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

Endpoint summary

Description of key information

- Skin corrosion: The substance does not cause corossion based on OECD TG 432 and 404.

- Skin irritation: The substance does not cause skin irritation based on OECD TG 439 and 404.

- Eye irritation: The substance is not an irritant based on the OECD TG 437 and 405.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Skin irritation/corrosion (OECD TG 432): The purpose of this test is to evaluate the corrosivity potential of the substance using the EPISKIN in vitro Reconstructed Human Epidermis (RHE) Model after treatment periods of 3, 60 and 240 minutes. This study was conducted according to OECD TG 432 and GLP principles. The EPISKIN model is able to distinguish between corrosive and non-corrosive chemicals for all of the chemical types studied, and is also able to distinguish between known R35 (UN packing group I) and R34 (UN packing group II & III) substances. Duplicate tissues were treated with the substance for exposure periods of 3, 60 and 240 minutes. At the end of the exposure period the substance was rinsed from each tissue before each tissue was taken for MTT-loading. After MTT loading a total biopsy of each epidermis was made and placed into micro tubes containing acidified isopropanol for extraction of formazan crystals out of the MTT-loaded tissues. At the end of the formazan extraction period each tube was mixed thoroughly and duplicate 200 µL samples were transferred to the appropriate wells of a pre labelled 96 well plate. The optical density (OD) was measured at 562 nm (OD562). Data are presented in the form of percentage viability (MTT reduction in the substance treated tissues relative to negative control tissues). Triplicate tissues were treated with the substance for an exposure period of 15 minutes. At the end of the exposure period each tissue was rinsed before incubating for 42 hours. At the end of the post-exposure incubation period each tissue was taken for MTT-loading. The maintenance medium from beneath each tissue was transferred to pre-labelled micro tubes and stored in a freezer for possible inflammatory mediator determination. After MTT loading a total biopsy of each epidermis was made and placed into micro tubes containing acidified isopropanol for extraction of formazan crystals out of the MTT-loaded tissues. At the end of the formazan extraction period each tube was mixed thoroughly and duplicate 200 μL samples were transferred to the appropriate wells of a pre-labelled 96-well plate. The optical density was measured at 562 nm. Data are presented in the form of percentage viability (MTT reduction in the substance treated tissues relative to negative control tissues).

The relative mean viability of the substance treated tissues was 119.1% after the 15-minute exposure period and 42 hours post-exposure incubation period. The quality criteria required for acceptance of results in the test were satisfied. The substance was classified as non-irritant. The following classification criteria apply: EU DSD & CLP Not classified for Irritation. UN GHS Not classified for Irritation (category 3 cannot be determined).

 

Results: The relative mean viabilities of the substance treated tissues were: 240 minutes exposure: 121.2%, 60 minutes exposure: 111.4%, 3 minutes exposure: 111.8%. The quality criteria required for acceptance of results in the test were satisfied.

Skin irritation/corrosion (OECD TG 404): The study was performed to assess the irritancy potential of the test item to the skin of the New Zealand White rabbit, according to OECD 404 and GLP principles. A single 4-hour, semi-occluded application of the substance to the intact skin of three rabbits produced very slight erythema at two treated skin sites up to one hour after dressing removal. No evidence of skin irritation was noted at one treated skin site. The substance produced a primary irritation index of 0.0 and was classified as non-irritant to rabbit skin according to the Draize classification scheme. No corrosive or irritation effects were noted. 

The purpose of this test was to evaluate the skin irritation potential of the substance using the EPISKINTM reconstructed human epidermis model after a treatment period of 15 minutes followed by a post-exposure incubation period of 42 hours. This study was conducted according to OECD TG 439 and GLP principles. The principle of the assay was based on the measurement of cytotoxicity in reconstructed human epidermal cultures following topical exposure to the substance by means of the colorimetric MTT reduction assay. Cell viability is measured by enzymatic reduction of the yellow MTT tetrazolium salt (3-[4,5-dimethylthiazol-2- yl]-2,5-diphenyl-tetrazolium bromide) to a blue formazan salt (within the mitochondria of viable cells) in the substance treated tissues relative to the negative controls. The concentration of the inflammatory mediator IL-1αin the culture medium retained following the 42-Hour post-exposure incubation period may also be determined for substances which are found to be borderline non-irritant based upon the MTT reduction endpoint. This complimentary end-point can be used to either confirm a non-irritant result or will be used to override the non-irritant result.

Eye irritation (OECD TG 437): A study was performed to assess the ocular irritancy potential of the substance to the isolated bovine cornea. The method was designed to be compatible with OECD TG 437 and GLP principles. The substance was applied at a concentration of 20% w/v in 0.9% w/v sodium chloride solution for 240 minutes. Negative and positive control items were tested concurrently. The two endpoints, decreased light transmission through the cornea (opacity) and increased passage of sodium fluorescein dye through the cornea (permeability) were combined in an empirically derived formula to generate an In Vitro Irritancy Score (IVIS). A substance that induces an In Vitro Irritancy Score ≥ 55.1 is defined as an ocular corrosive or severe irritant. Results showed that the in vitro irritant score were 1.7, 3.2 and 73.6 for the substance, negative control and positive control, respectively. In conclusion, the substance was considered not to be an ocular corrosive or severe irritant. 

Eye irritation (OECD TG 405): The study was performed to assess the irritancy potential of the substance to the eye of the New Zealand White rabbit, according to OECD TG 405 and GLP principles. Results showed that a single application of the substance to the non-irrigated eye of three rabbits produced iridial inflammation and moderate conjunctival irritation. One treated eye appeared normal at the 48-hour observation and two treated eyes appeared normal at the 72-hour observation and with this score it is not considered an eye irritant. 

Justification for classification or non-classification

The substance does not need to be classified for skin and eye corrosion or irritation in accordance with EU CLP (EC No 1272/2008 and its amendments).