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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: methacrylate esters
• the metabolism pathway leads to comparable products (methacrylic acid and short chain alcohol).

Therefore, read-across from the existing (eco)toxicity studies on the source substances is considered as an appropriate adaptation to the standard information requirements of REACH regulation

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see crossreference “Justification for read-across”

3. ANALOGUE APPROACH JUSTIFICATION
see crossreference “Justification for read-across”

4. DATA MATRIX
see crossreference “Justification for read-across”
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across: supporting information
Test organisms (species):
activated sludge of a predominantly domestic sewage
Test type:
static
Water media type:
freshwater
Total exposure duration:
3 h
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
32 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
72.8 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: 62.6-84.7 mg/L
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
557 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: 495-634 mg/L
Validity criteria fulfilled:
yes
Conclusions:
The NOEC based on respiration inhibition of activated sludge is 32 mg/L. The EC10 is 72.8 mg/L. The EC50 is 557 mg/L.

Description of key information

EC10 = 72.8 mg/L; OECD Guideline 209; GLP; activated sludge respiration inhibition (static); read-across from ETMA

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
72.8 mg/L

Additional information

No data with MTMA are available for the assessment of toxicity to microorganisms. However, reliable (RL=1 - 2), relevant and adequate studies are available for the closely related source substance ETMA. A justification for read-across is given in the endpoint summary "Aquatic toxicity".

In a 3 h Respiration Inhibition Test according to OECD Guideline 209, adopted 22 July 2010, activated sludge obtained from a municipal treatment plant was exposed to ETMA at nominal concentrations of 10, 32, 100, 320 and 1000 mg/L under static conditions. In order to check the activity of the test system and the test conditions a reference test was carried out with copper (II) sulphate pentahydrate as reference item. The reference item produced the appropriate response.

The NOEC of ETMA based on respiration inhibition of activated sludge is 32 mg/L. The EC10 is 72.8 mg/L. The EC50 is 557 mg/L.

 

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