Registration Dossier

Administrative data

Description of key information

No studies were available to assess the skin sensitisation potential of dimethoxymethylsilane, however, data are available for the structurally related substance triethoxymethylsilane (CAS 2031-67-6).

OECD TG 406: not sensitizing

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records
Reference
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
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
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10% TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema or oedema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females).
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
10 % TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema or oedema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females).
Remarks on result:
no indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
10% TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema and oedema in any animal. Desquamation in 1 animal.
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
10% TS
No. with + reactions:
3
Total no. in group:
20
Clinical observations:
No erythema/oedema in males, Grade 1 erythema/oedema in 3 females, where subsequent histopathology revealed no signs of cell mediated delayed hypersensitivity. 7/10 males and 4/10 females showed desquamation (including the three with erythema/oedema).
Remarks on result:
no indication of skin sensitisation
Group:
positive control
Remarks on result:
not measured/tested

Signs of irritation were noted during the induction. Although macroscopic examination showed grade 1 erythema/oedema in 3 females 48 h after challenge subsequent histopathological examinations did not reveal any lesion of delayed hypersensitivity in the those animals. No noticeable cutaneous abnormality was noted in the 20 guinea pigs examined in the control group.

Interpretation of results:
other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008
Conclusions:
In a Guinea Pig Maximisation Test conducted to GLP and OECD 406 triethoxymethylsilane (source substance) was not sensitising to the skin and thus no skin sensitising potential is estimated for the target substance. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in skin sensitisation potential.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (not sensitising)
Additional information:

Studies were chosen as key when the available study was of relevance and of sufficient quality for classification and labelling and for risk assessment.

No studies were available to assess the skin sensitisation potential of dimethoxymethylsilane, however, data are available for the structurally related substance triethoxymethylsilane (CAS 2031-67-6). Both substances hydrolyse in contact with water to produce the common silanol hydrolysis product, methylsilanetriol. Therefore, it is considered that read-across between the substances is appropriate.

In a key guinea pig maximisation study conducted in compliance with GLP and according to OECD TG 406, triethoxymethylsilane was found to be a non-sensitiser. A group of ten male and ten female guinea pigs was dosed with multiple intradermal injections on day 0 following a topical application on day 7 in order to investigate sensitisation potential of triethoxymethylsilane. The topical induction consisted of a 48 hour occluded dermal exposure to 0.5 ml of the test substance in a 50% (v/v) solution in sterile codex liquid paraffin. Eleven days after topical induction, challenge dosing for detection of sensitisation was performed. For challenge dosing, an essentially non-irritating concentration (10% (v/v)) of the test material was applied under occlusion for 24 hours. Although macroscopic examination showed grade 1 erythema/oedema in 3 females 48 h after challenge subsequent histopathological examinations did not reveal any lesion of delayed hypersensitivity in those animals. Including these 3 females the sensitisation index was calculated to be 15% for the test group following rechallenge. Appropriate positive and negative controls gave expected results (Hazleton, 1992c).

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The available data on skin sensitisation of the structural analogue substance, triethoxymethylsilane (CAS 2031-67-6), do not meet the criteria for classification according to Regulation (EC) 1272/2008 or EU Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification of the registered substance.