Reaction product of 2,2'-oxydiethanol and 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate and hexan-6-olide and trimethylhexa-1,6-diyl diisocyanate

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:

10 Jan - 13 Feb 2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data based on the inhibition control of a ready biodegradability study. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2012).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge from the aeration tank of aomestic wastewater treatment plant, Rossdorf, Germany
- Storage conditions: aerobic
- Storage length: overnight
- Preparation of inoculum for exposure: The activated sludge used for this study was settled for 30 min before it was washed by centrifugation and the supernatant liquid phase decanted. The solid material was re-suspended in test water and centrifuged again. This procedure was performed three times. The sediment of the last washing was resuspended in test water and aerated overnight until use. An aliquot of this final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 3.5 g dry material per L (± 10%) were mixed with test water and then aerated until use. This suspension was used for the experiment.
- Concentration of sludge: 3.5 g/L on dry matter base
- Initial cell/biomass concentration: 28.7 mg sludge/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Details on test conditions:

TEST CONDITIONS
- Composition of medium: Reconstituted Test Water, prepared from analytical grade salts.
- Test temperature: 22 ± 1 °C
- pH: 7.6 (at the start of the test), 7.5 - 7.7 (at the end of the test)
- Suspended solids concentration: 28.7 mg sludge/L
- Continuous darkness: Yes.

TEST SYSTEM
- Culturing apparatus: BSB/BOD-Sensor-System, Aqualytic, Dortmund, Germany
- Number of culture flasks/concentration: 2
- Measuring equipment: BSB/BOD-Sensor-System, Aqualytic, Dortmund, Germany
- Test performed in open system: The test flasks were closed gas-tight by a measuring head.
- Details of trap for CO2 and volatile organics if used: A potassium hydroxide solution (45%) was used for trapping the produced carbon dioxide.

SAMPLING
- Sampling frequency: The change of pressure in the test flasks was measured by means of a manometric method each day. The temperature was recorded by means of the automated software AMR Wincontrol. pH-values were measured in procedure control, a separately prepared test flask with test item (to prevent loss of test item in the test flasks) and a separately prepared test flask without test item (control) at test start and in all flasks at the end of the test, except in the abiotic and toxicity control, using a pH-electrode WTW pH 340i.

Reference substance (positive control):

yes

Remarks:

benzoic acid, sodium salt

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

101.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Result of toxicity control from ready biodegradability test

Results with reference substance (positive control):

In the toxicity control containing both, the test item and the reference item sodium benzoate, 37% (ThODNH4) biodegradation was noted within 14 days and 41% (ThODNH4) biodegradation after 28 days of incubation (35% and 39% based on ThODNO3). According to the test guidelines, the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms because degradation was >25% within 14 days.

The toxicity control attained 37% degradation after 14 days of incubation.

 

“If in  a toxicity test, containing both the test and reference substance, less than 35% degradation (based on total DOC) or less than 25% (based on total ThOD or ThCO2) occurred within 14 days, the test substance can be assumed to be inhibitory.” (OECD guideline 301)

Since more than 35% degradation occurred in the toxicity control, the substance is with high probability not toxic to aquatic microorganisms. The test item concentration in the toxicity control of 101.8 mg test item/L can be used as NOEC value for the toxicity to aquatic microorganisms.

Description of key information

NOEC (14 d) ≥ 101.8 mg/L (nominal, OECD 301)

Additional information

The microbial toxicity of the substance was inferred from the toxicity control of a standard ready biodegradability test conducted according to OECD 301 F and GLP, as recommended by the Guidance document “Chapter R.7b Endpoint specific Guidance on Information Requirements and Chemical Safety Assessment” (ECHA, 2017) in absence of a microbial toxicity test according to OECD 209.

In the manometric respirometry test, the toxicity control was prepared by inoculating 101.8 mg test item and 101.2 mg/L of the reference compound stock solution (sodium benzoate), with activated sludge (3.5 g/L on dry matter base) under aerobic conditions in diffuse light for 34 d.The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

In the toxicity control containing both, the test item and the reference item sodium benzoate, 37% (ThODNH4) biodegradation was noted within 14 days and 41% (ThODNH4) biodegradation after 28 days of incubation (35% and 39% based on ThODNO3).After 14 d, degradation of the reference compound and test item in the toxicity control was 37%(ThODNH4)and thus above the criterion (< 25% degradation in 14 d) for inhibition effects to the inoculum. Based on this result, the test item had no toxic effect on the inoculumand a NOEC (14 d) of ≥ 101.8 mg/L was derivedaccording to the Guidance document “Chapter R.7b Endpoint specific Guidance on Information Requirements and Chemical Safety Assessment” (ECHA, 2017).