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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
other: ASTM´s "Microbiological Inhibtion Testing Procedure"
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): 2-hydroxethyl acrylate
- Physical state: liquid
- Analytical purity: 97%
- Storage condition of test material: cool, dark
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Test substance: A stock solution of the test substance was prepared at 1000 mg active/L in deionized (DI) water. An aliquot of the stock solution was submitted for total organic carbon (TOC) analysis. The result was 0.553 mg C/mg active.
- Reference substance: A stock solution was prepared in DI water at a concentration of 300 mg active/L. An aliquot was submitted for TOC analysis. The result was 0.4 mg C/mg active.
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Source: Downington Regional Water Pollution Control Center in Downington, Pennsylvania
- Preparation of inoculum for exposure: The total suspended solids was determined to be 3247 mg/L. Sludge was added to to semi-continuous activated sludge and diluted with tap water to obtain a concentration of 2500 mg/L. Sludge was aerated overnight prior test. 40 mL of this sludge was diluted 1:10 with BOD dilution water. The diluted sludge was used as the microbial inoculum.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
20 ± 0.2 °C
Dissolved oxygen:
ca. 9 mg/L at test initiation
Nominal and measured concentrations:
- Nominal test concentrations: 0 (control), 0.1, 1.0, 5.0, 10, 15, 20, 100, 300, 500 and 800 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 300 mL glass bottles
- Fill volume: 100 mL test solution
- Aeration: yes
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: BOD dilution water; 1 liter of ASTM Type II (deionized) water contains 1 mL of following standard reagent solutions: magnesium sulfate solution, 2.25%; calcium chloride solution, 2.75%; phosphate buffer, pH 7.2; ferric chloride solution, 0.025%
Reference substance (positive control):
yes
Remarks:
D-glucose (6 mg/L)
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate

Test results for dilution water and D-glucose controls:

Dilution water controls

D-glucose controls

Bottle no.

Initial DO (mg O2/L)

Final DO (mg O2/L)

Bottle no.

Initial DO (mg O2/L)

Final DO (mg O2/L)

46

9.0

9.0

55

9.1

5.6

58

9.2

9.1

209

9.1

5.6

Description of key information

The 72-h EC10 value is >100 mg/L as observed in a Microbiological Inhibition Test.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
100 mg/L

Additional information

The toxicity of 2-hydroxyethyl acrylate to microorganisms of a domestic sewage treatment plant was investigated according to ASTM´s "Microbiological Inhibition Testing Procedure" (Roy F. Weston, Inc., 1996). Activated sludge was incubated with nominal test substance concentrations of 0 (control), 0.1, 1.0, 5.0, 10, 15, 20, 100, 300, 500 and 800 mg/L. After 72 hours of exposure an EC10 > 100 mg/L was determined measuring the respiration rate.