Glycerides, C18-36

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

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)

GLP compliance:

yes (incl. QA statement)

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- The concentration in the test assays were 100 and 20 mg per litre mineral test medium (25 and 5 mg/250 mL), respectively. 100 mg test item correspond to 301.6 mg ThOD. 20 mg test item correspond to 60.3 mg ThOD. The required amount of test item was added directly on a weight basis via Teflon discs. Subsequently, the required volume of aqueous reference stock solution (if applicable) and mineral medium were added to the vessels.
- The concentration in the test vessels with reference item (procedural control, toxicity control) was 100 mg per litre mineral test medium (25 mg/250 mL).
- A further solution containing both test and reference item at the same concentrations as in the individual
solutions (test item 100 mg/L, reference item 100 mg/L) was prepared to determine the possible toxicity of the test item against the inoculum.
- Further flasks with mineral medium only were prepared for inoculum controls.
- Abiotic controls were also prepared to measure any possible abiotic degradation; a solution of the test item at about 100 mg/L was sterilized by the addition of 1 mL/L HgCl2 (10 g/L).
- In all test assays except of the abiotic controls, 2.47 mL of the inoculum stock solution were transferred for inoculation (per 250 mL) resulting in a concentration of 29.6 mg dry mass/litre (7.4 mg dry mass/250 mL).

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): sewage treatment plant Ruhrverband Kläranlage, Sunthelle 6, 57392 Schmallenberg, Germany
- Date of sampling: 10th August 2016
- Storage conditions: No storage
- Preparation of inoculum for exposure: No washing, the concentration was adjusted to 3.0 g/L and verified by dry mass measurement.
- Pretreatment: Kept aerobic until use
- Concentration of sludge in the test: 29.6 mg dry mass/litre

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

14 d

Details on test conditions:

TEST SYSTEM
- Aeration: The suspension was aerated during the whole test.
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per abiotic control (replicates): 2
- Sludge concentration (weight of dry solids per volume): 29.6 mg dry mass/litre
- other: The solutions were stirred during the whole test duration.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water

OTHER TEST CONDITIONS
- Adjustment of pH: Before test start the pH values of all solutions are determined and adjusted on 7.4 ± 0.2 with H2SO4 (50 g/L).
- Photoperiod: The test was run in darkness.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The measurement and recording of the oxygen demand was carried out continuously (daily). Twice a week the correct incubation temperature of the water bath and an adequate stirring were checked. At the end of the test the pH values of all solutions were determined.

Reference substance (positive control):

yes

Remarks:

benzoic acid, sodium salt

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Results of toxicity control from ready biodegradability test

Results with reference substance (positive control):

The reference material (sodium benzoate) attained 86% within the first 14 days in the absence of the test item.

The toxicity control attained 31.8% 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 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 100 mg/L can be used as NOEC value for the toxicity to aquatic microorganisms.

Description of key information

The substance is not toxic to aquatic microorganisms in the toxicity control.

Additional information

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) or CO2 evolution (CO2/ThCO2)] occurred within 14 days (OECD guideline 301). For the test substance a biodegradation test according to OECD guideline 301F is available. The test includes a toxicity control, which contains 100 mg/L and 100 mg/L of the reference material [sodium benzoate]. The toxicity control attained 31.8% 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 100 mg/L can be used as NOEC.