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Biodegradation in water: screening tests

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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: Results derived from a valid read across, with adequate and reliable documentation / justification.
Justification for type of information:
The read across justification is presented in the Endpoint summary. The corresponding documentation file is also attached there.
Reason / purpose:
read-across source
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 97
Sampling time:
28 d
Remarks on result:
other: Meeting the 10-day window criterion. Results are based on read across information.
Interpretation of results:
readily biodegradable
Conclusions:
For Acalea a biodegradation value of 97% has been derived after 28 days, meeting the 10-day window criterion. Therefore the substance is considered to be readily biodegradable.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from May 1992 to June 1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The test was carried out following OECD Guidelines (301F) without deviations. However, it was not done under GLP and therefore we cannot assign a Klimisch 1 score although we think its a totally reliable test
Justification for type of information:
Information was used for read across to Acalea.
Reason / purpose:
read-across: supporting information
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Deviations:
no
GLP compliance:
no
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): fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage. It came from a treatment plant in the City of Geneva, Aïre, Switzerland
- Storage conditions: it was kept under aerobic conditions
- Storage length: It was collected in the morning and used on the same day
- Preparation of inoculum for exposure: in each flask, a volume of suspended sludge corresponding to 7.5 mg dry weight was added
- Pretreatment: the sludge was washed 3 times in the mineral medium (by centrifuging at 1000g for 10 minutes, discarding the supernatant and resuspending in mineral medium).
- Concentration of sludge: 30 mg/L
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 100 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: see below
- Test temperature: 25 ºC
- pH: from 7.4 to 8.1
- pH adjusted: no
- Aeration of dilution water: no data
- Continuous darkness: no data


TEST SYSTEM
- Measuring equipment: Oxygen uptakes were read on the SAPROMAT meters
-others: the oxygen consumption of each flask was recorded everyday and the pH of each flask was measured at the beginning and at the end of the experiment.


CONTROL AND BLANK SYSTEM
- Inoculum blank: no
- Abiotic sterile control: not applicable
- Toxicity control: yes using aniline 99% pure as reference substance

Reference substance:
aniline
Remarks:
99% pure
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 97
Sampling time:
28 d
Details on results:
The 10-day window criterion is fulfilled: 15% biodegradation on day 4 and 87% on day 14
Results with reference substance:
the % of biodegradation of the reference substance was 61 after 28 days

The toxicity control attained a mean degradation of 94% in 28 days and therefore the test substance did not show a toxic effect to the micro-organisms at the test concentration

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Hexyl Cinnamic Aldehyde underwent 97% biodegradation after 28 days in the test conditions. The 10-day window criterion was also fulfilled. Thus, Hexyl Cinnamic Aldehyde should be regarded as Readily Biodegradable according to this test
Executive summary:

The Biodegradability of the test material was analysed by the determination of Oxygen consumption at frequent intervals over a period of 28 days. The method used was the Manometric Respirometry test according to OECD Guidelines (301F). Hexyl Cinnamic Aldehyde underwent 97% biodegradation after 28 days in the test conditions. The 10-day window criterion was also fulfilled. The curves obtained with the reference substance alone and with Hexyl Cinnamic Aldehyde + reference substance show no toxic effect of the test substance at the test concentration (100 mg/L). Thus, Hexyl Cinnamic Aldehyde should be regarded as readily biodegradable according to this test.

Description of key information

Acalea is readily biodegradable based on read across from Hexyl Cinnamic Aldehyde (tested in an OECD TG 301F).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

First the experimental information from the source is presented and thereafter the read across justification.

Hexyl Cinnamic Aldehyde and its ready biodegradability (as copied from the Lead registrant)

"The Biodegradability of the test material was analysed by the determination of Oxygen consumption at frequent intervals over a period of 28 days. The method used was the Manometric Respirometry test according to OECD Guidelines (301F). Hexyl Cinnamic Aldehyde underwent 97% biodegradation after 28 days in the test conditions. The 10-day window criterion was also fulfilled. The curves obtained with the reference substance alone and with Hexyl Cinnamic Aldehyde + reference substance show no toxic effect of the test substance at the test concentration (100 mg/L). Thus, Hexyl Cinnamic Aldehyde should be regarded as readily biodegradable according to this test".

Acalea (Cas no. 84697-09-6) and its ready biodegradability in water using read across information from Hexyl Cinnamic Aldehyde (Cas no. 165184-98-5).Introduction and hypothesis for the analogue approach

Acalea is an amyl cinnamic aldehyde with an additional methyl group at the para position. For this substance no data on biodegradation in water – screenings- system is available.

