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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Justification for type of information:
It is considered appropriate to address data requirements for fatty acids, C14-22, 2-ethylhexyl esters, epoxidized via read-across to members of the epoxidised oils and derivatives group. Four epoxidised oils and esters (linseed, soybean,9-octadecanoate propylene glycol ester and 2-ethylhexyl tallate ester ETP) have been identified as sharing common structural and functional similarities, recognised in an OECD SIDS review as a single category, and therefore justifying read-across between data for different members of the group. The C14-C22, 2-ethylhexylesters are listed as similar products on the market to ETP based on fatty acids from other naturally occurring fatty acids. Consequently data sharing between ESBO epoxidised soybean oil, ELO epoxidised Linseed oil and ETP epoxidised 2-ethylhexyl tallate and fatty acids, C14-C22, 2-ethylhexylesters, epoxidised is considered appropriate.
Reason / purpose:
read-across source
Parameter:
% degradation (CO2 evolution)
Value:
79
Sampling time:
28 d
Remarks on result:
other: 10 mg test substance/L
Parameter:
% degradation (CO2 evolution)
Value:
92
Sampling time:
28 d
Remarks on result:
other: 20 mg test substance/L

Theoretical CO2 formation:

Reference Substance:                                                      20 mg/L = 85.061 mg CO2/1.5L

Test Substance:                                                                 10 mg/L = 39.13 mg CO2/1.5L

Test Substance:                                                                  20 mg/L = 78.26 mg CO2/1.5L

Table 1: CO2 Evolution and Biodegradation

DAY

Blank

Blank and vehicle

Aniline (Ref. Substance) 20 mg/L

 

Test Substance at 10 mg/L

Test Substance at 20 mg/L

CO2 Evolution

CO2 Evolution

CO2 Evolution

Biodegradation

CO2 Evolution

Biodegradation

CO2 Evolution

Biodegradation

[mg]

[mg]*

[mg]

[mg]*

[mg]

[mg]*

[%]

[%]*

[mg]

[mg]*

[%]

[%]*

[mg]

[mg]*

[%]

[%]*

5

2.7

2.7

4.2

4.2

16.1

16.1

19.0

19.0

16.3

16.3

41.8

42

42.1

42.1

53.8

54

11

6.4

9.2

6.1

10.3

47.3

63.4

55.6

74.5

10.3

26.7

26.4

68

19.0

61.1

24.3

78

18

7.6

16.8

7.7

18.0

7.2

70.6

8.4

83.0

3.0

29.7

7.7

76

6.5

67.6

8.3

86

22

3.7

20.4

4.0

22.0

3.8

74.4

4.5

87.4

-0.4

29.3

-0.9

75

0.1

67.7

0.1

87

27

7.3

27.7

5.6

27.6

5.9

80.2

6.9

94.3

1.5

30.9

3.9

79

3.4

71.2

4.4

91

28

1.2

28.9

1.7

29.3

0.1

80.3

0.1

94.4

-0.1

30.8

-0.2

79

1.2

72.3

1.5

92

* = cumulative values

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
A ready biodegradability test (OECD guideline 301B) was conducted on TK 11278 (otherwise known as Reoplast 39 or epoxidised soybean oil) using bacteria from a sewage treatment plant. Aniline was used as a reference substance.

After 28 days:

The biodegradation calculated as percentage of measured amount of CO2 over the theory was:
10 mg test substance/L = 79 % in 28 days
20 mg test substance/L = 92 % in 28 days

The % degradation (% ThCO2 formation) exceeded 10% within 2 to 3 days for both concentrations of the test material and subsequently exceeded the 60% pass level within the 10 day window.

Therefore, epoxidised soybean oil is readily biodegradable.
Executive summary:

It is considered appropriate to address data requirements for fatty acids, C14-22, 2-ethylhexyl esters, epoxidized via read-across to members of the epoxidised oils and derivatives group. Four epoxidised oils and esters (linseed, soybean,9-octadecanoate propylene glycol ester and  2-ethylhexyl tallate ester ETP) have been identified as sharing common structural and functional similarities, recognised in an OECD SIDS review as a single category, and therefore justifying read-across between data for different members of the group. The C14-C22, 2-ethylhexylesters are listed as similar products on the market to ETP based on fatty acids from other naturally occurring fatty acids. Consequently data sharing between ESBO epoxidised soybean oil, ELO epoxidised Linseed oil and ETP epoxidised 2-ethylhexyl tallate and fatty acids, C14-C22, 2-ethylhexylesters, epoxidised is considered appropriate.

Based on read-across from am OECD 301B ready biodegradability study conducted on TK 11278 (otherwise known as Reoplast 39 or epoxidised soybean oil), C14 -22, 2-ethylhexyl esters, epoxidized are considered to be readily biodegradable.

Description of key information

Soybean oil, epoxidised is considered to be readily biodegradable. This was proven in a study conducted by Dr. A.V. Schulthess in 1988 using OECD guideline 301B.

A ready biodegradability test was conducted on TK 11278 (otherwise known as Reoplast 39 or epoxidised soybean oil) using bacteria from a sewage treatment plant. Aniline was used as a reference substance.

After 28 days:

The biodegradation calculated as percentage of measured amount of CO2 over the theory was:

10 mg test substance/L = 79 % in 28 days

20 mg test substance/L = 92 % in 28 days

The % degradation (% ThCO2 formation) exceeded 10% within 2 to 3 days for both concentrations of the test material and subsequently exceeded the 60% pass level within the 10 day window.

Therefore, epoxidised soybean is readily biodegradable.

 

Read across to a study result from an investigation using a similar material is justified for members of the Epoxidised Oils and Derivatives group. Four epoxidised oils and esters (linseed, soybean,9-octadecanoate propylene glycol ester and  2-ethylhexyl tallate ester ETP) have been identified as sharing common structural and functional similarities, recognised in an OECD SIDS review as a single category, and therefore justifying read-across between data for different members of the group. The C14-C22, 2-ethylhexylesters are listed as similar products on the market to ETP based on fatty acids from other naturally occurring fatty acids. Consequently data sharing between ESBO epoxidised soybean oil, ELO epoxidised Linseed oil and ETP epoxidised 2-ethylhexyl tallate and fatty acids, C14-C22, 2-ethylhexylesters, epoxidised is commonly utilised in the preparation of this dossier.

Read-across bridges are used for members of the EOD group where appropriate, is justified based on similar toxicity profiles and structural and functional similarities.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information