5H-Cyclopenta[h]quinazoline, 6,7,8,9-tetrahydro-7,7,8,9,9-pentamethyl-

Endpoint summary

Description of key information

- Skin sensitisation: the substance is a skin sensitiser based on the LLNA (OECD TG 429).

- Respiratory sensitisation: the substance is not a respiratory sensitiser based on absence of human data and it does not belong to a group of respiratory sensitisers.

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

For skin sensitisation several tests were performed: an LLNA and three HRIPT studies. In view of the absence of a dose response in the LLNA this study was used to classify the substance as a sensitiser. The HRIPT studies performed at 10, 15 and 20% did not show skin sensitisation and based on this the substance is considered a 1B sensitiser. In the HRIPT with 20% slight irritation was seen in 3/103 subjects. To take into account this irritation reaction the HRIPT the NOEC is set to 15% and used for the risk assessment. 

LLNA according to OECD 429: A study was performed to assess the skin sensitisation potential of the test item in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. This study was conducted according OECD TG 429 and GLP principles. Following a preliminary screening test in which no clinical signs of toxicity were noted at a concentration of 50% w/w, this concentration was selected as the highest dose investigated in the main test of the Local Lymph Node Assay. Three groups, each of five animals, were treated with 50 µl (25 µl per ear) of the test item as a solution in acetone/olive oil 4:1at concentrations of 50%, 25% or 10% w/w. A further group of five animals was treated with acetone/olive oil 4:1 alone. A concurrent positive control test, using a group of five animals, was performed with the known sensitiser,α‑Hexylcinnamaldehyde, tech., 85%, at a concentration of 25% v/v in acetone/olive oil 4:1. Results showed the Stimulation Index expressed as the mean radioactive incorporation for each treatment group divided by the mean radioactive incorporation of the vehicle control group are as follows: the stimulation index was 16.10; 16.88; 9.15 and 10.63 for the concentrations 10%, 25%, 50% w/w in acetone/olive oil 4:1 and the positive control respectively. All results showed a positive result. At the 50% concentration light brown residues of the skin were seen, indicating that this % was possibly too high, though not noticed in the preliminary test. α-Hexylcinnamaldehyde, 85% gave a Stimulation Index of greater than 3 when tested at a concentration of 25% v/v in acetone/olive oil 4:1.The substance was considered to be a sensitiser under the conditions of the test, due to the absence of a dose-response the study receives Kl. 2.

HRIPT test: 10% w/w EtOH:DEP (1:3): 112 subjects participated in evaluating the potential of the substance to elicit dermal irritation and/or induce sensitisation. The substance was applied under an occlusive patch to the upper back of each subject and was allowed to remain in direct skin contact for a period of 24 hours. Patches were applied to the same site on Monday, Wednesday, and Friday for a total of 9 applications during the Induction Period. The sites were graded by a CRL technician for dermal irritation 24 hours after removal of the patches by the subjects on Tuesday and Thursday and 48 hours after removal of the patches on Saturday. Following approximately a 2-week rest period, challenge patches were applied to previously untreated test sites on the back. After 24 hours, the patches were removed by a CRL technician and the test sites were evaluated for dermal reactions. The test sites were re-evaluated at 48 and 72 hours. Subjects exhibiting reactions during the Challenge Phase of the study may have been asked to return for a 96-hour reading. 107 subjects completed the study. Results: The substance (10% w/w EtOH:DEP(1:3) did not demonstrate a potential for eliciting dermal irritation or sensitisation under the following test conditions: 0.2 mL of the substance applied to a 3.63 cm^2 occlusive patch. Application of 0.2 mL with 10% of the substance at 3.63 cm^2 was not sensitising under the conditions of 107 subjects. This results in 200mg*0.10/ 3.63 cm^2= 5.5 mg (5500 µg)/ cm^2

