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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 from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
It is considered appropriate to address the ready biodegradability data requirement for fatty acids, C12-20 and C12-20 unsatd., 2-ethylhexyl esters by applying read-across from available data on fatty acids, tall-oil, epoxidized, 2-ethylhexylesters (ETP) (a UVCB substance), given that both substances are of similar chemical structure, being long- chain esters with 2-ethyl hexanol. A read-across justification document is attached in section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
Parameter:
other: COD
Value:
70
Sampling time:
28 d

Table 1. Oxygen consumption in test flasks:

Time (days)

Cumulative oxygen consumption (mg/L)

Test item

Inoculum control

Procedure control

Abiotic control

Toxicity control

Flask No.

Flask No.

Flask No.

Flask No.

Flask No.

1

2

5

6

3

4

7

8

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

0

3

28

48

-

-

91

102

112

121

130

-

-

155

162

171

178

186

-

-

208

217

227

233

237

242

-

248

252

0

5

27

45

-

-

79

87

95

102

111

-

-

135

142

152

160

171

-

-

193

201

210

216

222

230

-

240

245

0

0

3

5

-

-

8

9

9

10

10

-

-

11

11

11

12

12

-

-

12

12

12

12

12

12

-

12

13

0

0

3

5

-

-

8

9

10

10

11

-

-

12

12

12

12

12

-

-

12

13

13

13

13

13

-

13

13

0

21

79

101

-

-

138

142

145

146

148

-

-

151

152

153

154

155

-

-

156

157

157

158

158

159

-

161

162

0

21

76

96

-

-

134

139

142

145

147

-

-

151

153

154

155

156

-

-

157

157

158

158

158

158

-

158

159

0

0

0

0

-

-

0

0

0

0

0

-

-

0

0

0

0

0

-

-

0

0

0

0

0

0

-

0

0

0

31

76

100

-

-

180

194

207

217

227

-

-

252

259

269

276

285

-

-

307

314

324

329

336

346

-

354

359

- No reading taken

Table 2: Biodegradation in the test flasks

Time (days)

Percentage biodegradation1

Test item

Procedure control

Toxicity control

Flask No.

Flask No.

Flask No.

1

2

3

4

8

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

0

1

7

13

-

-

25

28

31

33

36

-

-

43

45

48

50

52

-

-

59

61

64

66

67

69

-

70

72

0

1

7

12

-

-

21

23

25

27

30

-

-

37

39

42

44

47

-

-

54

56

59

60

62

65

-

68

69

0

13

46

57

-

-

78

80

81

81

82

-

-

84

84

85

85

86

-

-

86

87

87

87

87

88

-

89

89

0

13

44

54

-

-

75

78

79

81

82

-

-

84

85

85

86

86

-

-

86

87

87

87

87

87

-

87

87

0

6

14

19

-

-

34

37

39

41

43

-

-

48

49

51

52

54

-

-

58

60

62

63

64

66

-

68

69

Mean (day 28)

70

88

 

1Corrected for the mean oxygen uptake of the inoculums controls

- Not determined

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item fatty acids, tall-oil, epoxidized, 2-ethylhexylesters (ETP) was investigated for their ready biodegradability in a manometric respirometry test over 28 days according to EU Commission Directive 92/69 EEC, C.4-D (1992) and OECD Guideline for Testing of Chemicals No. 301 F (1992).

The percent biodegradation of the test item was calculated based on the chemical oxygen demand (COD) of 2.72 mg O2/mg test item. The biochemical oxygen demand (BOD) of ETP in the test media significantly increased from Day 1 until test-termination after 28 days. A continuous degradation of the test item was determined over the whole test period. At the end of the 28-day test period, the mean biodegradation of ETP amounted to 70%. Thus, ETP was found to be readily biodegradable under the conditions of the test within 28 days.
Executive summary:

It is considered appropriate to address the ready biodegradability data requirement for fatty acids, C12-20 and C12-20 unsatd., 2-ethylhexyl esters by applying read-across from available data on fatty acids, tall-oil, epoxidized, 2-ethylhexylesters (ETP), given that these substances are of similar chemical structure, being long- chain esters with 2-ethyl hexanol.

Based on read-across from ETP, C12 -20 and C12 -20 unsatd., 2 -ethylhexyl esters are considered to be readily biodegradable.

Description of key information

The test item fatty acids, tall-oil, epoxidized, 2-ethylhexylesters (ETP) was investigated for their ready biodegradability in a manometric respirometry test over 28 days according to EU Commission Directive 92/69 EEC, C.4-D (1992) and OECD Guideline for Testing of Chemicals No. 301 F (1992).

The percent biodegradation of the test item was calculated based on the chemical oxygen demand (COD) of 2.72 mg O2/mg test item. The biochemical oxygen demand (BOD) of ETP in the test media significantly increased from Day 1 until test-termination after 28 days. A continuous degradation of the test item was determined over the whole test period. At the end of the 28-day test period, the mean biodegradation of ETP amounted to 70%. Thus, ETP was found to be readily biodegradable under the conditions of the test within 28 days.

Read across from ETP. Both substances are of similar structure, being long-chain esters with 2-ethyl hexanol. See section 13 for a, attached document with a read across justification.

The substance Fatty acids, C12 -20 and C12 -20 -unsatd., 2 -ethylhexyl esters is therefore considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information