Sodium 2-heptyl-2,3-dihydro-3-(2-hydroxyethyl)-1H-imidazole-1-propionate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 days

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test substance name: Crodateric CYAP
Scymaris reference number: 1014TS047
Supplier: Croda Europe Ltd.
Lot/batch number: PS-196-555
Purity/strength: 98.15% w/w solids

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Activated sludge was obtained from Totnes Sewage Treatment Works, Totnes, Devon, UK on 07 September 2017. This works treats sewage of predominantly domestic origin. At the laboratory, the activated sludge was kept aerated at room temperature and the pH maintained at 7.0  1.0.

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Remarks:

Test material is 98.15% active ingredient

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

All test bottles contained the prepared activated sludge inoculum in mineral medium, as described in Section 3.4. Following the pre-conditioning the test bottles were set up for the test according to the experimental design shown in Table 1. Inoculum blanks contained no test or reference substance, in order to demonstrate there was no other carbon source in the medium. Positive controls contained the reference substance, sodium benzoate at 100 mg/L, to demonstrate the viability of the inoculum. The test substance bottles contained Crodateric CYAP at 100 mg/L, to determine the biodegradation of the test substance. Toxicity controls contained the test and reference substances, both at 100 mg/L, and were used to show if there had been any inhibition of the inoculum by the test substance. Each set of bottles was prepared in triplicate. Additional single replicate Crodateric CYAP and toxicity control bottles were prepared for determination of pH at day 0, so undissolved test substance was not removed by the pH probe.
Due to the aqueous solubility being unknown, the bottles containing Crodateric CYAP were prepared by directly weighing the required quantity to the relevant test bottles. Sodium benzoate was dosed as a 1000 mg/L stock solution, prepared by dissolving sodium benzoate in RO water to give a clear and colourless solution, this was prepared on the day of exposure start.
Oxygen uptake was recorded automatically every 240 minutes during the 28-day experimental period. Oxygen uptake values were corrected for the inoculum blank and the biodegradation was calculated as a percentage of the chemical oxygen demand for the substance under test and as a percentage of the theoretical oxygen demand for the reference substance

Reference substance:

benzoic acid, sodium salt

Test performance:

The validity requirements of the OECD guideline state:
• the difference between extremes of replicate biodegradation values should be less than 20% at the end of 10-day window, at the plateau or at the end of the test;
• the positive control should achieve > 60% biodegradation by Day 14.
• the oxygen consumption of the inoculum blank should not exceed 60 mg/L in 28 days.
Mean oxygen uptake of the inoculum blank was below 60 mg/L, as required in the OECD guideline.
The difference between replicate Crodateric CYAP extremes was < 20% after the 10-day window, at plateau, and on day 28. Sodium benzoate reached a mean 68% biodegradation by Day 14. The mean oxygen consumed in the inoculum blanks was 12.4 mg/L after 28 days. Therefore, this test has satisfied all the validity criteria

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 67

St. dev.:

4

Sampling time:

28 d

Details on results:

The COD of the test substance was measured as 1.66 g O2/g and the mean BOD value after 28 days was 1.1 g O2/g.
The percentage degradation was calculated as (BOD/COD) x 100

Key result

Parameter:

COD

Value:

1.66 g O2/g test mat.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Crodateric CYAP attained a mean level of biodegradation (based on the BOD:COD ratio) of 67% after 28 days and the results showed good replication.
As Crodateric CYAP is UVCB, according to OECD and ECHA guidance documents, the 10-day window can be waived. Therefore, as > 60% biodegradation was achieved within 28 days Crodateric CYAP is readily biodegradable.

Description of key information

Crodateric CYAP attained a mean level of biodegradation (based on the BOD:COD ratio) of 67% after 28 days and the results showed good replication.  

As Crodateric CYAP is UVCB, according to OECD and ECHA guidance documents, the 10-day window can be waived.  Therefore, as > 60% biodegradation was achieved within 28 days Crodateric CYAP is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable