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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Remarks:
Biodegradation in water: screening test, toxicity control is used to derive effect concentration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-03-09 to 2017-05-10
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
other: EU method C.4-D
Version / remarks:
2008
Deviations:
no
Qualifier:
according to
Guideline:
other: OECD Guideline 301F (Ready Biodegradability: Manometric Respiratory Test)
Version / remarks:
1992
Deviations:
no
Principles of method if other than guideline:
From biodegradation in water: screening test, toxicity control is used to derive effect concentration
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method:The concentration in the test assays were 100 mg per liter mineral test medium (25 mg/250 mL, test suspension A) and 48 mg per liter mineral test medium (12 mg/250 mL, test suspension B), respectively. 100 mg and 48 mg test item correspond to 123 mg and 59 mg ThOD, respectively.
Test organisms (species):
activated sludge, domestic
Details on inoculum:
Fresh samples of activated sludge are withdrawn on March 09th, 2017 from the sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany, which is mainly fed with municipal wastewater. Since it was not necessary, the samples were not washed with mineral medium after the arrival at the laboratory but kept aerobic until use. The concentration was adjusted to 3.2 g/L and verified by dry mass measurement. The concentration used in the test was 29.6 mg dry mass/liter (7.4 mg dry mass/250 mL).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
28 d
Test temperature:
22°C ± 1°C
pH:
7.4 ± 0.2
Nominal and measured concentrations:
Nominal concentrations of the test item 100 mg/L and 48 mg/L, reference item (sodium benzoate) 100 mg/L
Details on test conditions:
- Composition of medium:
( a )
KH2PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 26.64 g/L
NH4Cl 0.50 g/L
pH 7.4 ± 0.2
( b )
CaCl2 x 2 H2O 36.40 g/L
( c )
MgSO4 x 7 H2O 22.50 g/L
( d )
FeCl3 x 6 H2O 0.25 g/L.
The mineral medium applied in the test contained 10 mL/L of mineral stock solution a and 1 mL/L of the mineral stock solution b–d, respectively.

TEST SYSTEM
- Test vessel: 500 mL glass vessels
- Material, size, headspace, fill volume: 500 mL glass vessels at a medium volume of 250 mL
- No. of vessels per concentration (replicates): 2 vessels containing test item (100 mg/L) and inoculum; 2 vessels containing test item (48 mg/L) and inoculum; 2 vessels containing only inoculum; 2 vessels containing reference item (100 mg/L) and inoculum, 2 vessels containing test item (100 mg/L), reference item (100 mg/L) and inoculum.
- No. of vessels per control (replicates): 2
- Sludge concentration (weight of dry solids per volume): 29.6 mg dry mass/L
- Method used to create aerobic conditions: The medium was aerated during the whole test.
- Measuring equipment: SAPROMAT respirometer (VOITH Inc.).

SAMPLING
- Sampling frequency: The measurement and recording of the oxygen demand was carried out continuously

CONTROL AND BLANK SYSTEM
- Inoculum blank: The blank control consists of inoculated mineral medium only
- Toxicity control: A toxicity control containing test item at 100 mg per litre and reference item at 100 mg per litre mineral test medium was applied.

OTHER TEST CONDITIONS
- Photoperiod: continuous darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : O2 consumption
TEST CONCENTRATIONS
- Test concentrations: 100 and 48 mg/L

STATISTIC METHODS:
Theoretical Oxygen Demand (ThOD):
The Theoretical Oxygen Demand (ThOD) was calculated on the basis of the sum formula of the test and reference item by:
ThOD [g/g] = 16 * (2C + 1/2H + 1/2Na – O) / Molecular weight.
The ThOD values for Na-benzoate, the test item and the toxicity control were determined as follows:
ThOD test item : 1.229 mg O2 /mg test item
ThOD Na-Benzoate : 1.665 mg O2 /mg reference item
ThOD toxicity control : 1.447 mg O2 /mg substance mixture

Biochemical Oxygen Demand (BOD):
The Biochemical Oxygen Demand (BOD) was calculated on the basis of the test raw data by BOD [mg/mg] = mg O2 uptake corrected by blank per mg test item.
The percent degradation was calculated according to the following formula:
Dt = [(Ct –Cb ) / ThOD] x 100

Dt : degradation (%) at time t;
Ct : mean oxygen consumption (mg/L) in the test suspension at time t;
Cb : mean oxygen consumption (mg/L) in the blanks at time t;
ThOD: Theoretical oxygen demand of the test suspension (mg/L).
Reference substance (positive control):
no
Key result
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks on result:
other:
Remarks:
comparison of procedural and toxicity control
Details on results:
The biodegradation of the item mixture in the toxicity control was found to be 71.3 % after 14 days of incubation. Thus, according to the test guidelines, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L, as the biodegradation in the toxicity control was higher than 25% within 14 days of incubation.
Validity criteria fulfilled:
yes
Remarks:
Validity criteria as outlined under "any other information on material and methods" were fulfiled.
Conclusions:
The toxicity of alpha methyl glucoside to microorganisms was investigated during a ready biodegradation study. The test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L.
Executive summary:

The toxicity of alpha methyl glucoside to microorganisms was investigated during a ready biodegradation study according to EU Method C.4-D (2008) and OECD guideline 301 F (1992), Manometric Respirometry Test over a period of 28 days and using an inoculum obtained from activated sludge from a predominantly domestic sewage treatment plant.

Inoculum blank, procedural/functional control with the reference substance Sodium benzoate and a toxicity control with 100 mg/L test item and 100 mg/L reference item Sodium benzoate were performed.

The reference item degraded normally (85.0 % by within 14 days). By the end of the test, the reference item was degraded to an average of 88.3%.

The biodegradation of the item mixture in the toxicity control was found to be 71.3 % after 14 days of incubation. Thus, according to the test guidelines, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L, as the biodegradation in the toxicity control was higher than 25% within 14 days of incubation.

Description of key information

- Results from a Biodegradation in water: screening test, GLP, RL1, no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L

Key value for chemical safety assessment

Additional information

The toxicity of alpha methyl glucoside to microorganisms was investigated during a ready biodegradation study according to EU Method C.4-D (2008) and OECD guideline 301 F (1992), Manometric Respirometry Test over a period of 28 days and using an inoculum obtained from activated sludge from a predominantly domestic sewage treatment plant.

Inoculum blank, procedural/functional control with the reference substance Sodium benzoate and a toxicity control with 100 mg/L test item and 100 mg/L reference item Sodium benzoate were performed.

The reference item degraded normally (85.0 % by within 14 days). By the end of the test, the reference item was degraded to an average of 88.3%.

The biodegradation of the item mixture in the toxicity control was found to be 71.3 % after 14 days of incubation. Thus, according to the test guidelines, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L, as the biodegradation in the toxicity control was higher than 25% within 14 days of incubation.