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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:
11 June 1990 - 9 July 1990
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
Study performed according to OECD Guideline 301B but in sealed vessels according to internationally accepted protocol (Sealed vessel TIC test acc. to Birch and Fletcher 1991). Performed in compliance with GLP. However, the results of this key study are compiled in a summary report only representing the most crucial results which does not contain sufficient data to recalculate the results.
Reference:
Composition 1
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Version / remarks:
The test was done before this method was officially accepted
Deviations:
no
GLP compliance:
yes
Test material information:
Composition 1
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): Secondary effluent from an unacclimatised activated sludge plant at URL North
- Preparation of inoculum for exposure: the activated sludge plant secondary effluent was filtered through Whatman filter paper (541) to remove coarse particulate matter
- Pretreatment: The level of dissolved inorganic carbon (DIC) was reduced by sparging the filtered effluent with nitrogen after prior adjustment of the pH to 6.5
- Concentration of sludge: 10% by volume
Duration of test (contact time):
28 d
Initial conc.:
12.14 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral salts medium as recommended in the 1988 OECD ring test (standard according to OECD 310)
- Test temperature: air temperature 17-22°C, temperature of liquid medium 21-23°C

TEST SYSTEM
- Culturing apparatus: 160 ml vessels (hypovials) containing 100 ml mineral salts medium inoculated with secondary effluent and the respective test substance or reference substance
- Number of culture flasks/concentration: multiple
- Method used to create aerobic conditions: headspace of vessels filled with air (60mL), containing approx. 6 times the mass of oxygen required for the complete oxidation of the substance
- Measuring equipment: Ionics 555 Inorganic Carbon Analyser for measurement of CO2/DIC (headspace gas and liquid medium)
- Test performed in closed vessels due to significant volatility of test substance: yes, vessels are sealed with a butyl rubber septum and an aluminium crimp seal/

SAMPLING
- Sampling frequency: day 3, 7, 10, 14, 18, 21, 24 and 28
- Sampling method: At each interval a vessel is removed and the carbon dioxide concentration of the headspace gas determined. The seal of the vessel is then broken and the concentration of inorganic
carbon in the test medium also determined.

CONTROL AND BLANK SYSTEM
- Inoculum blank: control vessels are identical to the test vessels except for the omission of test substance
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
106.3
Sampling time:
28 d
Remarks on result:
other: mean of four samples, 95% confidence limits 103.3% - 109.2%

Percentage biodegradation for Etaphen

Day No

% Biodegradation (a)

3

51.8

7

68.2

10

78.6

14

93.1

18

76.8

21

86.9

24

88.4

28

106.3 (b)

(a) Based on nominal carbon concentration which assumes 100% purity of the test substance

(b) Mean of 4 samples only

Validity criteria fulfilled:
yes
Remarks:
although the results relevant for the validity criteria have not been fully reported
Interpretation of results:
readily biodegradable
Conclusions:
Etaphen can be classified as readily and ultimately biodegradable based on the result of 106.3% degradation in 28 days in an OECD TG 301B sealed vessel test (~ TG310).
Executive summary:

The ready biodegradability of Etaphen was investigated in a study conducted according to OECD TG 301B sealed vessel test (prior to the acceptance of the OECD TG310) and in accordance with GLP. The concentration tested was 12.14 mg carbon/l. The percentage biodegradation was determined by determining the total Inorganic Carbon in the headspace gas as well as the liquid medium. The test showed 106.3% biodegradation after 28 days and the test substance can therefore be classified as 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:
Executive summary: The ready biodegradability of Peomosa is assessed by using read across from Etaphen (60-12-8) which results in Peomosa being readily biodegradable. Full details are provided in the study record. Structural similarities and differences: The target and the source chemical are both phenylethanols. The difference is an additional methyl group attached to the phenyl ring at the ortho-position in Peomosa, which is not present in Etaphen. They are both liquids and their physico-chemical properties are very similar. Bioavailability: The molecular weight and the physico-chemical properties are all in the same range for both Peomosa and Etaphen indicating availability for micro-organisms. Reactivity: There are no differences in functional groups between Peomosa and Etaphen that would hinder biodegradation. Uncertainty of the read across: There are no remaining uncertainties. The substances are very alike and thus the biodegradability of Etaphen can be used for Peomosa as presented above.
Reason / purpose:
read-across source
Related information:
Composition 1
Test material information:
Composition 1
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
106.3
Sampling time:
28 d
Remarks on result:
other: mean of four samples, 95% confidence limits 103.3% - 109.2%
Details on results:
No further details reported
Results with reference substance:
No information available

Percentage biodegradation for Phenyl ethyl alcohol

Day No

% Biodegradation (a)

