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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Remarks:
toxicity control from biodegradation in water screening test is used to derive effect concentration
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2004-12-02 to 2004-12-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
reference to same study
Qualifier:
according to guideline
Guideline:
other: OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test) (adopted July 17, 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. QA statement)
Analytical monitoring:
no
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): Municipal sewage treatment plant, D-31137 Hildesheim
- Pretreatment: The activated sludge was maintained in an aerobic condition by aeration for four hours and then homogenized with a mixer. The sludge was filtered and the filtrate (30 mL) was subsequently used to initiate inoculation.
- Concentration of sludge: 1E07-1E08 CFU/L in inoculum; 1E05-1E06 CFU/L in test vessels
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
28 d
Test temperature:
20 - 24°C
pH:
7.56 - 7.59 (test item), 7.51 - 7.59 (control), 7.86 (functional control), 7.83 (toxicity control)
Nominal and measured concentrations:
45 mg/L (11.8 mg C/L), nominal
Details on test conditions:
TEST CONDITIONS
- Composition of medium: Mineral nutrient solution acc. to OECD 301 B/CO2 Evolution Test
- Additional substrate: no
- Test temperature: 20 - 24°C, continuously stirred
- pH: 7.56 - 7.59 (test item), 7.51 - 7.59 (control), 7.86 (functional control), 7.83 (toxicity control)
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 5000 mL, brown glass; fill volume 3000 mL
- Number of culture flasks/concentration: dupilcate (test item)
- Method used to create aerobic conditions: The vessels were connected to the system for the production of CO2 free air and aerated for 24 h.
- Details of trap for CO2 and volatile organics if used: The CO2 adsorption vessels were connected to the air outlets of the incubation vessels via a series of 3 gas wash bottles.

SAMPLING
- Sampling frequency: three times a week during the first ten days and thereafter twice weekly + on day 29

CONTROL AND BLANK SYSTEM
- Inoculum blank: Nutrient solution and inoculum, duplicates
- functional control: Sodium acetate, 35 mg/L (10.2 mg C/L), single replicate
- Toxicity control: Sodium acetate, 35 mg/L (10.2 mg C/L) + test item 45 mg/L (11.8 mg C/L), single replicate
Reference substance (positive control):
no
Key result
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
45 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: comparison of procedural and toxicity control
Details on results:
The biodegradation of the item mixture in the toxicity control was found to be 63 % after 14 days of incubation and came to a maximum of 85 % after 28 days. Thus, according to the test guidelines, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 45 mg/L, as the biodegradation in the toxicity control was higher than 35% within 14 days of incubation.

Validity criteria fulfilled:
yes
Conclusions:
The toxicity of C8-10 Alkylamidopropyl betaine 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 45 mg/L.
Executive summary:

The toxicity of C8-10 Alkylamidopropyl betaine (35% a.i.) to microorganisms was investigated during a ready biodegradation study (CO2 Evolution Test) according to OECD guideline 301 B (1992) 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 acetate and a toxicity control with 45 mg/L test item and 35 mg/L reference item Sodium acetate were performed.

The reference item degraded normally (68% within 14 days). By the end of the test, the reference item was degraded by 82%.

The biodegradation of the item mixture in the toxicity control was found to be 63% 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 45 mg/L, as the biodegradation in the toxicity control was higher than 35% within 14 days of incubation.

Description of key information

14 d NOEC > 45 mg a.i./L, OECD TG 301 B, GLP, RL1

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
45 mg/L

Additional information

The toxicity of C8-10 Alkylamidopropyl betaine (35% a.i.) to microorganisms was investigated during a ready biodegradation study (CO2 Evolution Test) according to OECD guideline 301 B (1992) 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 acetate and a toxicity control with 45 mg/L test item and 35 mg/L reference item Sodium acetate were performed.

The reference item degraded normally (68% within 14 days). By the end of the test, the reference item was degraded by 82%.

The biodegradation of the item mixture in the toxicity control was found to be 63% 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 45 mg/L, as the biodegradation in the toxicity control was higher than 35% within 14 days of incubation.