Isooctadecyl pivalate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms

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 2014).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

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

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)
- The concentration in the test assays were 20 mg per litre mineral test medium (5 mg/250 mL) and 100 mg per litre mineral test medium (25 mg/250 mL), respectively. 20 mg test item correspond to 60.5 mg ThOD. 100 mg test item correspond to 302.3 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 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.

Test organisms (species):

activated sludge of a predominantly domestic sewage

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: 29th July 2015
- 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

Test temperature:

22 °C ± 1°C

pH:

7.8

Nominal and measured concentrations:

nominal: 100 mg/L

Details on test conditions:

Principle: Electro-chemical analysis process. The biodegradation process consumes the dissolved oxygen in the test medium and generates CO2. The CO2 is absorbed by soda lime, which results in a decrease of the total pressure in the airtight test flasks. The pressure drop results in closing a current circuit. For sample size, flow duration and current intensity, the control unit calculates the BOD of the sample under investigation. By coupling the measurement unit to a PC, a continuous recording of oxygen consumption (mg O2) is possible. The consumed oxygen is replaced by electrolytically generated oxygen from a copper sulfate solution.
Incubated under continuous stirring in SAPROMAT respirometer (VOITH Inc.). Oxygen consumption was measured and recorded
continuously throughout the duration of the test.

Reference substance (positive control):

yes

Remarks:

sodium benzoate

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 100 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 item was degraded by an average of 89 % by Exposure Day 14, thus confirming suitability of the activated sludge. At the end of the test (Day 28), the reference item was degraded by an average of 94 %.

The toxicity control attained 36.6% (SD 2.4%) 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 36.6% 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

NOEC (14 d) ≥ 100 mg/L (OECD 301F, toxicity control)

Additional information

The toxicity of Isooctadecyl pivalate (CAS 58958-60-4) to activated sludge microorganisms microorganisms was investigated in a biodegradation study according to OECD 301F under GLP conditions. The toxicity control available in this test contained activated sludge of a predominantly domestic sewage, reference substance (sodium benzoate) and the test substance at a concentration of 100 mg/L. The toxicity control attained 36.6% degradation after 14 d of incubation. Since more than 25% degradation was observed 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. Thus a NOEC (14 d) of ≥ 100 mg/L resulted.