RD 14156

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:

The study was conducted between 05 April 2016 and 18 May 2016

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)

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

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

Deviations:

no

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 835.3110 (Ready Biodegradability)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch no.of test material: 539956P10
- Expiration date of the lot/batch: 25 January 2020
- Purity test date: 100% UVCB

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature in the dark
- Stability under test conditions: No data
- Solubility and stability of the test substance in the solvent/vehicle: Insoluble in water

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Loughborough sewage treatment plant, Leicestershire, UK
- Storage conditions: Aeration at 19-21oC prior to use
- Storage length: 6 days
- Preparation of inoculum for exposure: Filtered through coarse filter paper, maintained on aeration in temp controlled room at 19-21oC
- Pretreatment: No data
- Concentration of sludge: No data

Duration of test (contact time):

>= 28 d

Initial conc.:

>= 100 mg/L

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: OECD test medium
- Test temperature: 20-21oC
- pH: 7.4-7.5
- pH adjusted: no
- Aeration of dilution water: No data
- Suspended solids concentration: No data
- Continuous darkness: Diffuse light

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 23

Sampling time:

28 d

Day	% Biodegradation
	Test item	Toxicity control	Reference item
0	0	0	0
5	7	6	51
10	15	39	64
15	17	45	68
20	20	49	71
25	22	51	73
28	23	53	75

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Test item attained 23% biodegradation after 28 days, and therefore is not readily biodegradable under the conditions of the test. The reference item attained 75% biodegradation after 14 days indicating the sewage sludge inoculum was responding normally. The toxicity control attained a maximum of 53% biodegradation after 28 days indicating the test item was not toxic to the sewage treatment micro-organisms used in the test.

Executive summary:

A study was performed to determine the ready biodegradabilty of the test item when exposed to sewage treatment micro-organisms under aerobic conditions. The test was conducted according to the principles of GLP and followed internationally accepted test guidelines.

Sewage sludge was exposed to an aqueous dispersion of the test item at the nominal test concentration of 100 mg/L over a period of 28 days. The respiration rate (CO2 evolution) was measured daily throughout the test period and the % biodegradation calculated. The test validity criteria were met and the study is therefore acceptable. The reference item attained 75% biodegradation after 14 days indicating the test inoculum was responding normally. The toxicity control attained a maximum of 53% biodegradation after 28 days indicating the test item was not toxic to the sewage treatment micro-organisms used in the test.

The test item attained 23% biodegradation after 28 days and therefore is not readily biodegradable under the conditions of the test.

Description of key information

The study was performed to assess the ready biodegradability of RD 14156 (the test item) in an aerobic aqueous media. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No. 301F, “Ready Biodegradability; Manometric Respirometry Test” referenced as method C.4-D of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph (q)).

The test item at a concentration of 100 mg/L was exposed to sewage treatment micro-organisms with mineral medium in sealed culture vessels in diffuse light at temperatures of between 19 and 21 ºC for 28 days. The biodegradation of the test item was assessed by the measurement of daily oxygen consumption values on Days 0 to 28. Control solutions with inoculum and the reference item, aniline, together with a toxicity control were used for validation purposes.

The test item attained 23% biodegradation after 28 days and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.