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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:
For details and justification of read-across please refer to the attached report in section 13 of IUCLID.
Reason / purpose for cross-reference:
read-across source
Key result
Parameter:
% degradation (DOC removal)
Value:
ca. 93.57
Sampling time:
4 d
Key result
Parameter:
% degradation (DOC removal)
Value:
ca. 96.55
Sampling time:
28 d

The degradation of the test substane, the control and toxic control are detailed below:

Table 1: Percentage biodegradation

Day

test substance

positive control

toxicity control

A3

A4

mean

PK5

TK6

0

0

0

0

0

0

2

-3.29

69.70

33.20

87.34

1.26

4

93.34

93.80

93.57

92.87

89.80

7

93.92

93.48

93.70

91.26

92.83

10

96.15

95.03

95.59

95.07

92.86

14

96.81

96.81

96.81

95.94

95.33

18

96.10

94.87

95.49

95.60

94.83

22

95.99

96.02

96.00

97.66

97.12

25

96.58

95.86

96.22

93.69

94.64

28

96.56

96.55

96.55

97.93

96.75

Validity criteria fulfilled:
yes
Conclusions:
Succinic acid is readily biodegradable.
Executive summary:

The ready biodegradability of succinic acid was determined by measurement of the dissolved organic carbon content (DOC) at frequent intervals over a period of 28 days using OECD guideline 301E. The reference substance (sodium benzoate) was degraded by 95.9 % within 14 days. A toxicity control containing the reference substance and succinic acid indicated no inhibition of microbial activity due to the test substance.

The test substance, succinic acid, with a nominal starting concentration of 20 mg DOC/L (corresponding to 17 mg DOC/L in terms of succinic anhydride) was degraded by 96.6 % after 28 days of incubation at a mean temperature of 21.6 °C. The 10-d window as defined by the guidelines started at approximately day 1. 70 % degradation was exceeded at about day 4.

According to the guideline, succinic acid is readily biodegradable.

Succinic anhydride has been described as insoluble or very slightly soluble in water and is inherently unstable in aqueous media, rapidly hydrolysing to form succinic acid (Leslie & Moseley, 2010). This behaviour was confirmed during an attempted hydrolysis study. Therefore the behaviour of the substance succinic acid was investigated.

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Description of key information

The ready biodegradability of succinic anhydride was assessed using the hydrolysis product of the substance, succinic acid. The ready biodegradability of succinic acid was determined by measurement of the dissolved organic carbon content (DOC) at frequent intervals over a period of 28 days according to OECD guideline 301E.


The test substance, with a nominal starting concentration of 20 mg DOC/L, was degraded by 96.6 % after 28 days of incubation at a mean temperature of 21.6 °C. The 10-d window as defined by the guidelines started at approximately day 1. 70 % degradation was exceeded at about day 4. According to the guideline, succinic acid is readily biodegradable.


Succinic anhydride has been described as insoluble or very slightly soluble in water and is inherently unstable in aqueous media, rapidly hydrolysing to form succinic acid (Leslie & Moseley, 2010). Consequently, it can be safely assumed that succinic anhydride is also readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information