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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:
Dec 12, 2007 - Jan 31, 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study was conducted according to an internationally recognised method, and under GLP. Deviations were reported. In the opinion of the Study Director, the above changes did not adversely affect the validity of the study. The substance is adequately characterised. Therefore full validation applies.
Cross-reference
Reason / purpose for cross-reference:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
other: Directive CEE/92/69 - Method C4E Méthode en bouteilles fermées
Deviations:
yes
Principles of method if other than guideline:
The stud y was conducted according to the approved stud y protocol with the fol low ing changes:
- The incubation period was prolonged to 36 days so as to ascertain that the plateau was reached on day 28.
- Noreenal is a volatile substance and care was taken to avoid undue agitation of the test solution before the BOD bottles were stoppered. For that purpose the BOD bottles were individually prepared : 250 mL of mineral medium were added with 20 µL of the Noreenal stock solution and stirred for a few seconds. The volume was added with 50 mL of mineral medium and 0.2 mL of pre-conditioned medium, resulting in a 2.03 mg/L solution . The vessels of the other groups were prepared accordingly.
In the opinion of the Study director, the validity of the results was not adversely affected by the above changes.
GLP compliance:
yes (incl. QA statement)
Remarks:
GLP certificate is available in Annex III of the full report (attached)

Test material

Constituent 1
Reference substance name:
NOREENAL (TM)
IUPAC Name:
NOREENAL (TM)
Test material form:
other: Liquid
Details on test material:
batch N ° 862036
Hydrosolubility = 34.8 mg/L (See Phytosafe study under 07-42-050-ES)
ThOD 2.95 g/g

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic (adaptation not specified)
Details on inoculum:
The freshly collected sample of surface water was previously pre-conditioned to the experimental conditions under aerobic conditions for 6 days in the mineral medium at the test temperature: 400 mL of surface water were added with 0.5 mL of the stock solutions A , B and C and 0.05 mL of the stock solution D and the volume was made to 500 mL.
The resulting solution was maintained under strong aeration and agitation at 20 ± 1°C for 6 days.
The preconditioned inoculum was further used at a rate of 0.7 Ml/L of medium .
The suspended solids were measured to represent 0.9 µg/L.
Duration of test (contact time):
ca. 28 d
Initial test substance concentration
Initial conc.:
ca. 2.02 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Remarks:
Degradation was followed by an alysi s of dissolved oxygen over a 28-day peri od
Details on study design:
Parallel groups of 250 mL BOD bottles were prepared of sufficient number to allow assessments every 3-4 days throughout the 28-day incubation period for each of the following experimental series:
- Blank group: mineral medium alone with inoculum (duplicate determination s),
- Solvent group: mineral medium with the same amount of chloroform as for the introduction of Noreenal (single determinations) , with inoculum,
- Test group: 2-5 mg/L test solution in mineral medium with inoculum (duplicate determinations) ,
- Reference group : 2-5 mg/L aniline solution in mineral medium with inoculum (duplicate determinations) ,
- Toxic control group: solution containing 2-5 mg/L of each the test substance and aniline in mineral medium, with inoculum (single determinations) .
Reference substance
Reference substance:
aniline
Remarks:
Test reference: Aniline , C6H5NH 2 , CAS no 62-53-3, Sigma Reference A9880 (> 99.0%), batch n°034KO 126.

Results and discussion

Test performance:
The test was considered as valid on the following conditions
- The oxygen uptake in the blank vessels should not be greater than 1.5 mg/L after 28 days,
- The residual concentration of oxygen in the test bottles should not fall below 0.5 mg/L at any time.
- Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-day window , as appropriate, should be less than 20% of mean value.
- Percentage degradation of the reference compounds should have reached the pass-level by day 14 (60% removal ofThOD).
- ln the toxic control series, containing both the test product and the reference substance, 25% biodegradation (based on total ThOD) , at least, should have occurred within 14 days. Otherwise the test substance would be assumed as inhibitory and the test should be repeated using a lower concentration of the test substance.
% Degradation
Parameter:
% degradation (O2 consumption)
Value:
ca. 57
Sampling time:
28 d
Remarks on result:
other: More values: see details on results
Details on results:
Points of degradation plot (test substance):
10 % degradation after 4 d
19 % degradation after 8 d
24 % degradation after 12 d
37 % degradation after 16 d
44 % degradation after 20 d
63 % degradation after 24 d
57 % degradation after 28 d
61 % degradation after 32 d
58 % degradation after 36 d


