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Diss Factsheets

Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Test 1: 19 - 20 OCT 1993; Test 2: 21 - 22 OCT 1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
no guideline followed
Principles of method if other than guideline:
Oxygen consumption test according to a method developed by Hüls AG
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Pseudomonas putida
Details on inoculum:
- Laboratory culture: in-house culture originally obtained from "Institut für Wasser-, Boden- und Lufthygiene des BGA (Berlin)"
- Preparation of inoculum for exposure: 200 mL steril medium was inoculated with 80 mL bacteria suspension (liquid culture of test organism, approximately 19 h incubation time, bacterial count approximately 10 x 10 exp. 5 bacteria/mL - extinction 436 nm: 0.29 - 0.31). Inoculum was aerated and stirred for 5 min.
- Initial biomass concentration: bacterial count approximately 10 x 10 exp. 5 bacteria/mL
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
5.33 h
Remarks on exposure duration:
1st test: 5.33 h; 2nd test: 5.5 h
Test temperature:
pre-culture:
Test 1: 24.8 - 25.0 °C
Test 2: 24.9 - 25.0 °C

incubation period:
test 1: 24.7 - 26.6 °C
test 2: 24.7 - 26.0 °C
Nominal and measured concentrations:
Nominal test concentrations: 100, 500, 1000 and 2000 µg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 mL BSB-bottles
- Type (delete if not applicable): closed
- No. of organisms per vessel: 10 x 10 exp. 5 bacterial count
- No. of vessels per concentration (replicates): 4 (in two of them 1 mL HgCl3 was added for determination of the degree of autoxidation)
- No. of vessels per control (replicates): 5


Reference substance (positive control):
no
Duration:
5 h
Dose descriptor:
EC50
Effect conc.:
> 2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate

No dose-response relationship of the test results, thus no EC10 available

Test

Concentration [µg/L]

100

500

1000

2000

1

11.1%

7.3%

5.5%

2.6%

2

11.0%

9.6%

5.1%

4.5%

Validity criteria fulfilled:
not specified

Description of key information

 The assessment of the toxicity of the target substance to microorganisms is based on the results of a GLP study investigating the inhibition of respiration rate of Pseudomonas putida. There was no clear dose-response up to the highest test concentration of 2 mg/L. Thus an EC50 (5 h) >2 mg/L (nominal) is used as key value for the CSA of the target substance. 

Key value for chemical safety assessment

Additional information

The toxicity of the Ethoxylates (AE) category substances to microorganisms was assessed by read-across based on the grouping of substances (category approach). The available data were used for a general assessment of the toxicity of the Alcohol Ethoxylates (AE) category substances to microorganisms. Based on the available data adverse effects on microbial activity are not expected. The substances of the Alcohol Ethoxylates (AE) category are readily biodegradable. In all studies conducted with a toxicity control, no inhibition of the degradation process by the test substance was observed. The available studies investigating the respiration inhibition of activated sludge organisms and Pseudomonas putida determined no detrimental effects of the tested Alcohol Ethoxylates.