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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 18 to 20 February 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other:
Remarks:
The study was performed acording to a recognised guideline and was GLP compliant.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test
Qualifier:
according to
Guideline:
other: ISO 8192-1986 requirement (E)
GLP compliance:
yes
Analytical monitoring:
no
Details on sampling:
Not applicable
Test organisms (species):
activated sludge
Details on inoculum:
The activated sludge used was obtained from the laboratory sewage treatment plant. It was not pre-treated. The concentration of the inoculum was 6 g/L TS. Autooxidation was 10000 mg/L.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
3 h
Post exposure observation period:
Not applicable
Hardness:
Not applicable
Test temperature:
Not reported
pH:
Not reported
Dissolved oxygen:
Not applicable
Salinity:
Not applicable
Nominal and measured concentrations:
The following nominal test concentrations were used: 180, 320, 560, 1000, 1800 mg/L.
Details on test conditions:
A defined amount of activated sludge was mixed with synthetic Nährlösug the respiration rate was measured. This respiration rate was compared with those measured in test preparations with different concentrations of test substance.
Reference substance (positive control):
yes
Remarks:
3, 5 - dichlorophenol
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
855 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Results with reference substance (positive control):
No results stated.
Reported statistics and error estimates:
Not reported.

Table 1: Respiration and Inhibition of Benzylacetate

Test Concentration (mg/L)  Respiration Rate (mg/L.h)  % Inhibition  
180  33.0  0.0 
320  32.0  0.9 
560  25.5  21.1 
1000  11.0  65.9 
1800  3.0  90.7 

The test concentrations result from the use amounts of audit and were not verified analytically.

The EC-values can be found in the graph given below.

Validity criteria fulfilled:
yes
Conclusions:
A study was performed to assess the effects of benzyl acetate on microorganisms. The method followed that described in the ISO 8192-1986 requirement E guideline (equivalent to OECD 209). The EC50 value was 855 mg/L.
Executive summary:

A study was performed to assess the effects of benzyl acetate on microorganisms. The method followed that described in the ISO 8192-1986 requirement E guideline (equivalent to OECD 209).

Nominal exposure concentrations were 180, 320, 560, 1000 and 1800 mg/L.  Respiration rates were 33.0, 32.0, 25.5, 11.0 and 3.0 mg/L.h and the % inhibition values were 0, 0.9, 21.1, 65.9 and 90.7%. The EC50 was 855 mg/L.


Description of key information

A study was performed to assess the effects of benzyl acetate on microorganisms. The method followed that described in the ISO 8192-1986 requirement E guideline (equivalent to OECD 209) (Muller, 1994). 
Nominal exposure concentrations were 180, 320, 560, 1000 and 1800 mg/L. Respiration rates were 33.0, 32.0, 25.5, 11.0 and 3.0 mg/L.h and the % inhibition values were 0, 0.9, 21.1, 65.9 and 90.7%. The EC50 was 855 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
855 mg/L

Additional information

A study was performed to assess the effects of benzyl acetate on microorganisms. The method followed that described in the ISO 8192-1986 requirement E guideline (equivalent to OECD 209). The EC50 value was 855 mg/L (Muller, 1994).