2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine)

Endpoint summary

Description of key information

The substance is corrosive to the skin and leads to severe damage of the eyes of rabbits.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin corrosion: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

28 January 2011 - 18 February 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 435 (In Vitro Membrane Barrier Test Method for Skin Corrosion)

Version / remarks:

July 19, 2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test system:

artificial membrane barrier model

Remarks:

test system consisting of a reconstituted collagen matrix

Vehicle:

unchanged (no vehicle)

Details on test system:

SOURCE AND COMPOSITION OF MEMBRANE BARRIER USED
- Was the Corrositex® test kit used: Yes
- Components: InVitro International, Irvine CA, USA, containing: reagents required for qualification and categorization screen, biobarrier matrix powder and diluent, membrane discs and vials containing the Chemical Detection System
- Biobarrier preparation:
The vial containing the biobarrier matrix powder was placed in a water bath at 64 – 68ºC. The entire contents of the biobarrier diluent vial was added slowly to the matrix powder. The stir bar rotated slowly enough to avoid foaming of the solution. 200 μL of the solubilized matrix was pipetted into each of the membrane discs. The membrane discs were then refrigerated for at least 2 hours at 2 – 8ºC. The biobarriers were wrapped and stored at 2 – 8ºC for a maximum of 7 days. Any remaining matrix solution was stored at 2 – 8ºC for up to 30 days in order to prepare additional biobarrier membrane discs.

WAS THE COMPATIBILITY TEST PERFORMED: Yes
For the qualification screen, 150 μL of the test substance was added to the CDS screening tube. If the test substance failed to produce a color change in the CDS within one minute, the test substance could not be analyzed in this system, and no further testing was required.

WAS THE TIMESCALE CATEGORY TEST PERFORMED: Yes
A timescale category test was carried out to distinguish between weak and strong acids or bases.

TEMPERATURE USED DURING TREATMENT: room temperature

METHOD OF DETECTION
- Chemical or electrochemical detection system: The assay is based on the time that is required for the test substance to penetrate through the Corrositex® Biobarrier Membrane and produce a change in the Chemical Detection System (CDS).

METHOD OF APPLICATION: pipette

NUMBER OF REPLICATES: 4 (for test item), 1 (controls)

NUMBER OF INDEPENDENT EXPERIMENTS TO DERIVE FINAL PREDICTION: 1

PREDICTION MODEL / DECISION CRITERIA
Please refer to table 1.

Acceptance criteria:
The Corrositex® assay was accepted if the breakthrough time for the positive control substance was in the historic control range (mean ± 2-3 x standard deviations). To demonstrate the functional integrity of the membrane barrier, the acceptance criterium for the negative control was not to induce membrance breakthrough within a 60 min observation period.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount(s) applied: 500 µL

NEGATIVE CONTROL
- Amount(s) applied: 500 µL

Irritation / corrosion parameter:

penetration time (in minutes)

Run / experiment:

1

Value:

6.41

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Table 2: Results of the membrane Barrier Test.

Test article	Break through time [min:s]
	Vial 1	Vial 2	Vial 3	Vial 4	Mean
00/0695-2	6:43	6:27	6:50	6:44	6:41
Controls
Positive control: sodium hydroxide	13:19	-	-	-	-
Negative control: 10%citric acid	No breakthrough	-	-	-	-

 

Interpretation of results:

Category 1B (corrosive) based on GHS criteria

Reference 2

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2 August 1978 - 14 Dezember 1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Principles of method if other than guideline:

BASF-Test

GLP compliance:

no

Species:

rabbit

Strain:

Vienna White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 2.87 - 3.26 kg

Type of coverage:

occlusive

Preparation of test site:

not specified

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated skin of the same animals served as control

Duration of treatment / exposure:

3 minutes and 1 hour

Observation period:

8 days

Number of animals:

3 min: 4
1 h: 2

Irritation parameter:

erythema score

Basis:

mean

Remarks:

3 min exposure

Time point:

24/48 h

Score:

2.7

Max. score:

