Alcohols, C10-16, ethoxylated, sulfates, mono(hydroxyethyl)ammonium salts

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05 May – 03 Jun 2022

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data based on the inhibition control of a ready biodegradability 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)

Version / remarks:

July 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 10.3 ml of the test item stock solution (20 g/L) and 5.15 ml of the reference substance (10 g/L) were added via pipette into the toxicity control vessel corresponding to a concentration of 40 mg/L organic carbon.

Test organisms (species):

activated sludge

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

21.0 – 22.7°C

Nominal and measured concentrations:

Nominal test substance concentration: 137 mg/L

Details on test conditions:

TEST CONDITIONS
- Composition of medium: mineral medium acc. to guideline
- Suspended solids concentration: 30 mg/L dry solids
- Continuous darkness: no (diffuse light)

TEST SYSTEM
- Culturing apparatus:
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: aerated by the passage of carbon dioxide-free air
- Measuring equipment: tIC measurement was performed with a total carbon analyser (TOC-L Shimadzu)
- Details of trap for CO2 and volatile organics if used: 200 mL 0.2 M NaOH

SAMPLING
- Sampling frequency: day 4, 7, 11, 14, 21 and 28
- Sampling method: NaOH was sampled from the CO2-absorber flasks

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 3 replicates
- Toxicity control: yes, 1 replicate

Reference substance (positive control):

yes

Remarks:

sodium benzoate

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 137 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other:

Remarks:

Result of toxicity control from ready biodegradability test

Details on results:

The mean CO2-evolution of the blank flasks was 24.9 mg/L on day 28.
A degradation of 90.5% within 14 days was determined in the toxicity control.

Results with reference substance (positive control):

The reference substance reached a degradation of 69.1% after 4 days (92.8% after 28 d)

Table 1: Mean degradation rates

	Day 0	Day 4	Day 7	Day 11	Day 14	Day 21	Day 28	Day 28 with IC reactor
Mean test substance	0	43.0	68.1	82.8	82.8	87.9	87.5	87.3
Mean reference substance	0	69.1	79.2	88.6	91.3	94.6	92.5	92.8
Toxicity control	0	52.3	74.3	787.8	90.5	92.8	95.0	94.7

Validity criteria fulfilled:

not specified

Description of key information

The assessment of the toxicity of the target substance to microorganisms is based on inhibition control of the available biodegradation screening study (OECD 301 B).

No inhibition of the activated sludge organisms was observed and a NOEC (14 d) of 137 mg/L (based on CO2 evolution of activated sludge organisms) was determined.

Additional information

The toxicity of the alkyl ether sulfates (AES) substances to microorganisms was assessed by read-across based on the grouping of substances (category approach). All data on toxicity to microorganisms available for the category were used to assess the toxicity of category substances to microorganisms. The available data indicate no adverse effects of alkyl ether sulfates on microbial activity. All substances of the alkyl ether sulfates category are considered readily biodegradable. In the available screening studies including 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 alkyl ether sulfates.