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 Acalea in water the analogue approach is selected because for one closely related analogue, Hexyl Cinnamic Aldehyde, reliable biodegradation data is available which can be used for read across.

Hypothesis: Acalea is expected to have similar biodegradability compared toHexyl Cinnamic Aldehyde (HCA) .Available experimental information: Hexyl Cinnamic Aldehyde was tested according to OECD Guideline 301F (Kl 2 because not GLP) and 97% of the substance was biodegraded after 28 days meeting the 10 day window criterion, resulting in ready biodegradability.

Target chemical and source chemical(s)

Chemical structures of Acalea and Hexyl Cinnamic Aldehyde are shown in the data matrix, including physico-chemical properties thought relevant for biodegradation.

Purity / Impurities

Acalea is a mono-constituent with a purity of ≥ 90 %. The impurities are all below 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 justification:In the RIFM database and OECD Toolbox (using Tanimoto on atom pairs > 60%) three closely related structures were found for possible read across, Amyl Cinnamic Aldehyde (Cas no. 122-40-7), Hexyl Cinnamic Aldehyde (HCA, Cas no. 165184-98-5) and Butyl Cinnamic Aldehyde (Cas no. 7492-44-6). In view of HCA containing one methyl group more in the alkyl chain than Amyl Cinnamic Aldehyde, resulting in the same molecular formula and weight as Acalea, this substance is the preferred analogue for read across to Acalea.

Structural similarities and differences:Acalea and HCA are similar because both have a cinnamic aldehyde with an alkyl chain as a backbone and functional group.The difference is thatAcalea, in contrast to HCA, contains a para-substituted methyl group,whereasHCA contains an additional methyl group in the alkyl chain. This means that besides having the same backbone both substances have the same molecular weight

Bioavailability:Acalea and HCA are expected to have similar bioavailability based on the similarity in chemical structure and physico-chemical properties. The molecular weight of both substances is 216.32. They are both liquids and have similar Log Kow’s of 5.2 and 5.3; and their vapour pressures are 0.017 and 0.068, respectively. It can be seen that the water solubility of Acalea is somewhat higher than of HCA (12.7 mg/L and 1.62 mg/L, respectively)which may be due to experimental variability as based on EPISUITE predictions similar water solubility is to be expected.

Similarity in reactive and biodegradable groups:Acalea and HCA have a similar biodegradability potential based on the high similarity in backbone and functional group. This is supported by BIOWIN which presents similar type of fragment profile (Table 1) for both substances. The ready biodegradability potential for BIOWIN 5 are 0.7586 and 0.7747, respectively and for BIOWIN 6 0.8289 and 0.8606, respectively.

Table 1. The type of biodegradable groups of Acalea and Hexyl Cinnamic Aldehyde as presented by BIOWIN 5 and 6.

Fragment

Acalea

HexylCinnamicAldehyde

 

Type of fragments

Type of fragments

Aldehyde [-CHO]

1

1

Aromatic-CH3

1

 

Aromatic-H

4

5

Methyl [-CH3]

1

1

-CH2- [Linear]

4

5

-C=CH [Alkenyl Hydrogen]

1

1

Uncertainty of the prediction: In view of the reasoning above there are no remaining uncertainties.

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 Acalea

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.

Hexyl Cinnamic Aldehyde (HCA) is ready biodegradable, meeting the 10-day window in an OECD Guideline 301F (Reliability 2, non GLP)). In view of the similarities in structure between Acalea and HCA this HCA information can be directly used for Acalea.

Final conclusion on fate: Acalea is readily biodegradable meeting the 10-day window.

Data matrix of Acalea using read across from Hexyl Cinnamic Aldehyde.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Common names

Acalea

Hexyl Cinnamic Aldehyde

Chemical structures

Empirical formula

C15H20O

C15H20O

Cas no

84697-09-6

165184-98-5

101-86-0

EC numbers

283-718-9

639-566-4

Reach registration

Registered for 2018

Registered for 2010

Physico-chemical data

 

 

Molecular weight

216.32

216.32

Physical state

Liquid

Liquid

Vapour pressure Pa (measured)

0.017

0.068

(ECHA dissemination site)

Water solubility mg/L (measured)

12.7

1.62

(ECHA dissemination site)

Water solubility mg/L (EPISUITE)

2.46 – 5.59

2.75 – 5.44

Log Kow (measured)

5.2

5.3

(ECHA dissemination site)

Fate

 

 

Biodegradation %

Read across from Hexyl Cinnamic Aldehyde

Readily biodegradable

(OECD TG 301F)