Registration Dossier
Registration Dossier
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EC number: 477-700-1 | CAS number: 883794-93-2
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
No studies are available. Based on molecular structure, molecular weight, and octanol-water partition coefficient it can be expected that the submission substance likely to be absorbed via the oral route, but not via the dermal and inhalation routes. Hydrolysis might occur after ingestion, but significant hydrolysis in contact with skin or in contact with lung tissue is not expected. Due to the high molecular weight, the registered substance is not expected to be widely distributed in the body. Excretion via the renal pathway is considered favoured. Thus, bioaccumulation potential is expected to be low.
Key value for chemical safety assessment
- Bioaccumulation potential:
- low bioaccumulation potential
Additional information
There are no studies available in which the toxicokinetic properties of the registered substance Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulfide have been investigated. Therefore, in accordance with Annex VIII, Column 1, Item 8.8 of Regulation (EC) 1907/2006 and with Guidance on information requirements and chemical safety assessment Chapter R.7c: Endpoint specific guidance (ECHA, 2012), the toxicokinetic behaviour assessment was assessed from its physico-chemical properties and the available toxicology studies.
The molecular weight of Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulfide is 497 g/mol and the predicted log Kow is -0.2257. The registered substance hydrolyses in contact with water with predicted half-lives of 1.1-24, 13-155, 28-504 and 0.04-340 min at pH 4, 5, 7 and 9, respectively, under formation of the smaller and water soluble hydrolysis products bis(3-(trihydroxysilyl)propyl)disulphide (silanol hydrolysis product) and 2,2’,2’’-nitrilotriethanol (amino alcohol hydrolysis product). Significant hydrolysis in contact with skin or, following inhalation, in contact with lung tissue is not expected. However, after ingestion part of the substance might be hydrolysed in the acidic environment of the stomach.
Absorption
Oral:Due to the high molecular weight the registered substance is not favourable for absorption, but the moderate log Kow supports passive diffusion through biological membranes.
In an acute oral toxicity study with Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulfide, there was no mortality and no signs of systemic effects were noted in in rats dosed with 2000 mg/kg bw. In contrast, repeated dose toxicity data revealed effects on kidneys in rats after oral dosage with the registered substance. The registered substance can therefore be concluded to be at least in part absorbed via the oral route.
Inhalation: There are no data on inhalation toxicity of Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulphide available. The physical state of the registered substance is a powder with 12% of the particles < 2 µm and 88% of the particles ≥ 2 - ≤ 100 µm. Therefore, the substance is respirable and contains a particle fraction that might reach the alveolar region. However, highly controlled conditions are required during manufacturing due to hydrolysis of the substance and corrosive nature of the chlorosilane from which it is manufactured. Following production, the substance is fixed in a matrix by embedding in polymer, and the commercial product is a granulated material with granulate size of approx. 1 cm in length and approx. 0.4 cm in diameter. Thus, the commercial product is not inhalable. Therefore, inhalation of the registered substance and consequently respiratory absorption is unlikely.
Dermal: The low log Kow of >0 of Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulphide suggests that poor lipophilicity will limit absorption through the stratum corneum and hence dermal absorption. Additionally, the high molecular weight indicates that the molecule is too large to be dermally absorbed. Data from the available key acute dermal toxicity study support the assumption that the registered substance is not absorbed via the dermal route. Rats exposed to a dermal dose of 5000 mg/kg bw did not show any signs of systemic toxicity, indicating that the substance is either of low toxicity and/or has low potential to be absorbed by the dermal route.
Distribution
The high molecular weight and the log Kow <0 of Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulphide suggest that the registered substance unlikely distributes widely through the body and into cells.
Metabolism
The registered substance hydrolyses in contact with water (calculated half-life is 28-504 min at pH 7 and 25 °C), generating bis(3-(trihydroxysilyl)propyl)disulphide and 2,2’,2’’-nitrilotriethanol. The latter is known not to undergo metabolism, but there are no data regarding the enzymatic metabolism of Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulphide or bis(3-(trihydroxysilyl)propyl)disulphide. Genetic toxicity tests in vitro showed no observable difference in effects with and without metabolic activation for Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulphide.
Excretion
The high molecular weight of Bis(2,8,9-Trioxa-5-aza-1-silabicyclo(3.3.3)undecane-1-propane-)disulphide indicates that excretion via bile is favourable. However, the log Kow <0 suggest that the registered substance is hydrophilic enough to be excreted into the urine. Moreover, the registered substance, as well as its hydrolysis products exhibit ionisable molecular structures, which is favourable for renal excretion. This is in line with data from the available repeated dose toxicity study, which revealed effects on kidneys in rats after oral dosage with the registered substance. The registered substance can therefore be concluded to be at least in part excreted via the renal pathway.The bioaccumulation potential is therefore expected to be low.
References:
ECHA (2012). European Chemicals Agency. Guidance on information requirements and chemical safety assessment, Chapter R.7c: Endpoint specific guidance, Version 1.1 November 2012.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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