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Description of key information

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
100
Absorption rate - dermal (%):
100
Absorption rate - inhalation (%):
100

Additional information

Introduction:

The acute oral and dermal toxicity of Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]- is low, with LD50 being higher than 5000 mg/kg body weight for the oral and higher than 2000 mg/kg body weight for the dermal application. Therefore, an extensive toxicokinetic assessment is considered of limited value. An assessment of the anticipated toxicokinetic behaviour of Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]- is given by an expert statement by K. Groen, Ph.D a staff member of NOTOX (TS 69579; NOTOX project 195097).

Absorption:

Because Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]- is a liquid and the water solubility of the compound is relatively high (830 - 860 mg/l), intestinal exposure was not considered a rate-limiting factor for the absorption of the compound from the gastro-intestinal tract. Based on the stability data, its is anticipated that in the stomach (pH 1 -2) Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]- is partially hydrolysed. A worst case absorption rate for dermal, oral and inhalation was taken as 100%.

Since it is generally accepted that substances with log Pow ranging from 0.1 to 6 penetrate the skin easily, it is anticipated that Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]- with a log Pow = 4.1 - 5.0 (20°C) will penetrate the skin. This assumption is supported by the observations during the acute dermal toxicity study, where very slight edema and erythema was noticed.

Metabolism:

Both phase-I and phase-II metabolic enzymes may be involved in the metabolism of Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]-. Probably, deethylation of the silane group will be extensive. Furthermore, ring opening at the oxygen is anticipated. All of these metabolic steps are expected to lead to more water soluble and less toxic metabolites. The oxidative deethylation reaction requires enzymes that utilize the coenzyme NADPH, the cytochrome P-450 system and an NADPH regenerating system to provide the necessary oxygen and electrons to produce polar metabolites. Phase-II metabolism will probably be limited to sulphation and glucuronidation of the phase-I metabolites. The conjugates are expected to be easily eliminated via the kidneys.

Distribution:

Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]- is anticipated to distribute to body water, with limited distribution into fatty tissues.

Conclusion:

Based on the expected kinetic behaviour in the body, as described above, the systemic exposure to Silane, triethoxy[2 -(7 -oxabicyclo[4.1.0]hept-3yl)ethyl]- will be limited and no accumulation in the body after prolonged exposure is anticipated. The anticipated kinetic behaviour is supported by the acute and subchronic toxicity data.