Days Test

Mean
Toxic Aniline

Mean
0 0 0 0
4 10.19 6.79 -7.51
8 18.54 13.85 40.92
12 24.06 41 .65 59.99
16 37.25 42.37 63.16
20 43.94 56.59 67.60
24 63.48 57.94 69.48
28 57. 13 58.94 68.00
32 60.89 60.30 71.75
36 57.97 58.58 67.70

BOD5 / COD results

Results with reference substance:
Points of degradation plot (reference substance):
0 % degradation after 4 d
41 % degradation after 8 d
60 % degradation after 12 d
63 % degradation after 16 d
68 % degradation after 20 d
69 % degradation after 24 d
68 % degradation after 28 d
72 % degradation after 32 d
68 % degradation after 36 d


Days Test

Mean
Toxic Aniline

Mean
0 0 0 0
4 10.19 6.79 -7.51
8 18.54 13.85 40.92
12 24.06 41 .65 59.99
16 37.25 42.37 63.16
20 43.94 56.59 67.60
24 63.48 57.94 69.48
28 57. 13 58.94 68.00
32 60.89 60.30 71.75
36 57.97 58.58 67.70

Time evolution of dissolved oxygen (mg/L) in the reacting vessel & Measured oxygen up-take (mg/L) throughout the 28-day incubation period tables are available in the full report (attached)

Any other information on results incl. tables

Dissolved oxygen still decreased between day 20 and day 24 of the incubation period in the test group, and the observation period was prolonged to 36 days so as to ascertain that the plateau was reached.

Mean oxygen uptake in the blank vessels was 1.15 mg/L at the end of test.

The consumption of oxygen was slightly higher in the solvent vessel ( 1.27 mg/L) at the end of test.

Aniline : The beginning of the 10-day window occurred between 4 and 8 days of incubation, and the pass­level was reached on day 12 (60% biodegradation). Final biodegradation on day 28 was 68.0 %.

Noreenal: The beginning of the 10-day window occurred on day 4 ( 10.2 % biodegradation), but on day 16, the percentage of biodegradation was still 37.2 %. The biodegradation still in creased on the followingdays: mean biodegradation was 57.1 % on day 28. The difference between extremes values on day 28 was (58.97-56.97) = 1.33% biodegradation, and represented 2.3% of mean value (57.13 %).

The incubation period was prolonged so as to ascertain that the plateau was reached on day 28: mean biodegradation appeared stabilized as 58.0 % was measured on day 36.

In the toxic control series, the biodegradation based on total ThOD was 41.7 % on day 12, and final value on day 28 was 58.9 %.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
The test was terminated after 36 days of incubation. The test was considered as valid on the basis of the fulfilled conditions
Interpretation of results:
other: not readily biodegradable
Conclusions:
The test was performed using a 2.03 mg/L test solution .
57.1 % biodegradation occurred within 28 days and the pass-level was almost reached, but this did not occurred within the 10-day window and Noreenal was not considered as easily biodegradable.
Based on analytic assessment, the removal of Noreenal in the test vessels at the end of test was total.
Executive summary:

TEST ITEM     NOREENAL, batch n°862036

STUDYReady biodegradability of a substance- Closed-bottle test

GUIDELINES  EEC  C4.e

 

RESULTS

Hydrosolubility = 34.8 mg/L

Theorical COD = 2.95 g/g

Nominal test concentration: 2.03 mg/L (5.98 mg ThOD/L)

Ready biodegradabilityNoreenal is NOT easily biodegradable (57% removal within 28 days)