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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
October 20, 2015 to December 14, 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study carried out according to internationally recognised guidelines and performed according to GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2015
Report date:
2015

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 835.3110 (Ready Biodegradability)
Deviations:
no
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
2-chlorocyclododecanone
EC Number:
679-917-9
Cas Number:
35951-28-1
Molecular formula:
C12H21ClO
IUPAC Name:
2-chlorocyclododecanone
Constituent 2
Reference substance name:
Chlorocyclododecanone
IUPAC Name:
Chlorocyclododecanone
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): Chlorocyclododecanone
- CAS Number: 35951-28-1
- Physical state: white powder
- Lot/batch No.: 15-E190P
- Expiration date of the lot/batch: Sept 29, 2016

Study design

Oxygen conditions:
anaerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland) was used. The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
Duration of test (contact time):
42 d
Initial test substance concentration
Initial conc.:
30 mg/L
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Apparatus
Respirometer: Oxitop Control System

Water
The water used during this study is ultrapure water, containing less than 5 ppb total organic carbon, produced by using a Millipore Direct-Q 3 UV purification system.

Stock solutions of mineral components
The following stock solutions were prepared:

Solution A:
KH2PO4: 8.5 g
K2HPO4: 21.75 g
Na2H PO4.2H2O: 33.4 g
NH4CI: 0.5 g
dissolved in water and made up to 1 litre.

Solution B:
CaCl2: 27.5g
dissolved in water and made up to 1 litre.

Solution C:
MgSO4•7H2O: 22.5g
dissolved in water and made up to 1 litre.

Solution D:
FeCI3.6H2O: 0.25g
HCI Conc.: one drop
dissolved in water and made up to 1 litre .

Mineral medium
Prepared by mixing 50 ml of solution A and 2000 ml deionised water, adding 5 ml of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide.

Toxicity of the test substance
As suggested in the OECD 301F method, the toxicity of the test substance for the inoculums is checked. Therefore a pair of flasks of the volumetric respirometer are filled with mineral medium + test substance (100 mg/L) + reference substance (100 mg/L) + inoculums and their respirations are recorded as for the other flasks. If they are lower than those of the flasks containing mineral medium + reference substance (100 mg/L) + inoculums, the test substance can be assumed to be inhibitory to the inoculums used.

Determination of the dry weight of suspended solids
The dry weight of suspended solids is determined by taking two 50 ml samples of the homogenised sludge, evaporating water on a steam bath, drying in an oven at 105 – 110 °c for two hours and weighing the residue.

Preparation of the flasks
Test substance samples (13.10 mg, corresponding to 30 mg/l in 437 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop. For reference substance samples 43.70 mg (corresponding to 100.0 mg/l in 437 ml of test medium) are weighed in small aluminium boats and added directly to the test flasks of the Oxitop.

Flasks are filled with 432 ml of mineral medium. Samples of test or reference substance are added. Then, a 5ml volume of suspended sludge corresponding to 2.62 g dry matter id added. Except when the test substance has an acid or alkaline character, the pH of each flask is not measured but assumed to be the same as the mineral medium, in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it. Neutral test substances, even sodium benzoate, were shown not to affect the pH of the medium by more than 0.1 pH unit. Two sodium hydroxide pellets are placed in the quivers on top of the bottle, and the flasks are closed tightly with the measuring heads. The measurement is started by programming the measuring unit on top of the Oxitop system. After temperature equilibration, the controller of the instrument starts the data aquisition (time zero of the experiment).

Performance of the test
Every day the oxygen consumption of each flask is recorded and correct temperature and stirring are checked. At the end of the test period (normally 28 days), the pH of each flask is measured again.

Test temperature: 21.3°C to 21.8°C
Test duration: 42 days
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
(Fluka, Buchs, Switzerland, Art. No. 71300) Purity: min. 99.0 %

Results and discussion

Test performance:
- Degradation of sodium benzoate exceeded 40 % after 7 days and 65 % after 14 days; the activity of the inoculum was thus verified (validity criterion).
- The repeatability validity criterion (not more than 20% difference between replicates) is fulfilled. Therefore, the test is considered valid.
- Therefore the test was considered valid.
% Degradationopen allclose all
Parameter:
% degradation (O2 consumption)
Value:
22
Sampling time:
9 d
Parameter:
% degradation (O2 consumption)
Value:
66
Sampling time:
9 d
Parameter:
% degradation (O2 consumption)
Value:
74
Sampling time:
28 d
Details on results:
Chlorocyclododecanone undergoes 74% biodegradation after 28 days in the test conditions. The 10-day window criterion is also fulfilled (22% biodegradation on day 9 and 66% on day 19).
Chlorocyclododecanone did significantly inhibit the intrinsic respiration of the inoculum at the test concentration at the beginning of the test. Toxicity towards the inoculum at the test concentration can therefore not be excluded.
Thus, Chlorocyclododecanone should be regarded as readily biodegradable according to this test.

BOD5 / COD results

Results with reference substance:
Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days. The activity of the inoculum was thus verified (validity criterion).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Chlorocyclododecanone undergoes 74% biodegradation after 28 days in the test conditions. The 10-day window criterion is also fulfilled (22% biodegradation on day 9 and 66% on day 19).
Chlorocyclododecanone did significantly inhibit the intrinsic respiration of the inoculum at the test concentration at the beginning of the test. Toxicity towards the inoculum at the test concentration can therefore not be excluded.
Thus, Chlorocyclododecanone should be regarded as readily biodegradable according to this test.
Executive summary:

Chlorocyclododecanone should be regarded as readily biodegradable according to this test.