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Administrative data

Description of key information

In a seven-day range-finding study conducted to determine appropriate doses for administration in an OECD TG 422 study,  a NOAEL could not be determined for triacetoxyethylsilane due to the corrosive effects of this substance on the oesophagus and stomach (DCC, 2004).The study was not conducted to a guideline or to GLP since it was a range-finder only. 
On the basis of this result and results of the skin corrosion studies, it is concluded that it is not feasible to conduct the OECD TG 422 study, which is in agreement with the decision of the US EPA.

Key value for chemical safety assessment

Additional information

The only repeated dose toxicity data available are from a 7-day range-finding study (DCC, 2004). This 7-day range-finder study indicated that a maximum dose level of less than 20 mg/kg/day would be required for a longer duration repeated dose study in order to avoid death or obvious suffering due to the corrosivity of the hydrolysis product, acetic acid. The data provided in this range-finder study indicate a practical and humane dose range for subsequent longer term studies is below the limit of technical practicality and toxicological significance.

As a result of the corrosive findings in this study, the following was concluded regarding the full OECD TG 422 study (as reported in DCC, 2006):

"The results and concerns regarding animal welfare were discussed with the EPA and resulted in EPA's acceptance of the Sponsor's request for a reduced testing rationale for ethyltriacetoxysilane. The reduced testing rationale included not conducting the combined repeated dose toxicity with the reproductive/developmental toxicity screening test for ethyltriacetoxysilane in Sprague-Dawley rats. In addition, ethyltriacetoxysilane was reviewed at SIAM 21 where it was determined that this chemical possesses properties indicating a hazard for human health (severe irritation and corrosivity caused by acetic acid)."

In response to the EPA's acceptance of reduced testing rationale the full OECD TG 422 study was cancelled.

Justification for classification or non-classification

Triacetoxyethylsilane is not classified for specific target organ toxicity following repeated doses by any route according to Regulation 1272/2008/EC.