HRIPT test: 15% w/w EtOH:DEP (1:3): 112 subjects participated in evaluating the potential of (15% EtOH: DEP(1:3)) to elicit dermal irritation and/or induce sensitisation. The substance was applied under an occlusive patch to the upper back of each subject and was allowed to remain in direct skin contact for a period of 24 hours. Patches were applied to the same site on Monday, Wednesday, and Friday for a total of 9 applications during the Induction Period. The sites were graded by a CRL technician for dermal irritation 24 hours after removal of the patches by the subjects on Tuesday and Thursday and 48 hours after removal of the patches on Saturday

Following approximately a 2-week rest period, challenge patches were applied to previously untreated test sites on the back. After 24 hours, the patches were removed by a CRL technician and the test sites were evaluated for dermal reactions. The test sites were re-evaluated at 48 and 72 hours. Subjects exhibiting reactions during the Challenge Phase of the study may have been asked to return for a 96-hour reading. 106 subjects completed the study. Results: The substance identified as (15% EtOH: DEP(1:3)) did not demonstrate a potential for eliciting dermal irritation or sensitisation under the following test conditions: 0.2 mL of the substance applied to a 3.63 cm^2 occlusive patch. Results: Application of 0.2 mL with 15% of the substance at 3.63 cm^2 was not sensitising under the conditions of 106 subjects. This results in (200 mg*0.15) / 3.63 cm^2= 8.3 mg (8300 µg)/ cm^2

HRIPT test: 20% w/w EtOH:DEP (1:3): 112 subjects participated in evaluating the potential of the substance (20% w/w in EtOH:DEP (1:3)) to elicit dermal irritation and/or induce sensitisation. The substance was applied under an occlusive patch to the upper back of each subject and was allowed to remain in direct skin contact for a period of 24 hours. Patches were applied to the same site on Monday, Wednesday, and Friday for a total of 9 applications during the Induction Period. The sites were graded by a CRL technician for dermal irritation 24 hours after removal of the patches by the subjects on Tuesday and Thursday and 48 hours after removal of the patches on Saturday. Following approximately a 2-week rest period, challenge patches were applied to previously untreated test sites on the back. After 24 hours, the patches were removed by a CRL technician and the test sites were evaluated for dermal reactions. The test sites were re-evaluated at 48 and 72 hours. Results: Subjects exhibiting reactions during the Challenge Phase of the study may have been asked to return for a 96- hour reading. 103 subjects completed the study. 3 subjects exhibited reactions during the Challenge Phase. The reactions observed were likely to be irritation and delayed irritation, since there was no oedema and/or itching. All three subjected have been asked to return for a Re-Challenge Test but one subject declined. The reactions observed during the Challenge Phase of the RIPT on subjects were not confirmed during the Re­ Challenge Test under occlusive conditions. It was concluded that the substance (20% w/w in EtOH:DEP (1 :3)) did not demonstrate a clinically significant potential for eliciting dermal irritation or sensitisation under the following test conditions: 0.2 mL of the substance applied to a 3.63 cm^2 occlusive patch. Application of 0.2 mL with 20% of the substance at 3.63 cm^2 was not sensitising under the conditions of 103 subjects. This results in (200mg*0.20 / 3.63 cm^2= 11.0 mg (11000 µg)/ cm^2. 

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Justification for classification or non-classification

The LLNA indicates that the test substance is a skin sensitiser. In absence of a dose response in this test the potency and no effect level cannot be derived from the LLNA (Kl. 2). For this purpose the HRIPT with 20% is used for assessment. The substance can be classified as Skin Sens 1B, as 0.2 mL of the substance (20% of the substance) is applied to 3.63 cm2 skin surface, which is substantially above the cut-off value of 500 µg/cm2 (11000 µg/cm2 without density correction) in accordance with EU CLP (EC no. 1272/2008).

Respiratory sensitisation: the substance is not considered a respiratory sensitiser because human data are not available to assign such a classification. In addition, the substance has no structural feature indicating respiratory sensitisation.