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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:
yes (incl. certificate)
Vehicle:
no
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): secondary effluent are withdrawn on November 29th, 2017 from the sewage treatment plant
Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany, which is mainly fed with municipal wastewater

The samples were kept aerobic during transport to the laboratory. The samples were allowed to settle for 1 hour and filtered through a coarse filter paper. The inoculum was kept aerobic until required.
The concentration used in the test was 1 mL/L.
Test type:
static
Water media type:
freshwater
Total exposure duration:
28 d
Test temperature:
20°C
pH:
7.4 ± 0.2
Nominal and measured concentrations:
5 mg/L
Details on test conditions:
TEST SYSTEM
- Culturing apparatus: 300 mL test vessels
- Number of culture flasks/concentration: 16
- Method used to create aerobic conditions: strongly aerated for 20 minutes and allowed to stand for 20 h at test temperature
- Measuring equipment: O2 electrode

SAMPLING
- Sampling frequency: test start and at day 2, 5, 7, 9, 14, 21, and 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: The blank control consisted of inoculated mineral medium only, 16 vessels
- Abiotic sterile control: no
- Toxicity control: A toxicity control containing test item at 5 mg per litre and reference item at 2 mg per litre mineral test medium was applied, 8 vessels
- Procedural control: 16 vessels containing reference item (5 mg/L) and inoculum
Reference substance (positive control):
no
Duration:
14 d
Dose descriptor:
IC10
Effect conc.:
5 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Details on results:
The biodegradation of the test item after 28 days of incubation in the static test was found to be 0 % in the assays with 2 mg/L and 5 mg/L. Thus, no biodegradation within a 10-day-window could be obtained.
The biodegradation of the item mixture in the toxicity control was found to be 28 % after 14 days of incubation. Thus, the demanded threshold value of 25 % is exceeded and the test item can be identified as non-toxic in a ready biodegradability test.
Conclusions:
The threshold value of 25 % is exceeded and the test item can be identified as non-toxic in a ready biodegradability test.
Executive summary:

The biodegradation of Reaction product of lauryl-PDA/lauryl-DETA with chloroacetic acid was investigated over a 28-day period in a Closed Bottle Test according to OECD guideline 301 D and EU method C.4-E. The test medium was inoculated with microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater.

The test solutions were incubated in closed flasks at 20 °C ± 1 °C for 28 days. The rate of degradation was monitored by measuring the decrease of oxygen in the medium over a 28-d period. The amount of oxygen taken up by the microbial population during biodegradation of the test item at a concentration of 2 mg/L (ThOD = 1.44 mg/L) and 5 mg/L (ThOD = 3.60 mg/L), respectively, corrected for uptake by the blank inoculum run in parallel, was expressed as a percentage of the ThOD (theoretical oxygen demand). In order to check the procedure, sodium benzoate was used as a degradable reference item at a concentration of 2 mg/L, along with a toxicity control at 5 mg/Ltest itemand 2 mg/L sodium benzoate.

The biodegradation of Reaction product of lauryl-PDA/lauryl-DETA with chloroacetic acid in the static test was found to be 0 % for a concentration of 2 mg test item per liter and 5 mg test item per liter after 28 days.Thus, no biodegradation within a 10-day-window could be obtained.

The degradation of the reference substance sodium benzoate had reached 72 % within the first 14 days.

The difference of extremes of replicate values of the removal of the test item at the end of the test is less than 20%. Therefore, the test can be considered as valid.

No inhibitory effects of the test item were observed (more than 25 % degradation occurred within 14 days) in the toxicity control.

Therefore, Reaction product of lauryl-PDA/lauryl-DETA with chloroacetic acid must be considered as not readily biodegradable under the chosen test conditions.

Description of key information

14 d IC10 >/= 5 mg/L (OECD TG 301D, RL1, GLP)

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
5 mg/L

Additional information

The biodegradation of Reaction product of lauryl-PDA/lauryl-DETA with chloroacetic acid was investigated over a 28-day period in a Closed Bottle Test according to OECD guideline 301 D and EU method C.4-E. The test medium was inoculated with microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater.

The test solutions were incubated in closed flasks at 20 °C ± 1 °C for 28 days. The rate of degradation was monitored by measuring the decrease of oxygen in the medium over a 28-d period. The amount of oxygen taken up by the microbial population during biodegradation of the test item at a concentration of 2 mg/L (ThOD = 1.44 mg/L) and 5 mg/L (ThOD = 3.60 mg/L), respectively, corrected for uptake by the blank inoculum run in parallel, was expressed as a percentage of the ThOD (theoretical oxygen demand). In order to check the procedure, sodium benzoate was used as a degradable reference item at a concentration of 2 mg/L, along with a toxicity control at 5 mg/Ltest itemand 2 mg/L sodium benzoate.

The biodegradation of Reaction product of lauryl-PDA/lauryl-DETA with chloroacetic acid in the static test was found to be 0 % for a concentration of 2 mg test item per liter and 5 mg test item per liter after 28 days.Thus, no biodegradation within a 10-day-window could be obtained.

The degradation of the reference substance sodium benzoate had reached 72 % within the first 14 days.

The difference of extremes of replicate values of the removal of the test item at the end of the test is less than 20%. Therefore, the test can be considered as valid.

No inhibitory effects of the test item were observed (more than 25 % degradation occurred within 14 days) in the toxicity control.

Therefore, Reaction product of lauryl-PDA/lauryl-DETA with chloroacetic acid must be considered as not readily biodegradable under the chosen test conditions.