3

51.8

7

68.2

10

78.6

14

93.1

18

76.8

21

86.9

24

88.4

28

106.3 (b)

(a) Based on nominal carbon concentration which assumes 100% purity of the test substance

(b) Mean of 4 samples only

Validity criteria fulfilled:
yes
Remarks:
although the results relevant for the validity criteria have not been fully reported
Interpretation of results:
readily biodegradable
Conclusions:
Peomosa can be classified as readily and ultimately biodegradable based on the result of the read across substance Phenyl ethyl alcohol being 106.3% degradation in 28 days in an OECD TG 301B sealed vessel (~ TG310) test.
Executive summary:

Peomosa is concluded to be readily biodegradable based on the result of the read across substance Phenyl ethyl alcohol. The ready biodegradability of Phenyl ethyl alcohol was investigated in a study conducted according to OECD TG 301B sealed vessel test (prior to the acceptance of the OECD TG310) and in accordance with GLP. The concentration tested was 12.14 mg carbon/l. The percentage biodegradation was determined by determining the total Inorganic Carbon in the headspace gas as well as the liquid medium. The test showed 106.3% biodegradation after 28 days and the test substance can therefore be classified as readily biodegradable.

Description of key information

Peomosa is concluded to be readily biodegradable based on the result of the analogue substance Etaphen tested in an OECD TG310.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

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

Biodegradation study with Etaphen:

The ready biodegradability of Etaphen was investigated in a study conducted according to OECD TG 301B sealed vessel test (prior to the acceptance of the OECD TG310) and in accordance with GLP. The concentration tested was 12.14 mg carbon/l. The percentage biodegradation was determined by determining the total Inorganic Carbon in the headspace gas as well as the liquid medium. The test showed 106.3% biodegradation after 28 days and the test substance can therefore be classified as readily biodegradable.

Peomosa and its ready biodegradability in water using read across information from Etaphen

 

Introduction and hypothesis for the analogue approach

Peomosa is a primary alcohol. For this substance no data on biodegradation are available in waterscreenings- system.

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 the analogue approach is selected because for one closely related analogue reliable a ready biodegradation can be derived.

Hypothesis: Peomosa has a similar degradation pattern in water as Etaphen because it has a similar structure.

Available experimental information: The source chemical Etaphen has biodegradability information from a GLP guideline TG301B (incl. sealed vessel adaptation for volatile substances) ready biodegradation test, rated with a Klimisch reliability score of 2 (based on somewhat limited documentation). The study shows that the substance is 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 relevant for biodegradation are listed in there. 

Purity / Impurities

The purity, the constituents and impurities of the target chemical do indicate a similar biodegradation potential. 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.In accordance with ECHA Guidance (2015, RAAF), Etaphen was selected being the closest analogue for which biodegradation information was available. Etaphenwas selected based on structural similarity and the presence of useful data for read-across, out of all analogues identified in the OECD QSAR toolbox and analogues identified in the RIFM database.

Ready Biodegradation and relevant parameters for read across:

Structural similarities and differences: The target and the source chemical are both phenylethanols. The difference is an additional methyl group attached to the phenyl ring at the ortho-position in Peomosa, which is not present in Etaphen. They are both liquids and their physico-chemical properties are very similar.

Bioavailability: The molecular weight and the physico-chemical properties are all in the same range for both Peomosa and Etaphen indicating availability for micro-organisms.

Reactivity: There are no differences in functional groups between Peomosa and Etaphen that would hinder biodegradation.

Uncertainty of the read across:There are no remaining uncertainties. The substances are very alike and thus the biodegradability of Etaphen can be used for Peomosa as presented above. Therefore, in the ECHA guidance (RAAF, 2015) terminology it receives a score of 5 (acceptable with high confidence), because the rationale for the selection of the analogues is clearly documented and there is supporting evidence provided.

Data matrix

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

Conclusions on the ready biodegradability for C&L Peomosa

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. In view of the structural similarities, the bioavailability and reactivity similarities between these two substances Etaphen can be used for read across to Peomosa.Etaphen is readily biodegradable and therefore also Peomosa is readily biodegradable.

Final conclusion: Peomosa is readily biodegradable.

 

Data matrix of Peomosa using read across from Etaphen

Common names

Peomosa

Etaphen

Chemical structures

CAS number

19819-98-8

60-12-8

Empirical formula

C9H12O

C8H10O

Molecular weight

136.94

122.17

Physico-chemical properties

 

 

Appearance

Liquid

Liquid

Vapour pressure at 25oC (Pa)

1.9 (measured)

3.24 (EpiSuite)

Water solubility at 20oC (mg/L)

12339(measured) 

21990 (EpiSuite)

Log Kow

2.1 (measured)

1.6 (EpiSuite)

Biodegradation % (28 days)

 Read across to Etaphen

 106