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Toxicity to microorganisms

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Description of key information

Toxicity to microorganisms: 3 hour EC50 >1000 mg/l OECD 209), read-across from a structurally related substance.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L
EC10 or NOEC for microorganisms:
1 000 mg/L

Additional information

There are no reliable microorganism toxicity data available for 3-[tris(acetoxy)silyl]propyl methacrylate (CAS 51772-85-1), therefore good quality data for the structurally-related substance, 3-trimethoxysilylpropyl methacrylate (CAS 2530-85-0), have been read across. Both substances share the same silanol hydrolysis product, 3-(trihydroxysilyl)propyl methacrylate. The other hydrolysis products are acetic acid and methanol, respectively.

Methanol does not have adverse effects on microorganisms (OECD, 2004).

Acetic acid does not have adverse effects on microorganisms (sodium acetate is frequently used as the control in biodegradation studies) (OECD 1992).

3-[Tris(acetoxy)silyl]propyl methacrylate (CAS 51772-85-1) and 3-trimethoxysilylpropyl methacrylate (CAS 2530-85-0) are within an analogue group of substances within which, in general, there is 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 sub-class III-02 of acrylate functionality group(s) in side chain after any very rapid hydrolysis has been accounted for. 3-[Tris(acetoxy)silyl]propyl methacrylate (CAS 51772-85-1) and 3-trimethoxysilylpropyl methacrylate (CAS 2530-85-0) are both members of this sub-class.

It is therefore considered valid to read-across the results for 3-trimethoxysilylpropyl methacrylate (CAS 2530-85-0) to fill the data gap for the registered substance. Additional information is given in a supporting report (PFA, 2013j) attached in Section 13.

Table: Microorganism toxicity data available for substances within the relevant sub-class III-02 of chemicals

CAS

Name

Main code

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

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

Guideline Number

Test method

Duration

Reliability

002530-85-0

3-trimethoxysilylpropyl methacrylate

III-02

>1000

1000 mg/l

OECD 209; EC C.11

ASRI

 

3 h

1

005577-72-0

2-Propenoic acid, 2-methyl-, (triethoxysilyl)methyl ester – Pre-hydrolysed (test substance is hydrolysis products)

III-02

>1000

EC20 >1000

OECD 209; 87/302/EC

ASRI

 

3 h

1

003978-58-3

Methacryloxymethyl(diethoxy)methylsilane – Pre-hydrolysed (test substance is hydrolysis products)

III-02

>1000

EC20 >1000

OECD 209; 87/302/EC

ASRI

 

3 h

1

 

In the study with 3-trimethoxysilylpropyl methacrylate (CAS 2530-85-0), an activated sludge respiration inhibition 3 hour EC50 value of >1000 mg/l was reported.

References:

OECD (1992): OECD Guideline for testing of chemicals, Number 301, Ready biodegradability, adopted 17 July 1992.

OECD (2004): SIDS Initial Assessment Report for SIAM 19, Berlin, Germany, 18-20 October 2004, Methanol, CAS 67-56-1.

PFA, 2013j, Peter Fisk Associates, STP Microorganism toxicity Main Analogue Group report, PFA.300.003.006