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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
18 November - 23 December 1997
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Reliability 1 is assigned because the study was conducted according to OECD TG 301D in compliance with GLP, without deviations that influence the quality of the results.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
Inoculum was coming from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aire). On the day of collection, the sample was washed three times in the mineral medium by centrifugation at 1000 g for 10 min, discarding the supernatant and resuspending in mineral medium.
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Test substance samples and reference substance samples are weighed. All flasks are filled with 250 ml of mineral medium. Samples of test or reference substance, or both, are added. The the sludge is added. The flasks are closed and placed in the water bath of the Sapromat. After temperature and pressure equilibration, the oxygen meters of the instrument are set to zero.
Reference substance:
benzoic acid, sodium salt
Test performance:
The test was performed at 22°C ± 1°C.
Everyday the oxygen consumption of each flask was recorded and correct temperature and stirring were checked. At the end of the test period, the pH of each flask was measured again.
Key result
Parameter:
% degradation (O2 consumption)
Value:
82
Sampling time:
28 d
Remarks on result:
other: 10-day window was met
Details on results:
The test material was biodegraded by 82 % after 28 days, therefore it is considered readily biodegradable. The criteria for meeting a 10-day window was also fulfilled. The results show that there was no toxic effect of the test substance on the microorganisms at the test concentration.
Results with reference substance:
The reference substance was biodegraded by 40 % after 7 days and by 65 % after 14 days.
Validity criteria fulfilled:
yes
Remarks:
Degradation of sodium benzoate exceeded 65% after 14 days.
Interpretation of results:
readily biodegradable
Conclusions:
The test material showed 82 % biodegradation after 28 days in an OECD TG 301 F test. The criteria for meeting a 10-day window were also fulfilled. Therefore, it is considered readily biodegradable.
Executive summary:

The ready biodegradability of the test substance was investigated in a study conducted in accordance with OECD TG 301 F and GLP. The concentration tested was 100 mg/l test substance, with an activated sludge concentration of 30 mg/l (2.28 g/l dry weight of suspended solids). The test substance biodegraded for 82 %. The 10-day window was met and therefore the substance was considered readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The information is derived from read-across
Justification for type of information:
The full read-across document can be found in the Endpoint Summary in text and in the attached file.
Reason / purpose:
read-across source
Key result
Parameter:
% degradation (O2 consumption)
Value:
82
Sampling time:
28 d
Remarks on result:
other: 10-day window was met
Interpretation of results:
readily biodegradable
Conclusions:
It can be concluded that the test substance is readily biodegradable.

Description of key information

Biodegradation (read-across for Veratraldehyde from Piperonal (CAS number 120 -57 -0)): readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The biodegradation is based on read across from Piperonal. First the study with the analogue is described and thereafter the read across justification is presented.

 

The ready biodegradability of Piperonal (CAS number 120 -57 -0) was investigated in a study conducted in accordance with OECD TG 301 F and GLP. The concentration tested was 100 mg/L test substance. The test substance biodegraded for 82% in 28 days and was not toxic to the inoculum. Profarnesal (CAS number 120 -57 -0) was concluded to be readily biodegradable.

Veratraldehyde and its ready biodegradability in water sediment using read across information from Piperonal (CAS number 120-57-0)

 

Introduction and hypothesis for the analogue approach

Veratraldehyde is a phenol structure with two short ether-alkyl chains attached in the meta and para positions of the phenol ring, both chains have one carbon. For Veratraldehyde data on biodegradation in a water – screening - system are lacking. In accordance with Article 13 of REACH,lacking information can be generated by means of applying alternative methods such as QSARs, grouping and read-across. For assessing the ready biodegradation of the substance in water - sediment the analogue approach is selected because for one closely related analogue a reliable ready biodegradability study is available.

Hypothesis: Veratraldehydeis expected to have similar biodegradation percentage as Piperonal based on a similar structure.

Available experimental information: For the analogue, Piperonal, an OECD 301 F test (GLP, K1) is available. It was biodegraded by 82% after 28 days, meeting the 10-day window criteria, which results in the substance being readily biodegradable.

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical are shown in the data matrix. Also physico-chemical properties thought to be relevant for biodegradation are listed in there.   

Purity / Impurities

Veratraldehyde is a mono-constituent. The impurities are below 2% (<10%).

Analogue approach justification

According to Annex XI 1.5, read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read across, the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation.

Analogue selection: Piperonal was selected because of the close structural similarity and adequate data were available. It was selected from all analogues identified in the OECD QSAR toolbox using Tanimoto similarity of 75% and analogues identified in the RIFM database.

Structural analogy: Veratraldehyde and Piperonal are both methyl phenyl aldehydes, with two ether bonds attached opposite the aldehyde group. The difference with Piperonal is that Veratraldehyde has two loose CH3 groups attached to the ether, while Piperonal has the ether bonds in a ring structure resulting in an acetal group.

Bioavailability: The similarity in bioavailability of both substances for bacteria can be assessed using the phys-chem properties of the source Piperonal and target Veratraldehyde. Both substances are well water soluble and have a low log Kow. Though Piperonal is somewhat less water soluble compared to Veratraldehyde(1400 mg/l and 14914, respectively)and has a slightly higher log Kow, this will not affect the biodegradation.   

Uncertainty of the prediction: There is limited uncertainty based on the reasoning above. In addition, the read across and the result is further supported by BIOWIN in EPISUITE, which predicts both substances to be readily biodegradable. Veratraldehyde (the target) is expected to be readily biodegradable: BIOWIN 5 and 6 show probabilities of 1.05 and 0.97, respectively, while the cut off is > 0.5 for ready biodegradable. For Piperonal these probability predictions are: 1.11 and 0.98, respectively. This further supports the likelihood of ready biodegradation of Veratraldehyde.

Data matrix

The relevant information on physico-chemical properties and biodegradation characteristics are presented in the data matrix below.

Conclusions on the ready biodegradability of Veratraldehyde

When using read across, the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation. Piperonal is readily biodegradable (OECD TG 301F), and therefore also Veratraldehyde is readily biodegradable.

Final conclusion on ready biodegradability: Veratraldehyde is readily biodegradable.

 

Data matrix of Veratraldehyde using read across from Piperonal.                                                                                                                                                                                                                                                                                                

Name of substance

Veratraldehyde

Piperonal

(Heliotropin)

Chemical structure

 

 

 

Cas no

120-14-9

120-57-0

Tanimoto

1

0.77

Einecs number

204-373-2

204-409-7

REACH

Registration 2018

Full registration

Empirical

C9H10O3

C8H6O3

Mol weight

166.18

150.13

Phys-chem

 

 

Appearance

White crystals or cream-colored, fused mass; solid (IFF, 2016)

Crystalline solid

Melting point (oC)

44.7°C (IFF, 2016)

36.5 ± 0.5°C (ECHA dissemination site)

Boiling point (oC)

262.8°C (IFF, 2016)

272 ± 2°C (ECHA dissemination site)

Vapour pressure (Pa at 25oC)

0.09 (IFF, 2016)

1.33 / 2.01(ECHA dissemination site)

Water solubility (mg/l)

14914 (IFF, 2016)

1400 (ECHA dissemination site)

Log Kow

0.8 (IFF, 2016)

1.2 (ECHA dissemination site)

Biodegradation %

Read-across from Piperonal

Readily biodegradable (82%after 28 days)

EPISUITE prediction

BIOWIN5 = 1.05, BIOWIN6 =0.97

BIOWIN5 = 1.11, BIOWIN6 =0.98