4

Reversibility:

not reversible

Remarks on result:

other: 72 h reading is missing

Irritation parameter:

erythema score

Basis:

mean

Remarks:

1 h exposure

Time point:

24/48 h

Score:

4

Max. score:

4

Reversibility:

not reversible

Remarks on result:

other: 72 h reading is missing

Irritation parameter:

edema score

Basis:

mean

Remarks:

3 min exposure

Time point:

24/48 h

Score:

2.1

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Remarks on result:

other: 72 h reading is missing

Irritation parameter:

edema score

Basis:

mean

Remarks:

1 h exposure

Time point:

24/48 h

Score:

3.5

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Remarks on result:

other: 72 h reading is missing

Irritation parameter:

erythema score

Basis:

animal #1

Remarks:

3 min exposure

Time point:

24 h

Score:

2

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

erythema score

Basis:

animal #2

Remarks:

3 min exposure

Time point:

24 h

Score:

2

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

erythema score

Basis:

animal #3

Remarks:

3 min exposure

Time point:

24 h

Score:

4

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

erythema score

Basis:

animal #4

Remarks:

3 min exposure

Time point:

24 h

Score:

3

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

erythema score

Basis:

animal #1

Remarks:

3 min exposure

Time point:

48 h

Score:

2

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

erythema score

Basis:

animal #2

Remarks:

3 min exposure

Time point:

48 h

Score:

2

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

erythema score

Basis:

animal #3

Remarks:

3 min exposure

Time point:

48 h

Score:

4

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

erythema score

Basis:

animal #4

Remarks:

3 min exposure

Time point:

48 h

Score:

2

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

edema score

Basis:

animal #1

Remarks:

3 min exposure

Time point:

24 h

Score:

2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #2

Remarks:

3 min exposure

Time point:

24 h

Score:

2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #3

Remarks:

3 min exposure

Time point:

24 h

Score:

2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #4

Remarks:

3 min exposure

Time point:

24 h

Score:

3

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #1

Remarks:

3 min exposure

Time point:

48 h

Score:

2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #2

Remarks:

3 min exposure

Time point:

48 h

Score:

2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #3

Remarks:

3 min exposure

Time point:

48 h

Score:

2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #4

Remarks:

3 min exposure

Time point:

48 h

Score:

2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

edema score

Basis:

animal #1

Time point:

72 h

Remarks on result:

not measured/tested

Irritation parameter:

erythema score

Basis:

animal #1

Time point:

72 h

Remarks on result:

not measured/tested

Irritant / corrosive response data:

After exposure for 3 minutes, necrotic changes (irreversible full thickness necrosis) were observed in 3/4 rabbits at the reading at 8 days after application.

Mean erythema scores:

Exposure time	3 min	1 h	24 h	48 h	8 days
3 min	0/0/1/1	-	2/2/4/3	2/2/4/2	1/4/4/4
1 h	-	2/2	4/4	4/4	4/4

Mean edema scores:

Exposure time	3 min	1 h	24 h	48 h	8 days
3 min	0/0/0/0	-	2/2/2/3	2/2/2/2	0/0/2/0
1 h	-	2/2	4/3	4/3	2/2

The original BASF grading was converted into the numerical grading according the OECD Draize system.

After exposure for 3 minutes, necrotic changes (irreversible full thickness necrosis) were observed in 3/4 rabbits at the reading at 8 days after application.

Interpretation of results:

Category 1B (corrosive) based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 August 1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Principles of method if other than guideline:

BASF-Test

GLP compliance:

no

Species:

rabbit

Strain:

Vienna White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 2.79 - 3.5 kg

Vehicle:

unchanged (no vehicle)

Controls:

other: the left eye was left untreated and served as a control.

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied: 0.1 mL
- Concentration: undiluted

Duration of treatment / exposure:

24 h, eyes were not washed out

Observation period (in vivo):

8 days

Number of animals or in vitro replicates:

3

Details on study design:

SCORING SYSTEM: according to Draize

Irritation parameter:

overall irritation score

Basis:

mean

Time point:

24/48/72 h

Score:

55.8

Max. score:

110

Reversibility:

not reversible

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

3.2

Max. score:

4

Reversibility:

not reversible

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0.75

Max. score:

2

Reversibility:

not fully reversible within: 72 h

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

2

Max. score:

3

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

3.6

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritant / corrosive response data:

The application of the test substance caused severe damage of ophthalmic tissue including corneal opacity. Due to severe edema, eyeball was not assessable at all readings. After 8 days, the study was terminated since reversibility of the findings was not expected.

Table 1: Eye irritation scores:

	24 h	48 h	72 h	8 days
Cornea	4/3/3	*/3/*	*/3/*	*/*/*
Iris	*/1/0	*/1/*	*/1/*	*/*/*
Conjunctiva	2/2/2	*/2/*	*/2/*	*/*/*
Chemosis	3/4/3	4/4/3	4/4/3	3/3/3

* severe edema, eyeball not assessable,

The application of the test substance caused severe damage of ophthalmic tissue including corneal opacity. Due to severe edema, eyeball was not assessable at all readings. After 8 days, the study was terminated since reversibility of the findings was not expected.

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Reference 2

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro eye irritation study does not need to be conducted because adequate data from an in vivo eye irritation study are available

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation/corrosion

For the assessment of the skin irritation/corrosion potential of the test substance a weight of evidence approach was applied, using the Corrositex in vitro skin corrosion test (BASF SE, 2011) and an in vivo study in rabbits (BASF AG, 1979d).

In the skin irritation study, Vienna white rabbits were exposed to the undiluted test substance for 3 minutes (4 animals) and 1 hour (2 animals) under occlusive conditions. Readings were performed directly after exposure and after 1, 2, and 8 days post exposure. After exposure for 3 minutes, necrotic changes (irreversible full thickness necrosis) were observed in 3/4 rabbits 8 days after application (BASF AG, 1979d). The in vivo study revealed a corrosive potential of the test substance, but due to a lacking reading point 1 hour after the 3 minutes exposure, an accurate classification (Cat 1A or 1B) was not possible. Therefore the in vitro Corrositex skin corrosion test was performed according OECD TG 435 and GLP, confirming the corrosive potential of the test substance and providing more information for the classification of the test substance (BASF SE, 2011). The break through time in this membrane barrier test was 6:41 min, indicating that the test substance has an intermediate corrosive potential and should be assigned to the skin corrosivity subcategory 1B as specified in OECD TG 435 (adopted 19 July 2006) and the test system manufacturer. The results of the negative, positive, and historical control data confirmed the validity of the test performance.

Eye irritation

Two in vivo studies in rabbits were available for the assessment of the eye irritating potential of the test substance (BASF AG, 1979e; BASF AG, 1956), which were performed using methods comparable to relevant guidelines.

In the eye irritation key study, 100 µL of the undiluted test substance was applied to the right conjuntival sac of three rabbits. The left eye was left untreated and served as a control. The substance was not washed out. The application of the test substance caused severe damage of ophthalmic tissue including corneal opacity. Due to severe edema, the eyeball was not assessable at all readings. After 8 days, the study was terminated since reversibility of the findings was not expected (BASG AG, 1979e).

The supporting study (BASF AG, 1956) tested undiluted DMD using two rabbits. The test substance produced strong redness, corneal opacity, purulent lacrimation and scabbing. Depilation was observed at the area around the treated eye. The observed severe corneal opacity was considered to be an irreversible effect to ophthalmic tissue.

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

The available data for skin irritation/corrosion and eye irritation/corrosion are reliable and suitable for classification purposes under Annex I of Regulation (EC) No 1272/2008. Based on this data, 2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine) is considered to be classified for skin corrosion cat.1B and for eye damaging properties (H314) under Regulation (EC) No 1272/2008, as amended for the twelfth time in Regulation (EU) 2019/521. However, 2,2'-dimethyl-4,4'-methylenebis(cyclohexylamine) is listed in Annex VI of Regulation (EC) No 1272/2008 with cat. 1A for skin corrosion (H314). Therefore, the more strict classification will be used in the EU.