Reaction mass of (1S,6R)-3,7,7-trimethylbicyclo[4.1.0]hept-2-ene and (1R,6S)-3,7,7-trimethylbicyclo[4.1.0]hept-2-ene

Endpoint summary

Description of key information

DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances.

In GLP in vitro studies using Episkin model, DELTA-3-CARENE led to a cell viability of 29.8 ± 1.3 %.

Under the test conditions, DELTA-3-CARENE is classified as irritating to skin, R38, according to Directive 67/548/EEC and in category 2 according to CLP Regulation (EC) N° 1272/2008.

DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances. Therefore, DELTA-2-CARENE is classified as irritating to skin, R38, according to Directive 67/548/EEC and in category 2 according to CLP Regulation (EC) N° 1272/2008.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances.

Reason / purpose for cross-reference:

read-across source

Irritation / corrosion parameter:

other: other: viability % (MTT assay)

Value:

29.8

Remarks on result:

other:

Remarks:

Basis: mean. Time point: 15 min. Reversibility: no data. Remarks: ± 1.3. (migrated information)

Negative control (PBS+): mean OD = 0.821

Positive control (5% SDS): % viability (MTT assay) = 18.7 ± 3.0

Test item: % viability (MTT assay) = 29.8 ± 1.3

Table 1: MTT conversion assay in living epidermis

		O.D. 1	O.D. 2	Mean	Standard deviation	Viability %	Mean Viability %	Standard deviation
Negative control	Epidermis 1	0.768	0.808	0.788	0.028	96.0	100	0.044
	Epidermis 2	0.855	0.864	0.860	0.006	104.7
	Epidermis 3	0.819	0.811	0.815	0.006	99.3
Positive control	Epidermis 1	0.124	0.145	0.135	0.015	16.4	18.7	0.030
	Epidermis 2	0.158	0.131	0.145	0.019	17.6
	Epidermis 3	0.191	0.172	0.182	0.013	22.1
Test item	Epidermis 1	0.249	0.265	0.257	0.011	31.3	29.8	0.013
	Epidermis 2	0.236	0.236	0.236	0.000	28.8
	Epidermis 3	0.230	0.254	0.242	0.017	29.5

Interpretation of results:

irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the test conditions, delta-3-carene is classified as irritating to skin, R38, according to Directive 67/548/EEC and in category 2 according to CLP Regulation (EC) N° 1272/2008.
DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances. Therefore, DELTA-2-CARENE is classified as irritating to skin, R38, according to Directive 67/548/EEC and in category 2 according to CLP Regulation (EC) N° 1272/2008.

Executive summary:

A GLP study conducted in vitro with human epidermis model EPISKIN was performed to assess the irritancy potential of delta-3-carene (method similar to ECVAM protocol version 1.8 of February 2009). 10 µL of the test item was applied directly on epidermis for 15 min on 3 epidermis. Positive control was 10 µL of 5% (w/v) SDS solution and negative control was 10 µL of PBS (each tested on 3 epidermis). MTT conversion assay was peformed to evaluate the percentage of cellular viability of the epidermis. Positive control had a percentage of cell viability of 18.7± 3.0 and test item 29.8 ± 1.3. As the percentage of cell viability is ≤ 50 %, the test item is considered to be irritating for skin.

Delta-3-carene is classified as irritating to skin, R38, according to Directive 67/548/EEC and in category 2 according to CLP Regulation (EC) N° 1272 /2008.

Therefore, DELTA-2-CARENE is classified as irritating to skin, R38, according to Directive 67/548/EEC and in category 2 according to CLP Regulation (EC) N° 1272/2008.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

DELTA-3-CARENE (source substance) and DELTA-2-CARENE (target substance) are two structurally related substances.

In GLP in vitro studies using Episkin model, exposure of epidermis to delta-3-carene for 15 min lead to a cell viability, measured by MTT conversion, of 29.8 ± 1.3 %.

In a recent GLP in vivo eye irritation study on delta-3-carene performed according to OECD Guideline 405, instillation of delta-3-carene resulted in moderate redness of the conjunctivae associated with severe chemosis in all treated animals after 1 hour of instillation. The irritation completely resolved within 8 days. Mean individual scores at 24, 48 and 72 h after exposure for the 3 rabbits were 0, 0, 0 for cornea score; 0, 0, 0 for iris score; 2, 1.33, 1.33 for conjunctivae score and 2, 1.33, 1 for chemosis score.

Justification for selection of skin irritation / corrosion endpoint:
Only one study available on the registered substance

Justification for selection of eye irritation endpoint:
Only one study available on the registered substance

Effects on skin irritation/corrosion: irritating

Justification for classification or non-classification

As the percentage of cell viability obtained in Episkin model was ≤ 50 % for delta-3-carene, it is considered to be irritating to skin. Under the test conditions, delta-3-carene is classified as irritating to skin, R38, according to the criteria of Annex VI to the Directive 67/548/EEC and category 2 according to CLP Regulation (EC) N° 1272/2008.

delta-3 -Carene gave reversible irritating effects on rabbit eyes with irritation scores not high enough to lead to classification according to the criteria of Directive 67/548/EEC and CLP Regulation (EC) N° 1272/2008. Therefore, delta-3-carene is not classified for eye irritation according to Directive 67/548/EEC and CLP Regulation (EC) N° 1272/2008.