Registration Dossier

Administrative data

Description of key information

Skin irritation (OECD 404, WoE), rabbit: not irritating (RA from CAS 2031-67-6 and CAS 1185-55-3)
Eye irritation (OECD 405, WoE), rabbit: not irritating (RA from CAS 2031-67-6 and CAS 1185-55-3)

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records
Reference
Endpoint:
skin irritation: in vivo
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
weight of evidence
Justification for type of information:
Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Irritation parameter:
erythema score
Basis:
mean
Remarks:
of 3 animals
Time point:
24/48/72 h
Score:
0.67
Max. score:
4
Reversibility:
fully reversible within: 72 h
Remarks on result:
other: CAS 1185-55-3, Hazelton, 1966
Remarks:
intact skin
Irritation parameter:
edema score
Basis:
mean
Remarks:
of 3 animals
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: not applicable
Remarks on result:
other: CAS 1185-55-3, Hazelton, 1966
Remarks:
intact skin

In a weight of evidence approach two source substances were evaluated.

In the reliable skin irritation study performed with Triethoxy(methyl)silane (CAS 2031-67-6) according to OECD TG 404 and in compliance with GLP six male New Zealand hybrid albino rabbits were exposed to 0.5 mL of the neat test material for 4 h applied onto the shaved skin via semi-occlusive dressing (Hazleton, 1992a). Skin reactions were evaluated according to the Draize scoring system 1, 24, 48 and 72 h post-application. No symptoms of systemic toxicity were observed in any animal during the test period and no mortality occurred during the course of the study. Slight erythema formation (grade 1) was observed in 5/6 animals one hour after patch removal persisting in 2/6 animals 24 h after patch removal. Erythema formation was fully reversible within 48 h after patch removal. No edema formation was observed in any animal. The mean values for erythema and edema were calculated to be 0.11 and 0, respectively.

In a further reliable skin irritation study performed with Trimethoxy(methyl)silane (CAS 1185-55-3) similar to OECD TG 404 six Albino rabbits of unknown gender were exposed to 0.5 mL of the neat test material for 24 h applied onto the intact (3 animals) and abraded (3 animals) skin via occlusive dressing (Hazleton, 1966). Skin reactions were evaluated according to the Draize scoring system 24 and 72 h post-application. No symptoms of systemic toxicity were observed in any animal during the test period and no mortality occurred during the course of the study. Slight erythema formation (grade 1: mean of 3 animals, intact skin) was recorded 24 h after patch removal which was fully reversible within 72 h. No experimental data is available for the 48 h time point, thus the 48 h values were assumed to be the same as those at 24 h (worst case assumption). No edema formation was recorded at the 24 and 72 h observation time point. The mean values for erythema and edema (intact skin) were calculated to be 0.67 and 0, respectively.

Interpretation of results:
other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008
Conclusions:
Reliable studies from two source substance are availabe to evaluate the skin irritation potential. Both source substances are shown to be not skin irritating. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in skin irritation potential.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records
Reference
Endpoint:
eye irritation: in vivo
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Remarks:
Summary of available data used for the endpoint assessment of the target substance
Adequacy of study:
weight of evidence
Justification for type of information:
Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Irritation parameter:
cornea opacity score
Basis:
mean
Remarks:
of 6 animals
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: not applicable
Remarks on result:
other: CAS 2031-67-6, Bushy Run Research Center, 1981
Irritation parameter:
iris score
Basis:
mean
Remarks:
of 6 animals
Time point:
24/48/72 h
Score:
0
Max. score:
2
Reversibility:
other: not applicable
Remarks on result:
other: CAS 2031-67-6, Bushy Run Research Center, 1981
Irritation parameter:
chemosis score
Basis:
mean
Remarks:
of 6 animals
Time point:
24/48/72 h
Score:
0
Max. score:
4
Reversibility:
other: not applicable
Remarks on result:
other: CAS 2031-67-6, Bushy Run Research Center, 1981
Irritation parameter:
conjunctivae score
Basis:
mean
Remarks:
of 6 animals
Time point:
24/48/72 h
Score:
0.06
Max. score:
3
Reversibility:
fully reversible within: 48 h
Remarks on result:
other: CAS 2031-67-6, Bushy Run Research Center, 1981

In a weight of evidence approach two source substances were evaluated.

In the reliable eye irritation study with Triethoxy(methyl)silane (CAS 2031-67-6) performed similar to OECD TG 405 (Bushy Run Research Center, 1981) 0.1 mL of the neat test material was instilled in the eye of six New Zealand White rabbits of unknown gender. The eyes were examined and the changes were graded according to the Draize scoring system 1, 24, 48 and 72 h and 4, 7, 10 and 14 days post-application. No symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred during the course of the study. No corneal opacity was recorded in any animal during the entire study period. Iridial irritation (grade 1) was observed in 2/6 animals 1 h post-application of the test material but was fully reversible within 24 h. Chemosis (grade 1) was recorded in 1/6 animals 1 h post-application of the test material but was also fully reversible within 24 h. Conjunctival irritation (grade 1) was observed in 6/6 animals 1 h post-application of the test material and persisted in 1/6 animals after 24 h. This effect was fully reversible within 48 h post-application of the test material. The mean values for corneal opacity, iridial and conjunctival irritation and chemosis were 0, 0, 0.06 and 0, respectively.

