Alcohols, C18-22, distn. residues

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant AZV Breisgauer Bucht was used as inoculum with a concentration corresponding to 30 mg dry solids per litre. The treatment plant
clarifies predominantly domestic wastewater and has a capacity of 600,000 inhabitant equivalents. Sampling date of activated sludge was 19 September 2018. The dry solid content of the activated sludge was 4.8 g/L. It was determined by weight measurements after drying at 105°C for 5 hours (mean of triplicate measurements). The activated sludge was washed twice with tap water by settling the sludge, decanting the supernatant and re-suspending the sludge.

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Mineral medium
A: Potassium dihydrogenphosphate KH2PO4 8.50 g; Dipotassium hydrogenphosphate K2HPO4 21.75 g; Disodium hydrogenphosphate dihydrate Na2HPO4 * 2 H2O 33.40 g; Ammonium chloride NH4Cl 0.50 g are dissolved in demineralised water and made up to 1 litre. The pH of the solution should be 7.4.
B: Calcium chloride dihydrate CaCl2 * 2H2O 36.4 g is dissolved in demineralised water and made up to 1 litre.
C: Magnesium sulfate heptahydrate MgSO4 * 7H2O 22.5 g is dissolved in demineralised water and made up to 1 litre.
D: Iron (III) chloride hexahydrate FeCl3 * 6H2O 0.25 g is dissolved in demineralised water, stabilised with one drop of concentrated HCl and made up to 1 litre.
For preparation of the mineral medium 10 mL of solution (A) is mixed with 900 mL demineralised water, 1 mL each of solutions (B), (C) and (D) are added and the volume is made up to 1 litre.
- Test temperature: 20.0 – 21.7°C
- Aeration of dilution water: yes

TEST SYSTEM
- Culturing apparatus: 2000 mL gas wash bottles

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes
- Abiotic sterile control: No
- Toxicity control: Yes
- Solvent control: Yes

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

66.9

Sampling time:

28 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The degradation of Alcohols, C18-22, distn. residues was 66.9% of ThCO2 at the end of the test

Executive summary:

The biodegradability of Alcohols, C18-22, distn. residues was assessed in an OECD 301B guideline study following GLP.

Activated sludge from the municipal wastewater treatment plant AZV, Breisgauer Bucht, Forchheim, was used as inoculum.

The degradation of the test item was 66.9% of ThCO2 at the end of the test (28 d after acidification, mean of four replicates).

Therefore the test item can be considered readily biodegradable.

The degradation of the toxicity control after 14 days was 61.4%. The test item had no inhibitory effect on the inoculum according to the criterion of the guideline.

Description of key information

Behenyl Bottoms, characterized as Alcohols, C18-22, distillation residues (CAS No. 1160164-88-4)were assessed for ready biodegradability in a reliable (Klimisch 1), GLP compliant OECD Guideline 301B (Ready Biodegradability: CO2 Evolution Test) and determined to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Type of water:

freshwater

Additional information

The biodegradability of Alcohols, C18-22, distn. residues was assessed in an OECD 301B guideline study following GLP (2018). The degradation was 66.9% at the end of the test (28 d), the test substance can therefore be considered as readily biodegradable, but failing the 10d-window. Due to the UVCB nature of the test substance, the 10d-window is considered of minor relevance, especially since the components can in general be characterised as a homologous series of substances with a certain range of carbon chain length and significant differences in degradability are not expected based on the structures.

In a former study, Behenyl Bottoms, characterized as Alcohols, C18-22, distillation residues (CAS No. 1160164-88-4)were assessed for ready biodegradability in a reliable (Klimisch 1), GLP compliant OECD Guideline 301B (Ready Biodegradability: CO2 Evolution Test). The test substance biodegraded to an extent of 84.1% after 60 days with an unacclimated sewage sludge inoculum. The test substance did not reach the criteria for ready biodegradability (60% degradation within a 28-day window). Consequently Behenyl Bottoms were determined to be inherently biodegradable.