[No public or meaningful name is available]

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

key study

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)

Deviations:

yes

Remarks:

20 °C instead of 22 °C

Qualifier:

according to guideline

Guideline:

other: EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Deviations:

yes

Remarks:

20 °C instead of 22 °C

GLP compliance:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
Test substance was added directly to the test bottles.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source of inoculum/activated sludge: Collected from a municipal wastewater treatment plant in Usserød, Denmark.
- Laboratory culture: no
- Pretreatment: The activated sludge was stabilised under continuous aeration for a period of 2 d in order to reduce the content of easily degradable carbon.
- Concentration of sludge: 28.5 mg suspended solids (dry weight)/L

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Test temperature:

20°C

Details on test conditions:

TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 19.8 ± 0.0 °C
- pH: 7.6 (test start); 7.5 - 7.6 (test end)
- pH adjusted: no
- Suspended solids concentration: 28.5 mg/L (dw)

TEST SYSTEM
- Culturing apparatus: WTW OxiTop® Control System (770 mL test volume)
- Number of culture flasks/concentration: 4
- Measuring equipment: WTW OxiTop® Control System
- Test performed in closed vessels due to significant volatility of test substance: no

SAMPLING
- Sampling frequency: continuously
- Sampling method: The OxiTop® Control system automatically determines the oxygen consumption in the test bottles.
- Sterility check if applicable: no
- Sample storage before analysis: not applicable

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 4 bottles
- Abiotic sterile control: no
- Toxicity control: yes, 4 bottles (containing approx. 22 mg/L test item and 20 mg/L of the reference substance)
- Other: Reference substance: yes, 4 bottles

Reference substance (positive control):

yes

Remarks:

sodium benzoate

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

22 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):

The reference substance was degraded to 78 ± 2% of ThOD after 14 d and 85 ± 5% of ThOD after 28 d.

The toxicity control attained 70% degradation after 28 days of incubation.

Since more than 25% 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 22 mg/L can be used as NOEC value for the toxicity to aquatic microorganisms.

 

Reference 2

Endpoint:

toxicity to microorganisms, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to analogue justification document provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Result of toxicity control from ready biodegradability test

The toxicity control attained 70% degradation after 28 days of incubation.

Since more than 25% 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 22 mg/L can be used as NOEC value for the toxicity to aquatic microorganisms.

Description of key information

14-day NOEC (toxicity control) >= 22 mg/L (OECD 301 F); read-across

Additional information

Since no studies on the toxicity to aquatic microorganisms are available a ready biodegradability study is used to derive a NOEC for the toxicity to aquatic microorganisms. If a compound degrades well in a ready biodegradability test, or does not inhibit the degradation of a positive control at a certain concentration, this concentration can be used as a NOEC value. This approach is in accordance with the Guidance on information requirements and chemical safety assessment (Chapter R.7b: Endpoint specific guidance, ECHA 2017).

A substance can be assumed to be not inhibitory to aquatic microorganisms, if in the toxicity control of a ready biodegradation test, more than 25% degradation based on oxygen demand (BOD/ThOD) occurred within 14 days (OECD guideline 301). For the source substance Glycerides, C16-18 and C18-unsatd. mono- and di-, citrates a biodegradation test according to OECD guideline 301F is available. The test includes a toxicity control, which contains 22 mg/L of test substance and 20 mg/L of sodium benzoate. The toxicity control attained 81% degradation after 14 days of incubation. Hence, the substance is not toxic to aquatic microorganisms in the toxicity control and the test item concentration of 22 mg/L can be used as NOEC (NOEC (14 d) >= 22 mg/L).