[No public or meaningful name is available]

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Remarks:

Study was a toxicity control conducted as part of a CO2 evolution test in accordance with OECD Guideline 301B.

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14 November 2017 to 15 January 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: According to OECD 301B and EU C.4-C Toxicity test performed as part of a ready biodegradability CO2 evolution test performed according to OECD 301B and EU C.4-C

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

The test substance is listed as ATHC. The test substance is a pale yellow slightly viscous liquid. The test substance was obtained from the Sponsor, Vertellus Holdings LLC and stored at room temperature in the dark.

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

A mixed population of activated sewage sludge micro-organisms was obtained on 13 November 2017 from the aeration stage of the Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, which treats predominantly domestic sewage.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Details on test conditions:

A toxicity control, containing the test item and sodium benzoate was prepared to assess any toxic effect of the test item on the sewage sludge micro-organisms used in the test. An amount of the test item (46.8 mg) was dispersed directly in mineral medium prior to dispersal in inoculated mineral medium with the aid of high shear mixing. An aliquot (51.4 mL) of the sodium benzoate stock solution was added to the test vessel and the volume was adjusted to 3 liters to give a final concentration of 15.6 mg/L test item plus 17.1 mg sodium benzoate/L, equivalent to a total of 20 mg carbon/L.

Key result

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

15.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other:

Remarks:

inhibition of CO2 evolution

At a test substance concentration of 15.6 mg/L and a reference substance concentration of 17.1 mg sodium benzoate/L, the toxicity control attained 49% degradation after 14 days and 45% degradation after 28 days and 61% after 60 days, thereby confirming that the test substance did not exhibit an inhibitory effect on the sewage treatment micro-organisms used in the test (i.e., test substance and reference substance attained ≥ 25% degradation by Day 14 for the test substance to be considered as non-inhibitory).  The slight decrease in biodegradation between Days 14 and 28 was considered to be due to sampling/analytical variation.

Validity criteria fulfilled:

yes

Remarks:

IC content <5% (protocol ≤ 5%); CO2 emitted by controls 33.52 mg/L (protocol <70 mg/L; diff.reps less than 20% (protocol ≤20 %); degradation positive control 80% at 14 d (protocol greater than 60% ≤14 d); degradation toxicity d 14, 49% (protocol ≥25%).

Conclusions:

The test substance is considered as not toxic towards the inoculum at a concentration of 15.6 mg/L. Degradation in the toxicity flask was 49% after 14 days. The guideline indicates that the test item can be considered as toxic towards the inoculum if degradation in the toxicity flask is below 25% after 14 days.

Description of key information

The key study was a toxicity control conducted as part of a CO₂ evolution test in accordance with OECD Guideline 301B. The test substance was shown to be non-inhibitory toward the inoculum at a concentration of 15.6 mg/L. Degradation in the toxicity flask was 49% after 14 days.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

15.6 mg/L