm) 3

Severe oedema (raised more than 1 mm and extending beyond area of exposure) ......... ..... 4

Maximum possible: 4

Interpretation of results:

other: Based on "Appraisal of the Safety of Chemicals in Foods, Drugs, and Cosmetics", published by the Association of Food and Drug Officials of the United States, 1959, p. 46.

Conclusions:

2,2’-[azobis(1-methylethylidene)]bis[4,5-dihydro-1H-imidazole dihydrochloride is considered to be non - irritant to rabbit skin

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vitro / ex vivo

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 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying i) Chemicals Inducing Serious Eye Damage and ii) Chemicals Not Requiring Classification for Eye Irritation or Serious Eye Damage)

GLP compliance:

yes (incl. QA statement)

Species:

cattle

Strain:

not specified

Details on test animals or tissues and environmental conditions:

Isolated bovine cornea: The test system (target tissue) is the isolated bovine cornea. Bovine eyes are obtained as a by-product of freshly slaughtered cattle (age of the animals: minimum 12 months, maximum 60 months).

Vehicle:

other: De-ionized water

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

20% (w/v) solution in de-ionized water

Duration of treatment / exposure:

The corneas were incubated in a horizontal position at about 32 °C for approximately 4 hours (non-surfactant solids).

Number of animals or in vitro replicates:

Each treatment group (test substance, NC and PC) consisted of 3 corneas

Irritation parameter:

in vitro irritation score

Value:

2.6

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Interpretation of results:

GHS criteria not met

Remarks:

The IVIS score of the test substance of 2.6 would classify it as a substance that does not cause eye irritation or serious eye damage

Conclusions:

Applying the criteria of the OECD 437 for the assessment of the BCOP test results, the IVIS score of the test substance of 2.6 would classify it as a substance that does not cause eye irritation or serious eye damage. However, the Guideline also states, that due to limited accuracy of the BCOP test to correctly identify substances that do not require classification for eye irritation or serious eye damage, this test method should not be the first choice to initiate a bottom-up approach. Based on this statement test substances leading to IVIS <3 are generally examined in the EpiOcular test as well.

Reference 2

Endpoint:

eye irritation, other

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 405 (Acute Eye Irritation / Corrosion)

Qualifier:

according to guideline

Guideline:

OECD Guideline 492 (Reconstructed Human Cornea-like Epithelium (RhCE) Test Method for Identifying Chemicals Not Requiring Classification and Labelling for Eye Irritation or Serious Eye Damage)

Version / remarks:

adopted 28. July 2015

GLP compliance:

yes (incl. QA statement)

Species:

human

Details on test animals or tissues and environmental conditions:

The EpiOcularTM model (OCL-200) is a three-dimensional non-keratinized tissue construct composed of normal human derived epidermal keratinocytes used to model the human corneal epithelium. The EpiOcularTM tissues (surface 0.6 cm²) arecultured on especially prepared cell culture inserts and are
commercially available as kits (EpiOcular™ 200), containing 24 tissues on shipping agarose.

Vehicle:

other: The test substance is applied undiluted, therefore no preparation of the test substance in a vehicle was performed

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

A volume of 50 μL of the test material was applied covering the whole tissue surface.

Duration of treatment / exposure:

exposure time: 6 hours

Duration of post- treatment incubation (in vitro):

Postincubation period: 18 h

Number of animals or in vitro replicates:

3

Irritation parameter:

other: Optical density (wavelength 570 nm)

Value:

4

Negative controls validity:

valid

Remarks:

100

Positive controls validity:

valid

Remarks:

21

Interpretation of results:

Category 2 (irritating to eyes) based on GHS criteria

Conclusions:

In the current case, the EpiOcular test was positive and the test substance was assessed to be irritating.

Executive summary:

Applying the criteria of the OECD 437 for the assessment of the BCOP test results, the IVIS score of the test substance of 2.6 would classify it as a substance that does not cause eye irritation or serious eye damage. However, the Guideline also states, that due to limited accuracy of the BCOP test to correctly identify substances that do not require classification for eye irritation or serious eye damage, this test method should not be the first choice to initiate a bottom-up approach. Based on this statement and the experience of the test facility, test substances leading to IVIS < 3 are generally examined in the EpiOcular test as well. In the current case, the EpiOcular test was positive and the test substance was assessed to be irritating.

Based on the results for BCOP and EpiOcular Test and applying the evaluation criteria described in section 3.10, Azo Initiator VA044 shows an eye irritation potential in the in vitro eye irritation test strategy under the test conditions chosen.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Skin irritation/corrosion:

2,2’-[azobis(1-methylethylidene)]bis[4,5-dihydro-1H-imidazole dihydrochloride is considered to be non - irritant to rabbit skin

Eye irritation:

In the current case, the EpiOcular test was positive and the test substance was assessed to be eye irritating. Based on the findings the substance is considered to fulfil the criteria for classification of eye irritant category 2.