In a further reliable eye irritation study with Trimethoxy(methyl)silane (CAS 1185-55-3) performed according to OECD TG 405 and in compliance with GLP (Hoechst, 1991) 0.1 mL of the neat test material was instilled in the eye of three New Zealand White rabbits of unknown gender. The eyes were examined and the changes were graded according to the Draize scoring system 24, 48 and 72 h post-application. No symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred during the course of the study. Mild to moderate conjunctival redness and discharge (grade 1) were observed in 3/3 animals 1 h post-instillation. Mild chemosis (grade 1) was also observed at this time point. All effects were fully resolved within 24 h. No further corneal opacity, iridial and conjunctival irritation and chemosis were recorded in all animals during the remaining study period. Thus, the mean values for corneal opacity, iridial and conjunctival irritation and chemosis were 0.

Interpretation of results:
other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008.
Conclusions:
Reliable studies from two source substance are availabe to evaluate the eye irritation potential. Both source substances are shown to be not skin irritating.
As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in eye irritation potential.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not irritating)

Respiratory irritation

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

No data on skin or eye irritation is avaiable for diethoxy(dimethyl)silane(CAS 78 -62 -6).Therefore, the risk assessment was performed based on the available data from the source substance trimethoxy(methyl)silane (CAS 1185 -55 -3) and triethoxy(methyl)silane (2031 -67 -6). In accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 “Grouping of substances and read across” and following the Read across assessment framework (RAAF, ECHA 2017) read across from analogue substances has been applied to support the human health hazard assessment of diethoxy(methyl)silane (CAS 78 -62 -6). Further details are provided in the analogue justification attached to the respective target entry.

For assessment of skin and eye irritating properties of Diethoxy(dimethyl)silane (CAS 78-62-6) a weight of evidence approach was applied using the structural analogues Triethoxy(methyl)silane (CAS 2031-67-6) and Trimethoxy(methyl)silane (CAS 1185-55-3).

 

 

Skin irritation

In the reliable skin irritation study performed with Triethoxy(methyl)silane (CAS 2031-67-6) according to OECD TG 404 and in compliance with GLP six male New Zealand hybrid albino rabbits were exposed to 0.5 mL of the neat test material for 4 h applied onto the shaved skin via semi-occlusive dressing (Hazleton, 1992a). Skin reactions were evaluated according to the Draize scoring system 1, 24, 48 and 72 h post-application. No symptoms of systemic toxicity were observed in any animal during the test period and no mortality occurred during the course of the study. Slight erythema formation (grade 1) was observed in 5/6 animals one hour after patch removal persisting in 2/6 animals 24 h after patch removal. Erythema formation was fully reversible within 48 h after patch removal. No edema formation was observed in any animal. The mean values for erythema and edema were calculated to be 0.11 and 0, respectively.

In a further reliable skin irritation study performed with Trimethoxy(methyl)silane (CAS 1185-55-3) similar to OECD TG 404 six Albino rabbits of unknown gender were exposed to 0.5 ml of the neat test material for 24 h applied onto the intact (3 animals) and abraded (3 animals) skin via occlusive dressing (Hazleton, 1966). Skin reactions were evaluated according to the Draize scoring system 24 and 72 h post-application. No symptoms of systemic toxicity were observed in any animal during the test period and no mortality occurred during the course of the study. Slight erythema formation (grade 1: mean of 3 animals, intact skin) was recorded 24 h after patch removal which was fully reversible within 72 h. No experimental data is available for the 48 h time point, thus the 48 h values were assumed to be the same as those at 24 h (worst case assumption). No edema formation was recorded at the 24 and 72 h observation time point. The mean values for erythema and edema (intact skin) were calculated to be 0.67 and 0, respectively.

 

Eye irritation

In the reliable eye irritation study with Triethoxy(methyl)silane (CAS 2031-67-6) performed similar to OECD TG 405 (Bushy Run Research Center, 1981) 0.1 mL of the neat test material was instilled in the eye of six New Zealand White rabbits of unknown gender. The eyes were examined and the changes were graded according to the Draize scoring system 1, 24, 48 and 72 h and 4, 7, 10 and 14 days post-application. No symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred during the course of the study. No corneal opacity was recorded in any animal during the entire study period. Iridial irritation (grade 1) was observed in 2/6 animals 1 h post-application of the test material but was fully reversible within 24 h. Chemosis (grade 1) was recorded in 1/6 animals 1 h post-application of the test material but was also fully reversible within 24 h. Conjunctival irritation (grade 1) was observed in 6/6 animals 1 h post-application of the test material and persisted in 1/6 animals after 24 h. This effect was fully reversible within 48 h post-application of the test material. The mean values for corneal opacity, iridial and conjunctival irritation and chemosis were 0, 0, 0.06 and 0, respectively.

In a further reliable eye irritation study with Trimethoxy(methyl)silane (CAS 1185-55-3) performed according to OECD TG 405 and in compliance with GLP (Hoechst, 1991) 0.1 mL of the neat test material was instilled in the eye of three New Zealand White rabbits of unknown gender. The eyes were examined and the changes were graded according to the Draize scoring system 24, 48 and 72 h post-application. No symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred during the course of the study. Mild to moderate conjunctival redness and discharge (grade 1) were observed in 3/3 animals 1 h post-instillation. Mild chemosis (grade 1) was also observed at this time point. All effects were fully resolved within 24 h. No further corneal opacity, iridial and conjunctival irritation and chemosis were recorded in all animals during the remaining study period. Thus, the mean values for corneal opacity, iridial and conjunctival irritation and chemosis were 0.

In conclusion, based on the available data from two structural analogues it was concluded that Diethoxy(dimethyl)silane (CAS 78-62-6) is neither skin nor eye irritating.


Justification for classification or non-classification

The available data on skin and eye irritation from structural analogues indicate that Diethoxy(dimethyl)silane do not meet the criteria for classification according to Regulation (EC) No 1272/2008, and are therefore conclusive but not sufficient for classification.