Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Toxicity to microorganisms: ASRI 3-h EC50: >100 mg/l (loading rate) (OECD 209), read-across from a structurally-related substance. Organisms were likely predominantly exposure to parent test substance.

Key value for chemical safety assessment

Additional information

There are no microorganism toxicity data available for 4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane (S2), therefore good quality data for the structurally-related substance polysulfides, bis[3-(triethoxysilyl)propyl]- (CAS 211519-85-6), have been read across.

S2 is present as a constituent in polysulfides, bis[3-(triethoxysilyl)propyl]- which is a multi-constituent substance. S2 and the other constituents of polysulfides, bis[3-(triethoxysilyl)propyl]- hydrolyse at a moderate or slow rate to structurally similar silanol products; the other hydrolysis product being ethanol. Ethanol is not expected to have adverse effects on microorganisms.

S2 and Polysulfides, bis[3-(triethoxysilyl)propyl]- are within an analogue group of substances that exhibit no evidence of significant toxicity to microorganisms.

This analogue group for the toxicity to microorganisms endpoint consists of a number of sub-classes of substances (based on structure/functionality) with different main codes (used to represent the different sub-classes). However, read-across is carried out between substances with the same main code in most cases.The table below presents microorganism toxicity data available for substances within the main code III-11 of Di- and Poly-sulfides. S2 and Polysulfides, bis[3-(triethoxysilyl)propyl]- are members of this main code.

It is therefore considered valid to read-across the results for polysulfides, bis[3-(triethoxysilyl)propyl]- to fill the data gap for the registered substance. Additional information is given in a supporting report (PFA, 2013j) attached in Section 13.

A 3hr EC50 value of >100 mg/l (exceeding the loading rate) was determined for polysulfides, bis[3-(triethoxysilyl)propyl]-.

Table: Microorganism toxicity data available for substances within the relevant main code III-11 of chemicals



Main code

Result: E(I)C50 (mg/l)

Result: NOEC (or EC10/ EC20) (mg/l)

Guideline Number

Test method





Reaction mass of 4,4,15,15-tetraethoxy-3,16-dioxa-8,9,10,11-tetrathia-4,15-disilaoctadecane and 4,4,14,14-tetraethoxy-3,15-dioxa-8,9,10-trithia-4,14-disilaheptadecane and 4,4,13,13-tetraethoxy-3,14-dioxa-8,9-dithia-4,13-disilahexadecane


>100 mg/l


OECD 209






PFA2013j: Peter Fisk Associates, STP Microorganism toxicity Main Analogue Group report, PFA.300.003.006