Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: screening tests
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2010
Reliability:
1 (reliable without restriction)
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: OECD Series on Testing and Assessment No. 69
Principles of method if other than guideline:
GUIDANCE DOCUMENT ON THE VALIDATION OF (QUANTITATIVE) STRUCTURE-ACTIVITY RELATIONSHIP [(Q)SAR] MODELS
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
The endpoint information of the 1,1-cyclohexanediacetic acid monoamide (CAM) was used to predict the same endpoints for the target cyclohexanediacetic acid (CDA)

Study design

Oxygen conditions:
not specified
Inoculum or test system:
not specified

Results and discussion

Details on results:
According to the analysis performed the identified analog, i.e. 1,1-cyclohexanediacetic acid monoamide (CAM), can be considered structurally sufficient similar to the target, cyclohexanediacetic acid (CDA), to read-across the experimental test result of biodegradability of 1,1-cyclohexanediacetic acid monoamide (CAM) (RCC study n.849549) to CDA, concluding that CDA is readily biodegradable.
The readily biodegradability of CDA is further supported by the structural features known to enhance biodegradation, i.e. the presence of only C, H, N, and O atoms; the presence of CO bonds and acyclic structures as well as acid, ester and anhydride groups.
Finally the BIOWIN software package predicts cyclohexanediacetic acid (CDA) as ready biodegradable.

Any other information on results incl. tables

Since read-across represents a limited and ad hoc approach to grouping, it is important to provide supporting information that strengthens the case for the read-across. Thus, in addition to the endpoint being read-across, it is considered also useful to show that the analog and the target are (qualitatively or quantitatively) similar with respect to additional properties, relevant to the endpoint. The vast majority of models for biodegradability are hydrophobicity based as mentioned by Pavan et al., (M. Pavan & A.Worth, QSAR Comb.Sci., 27, 2008,1, 32 – 40). The comparison of CAM and CDA in terms of the above mentioned physicochemical properties is illustrated in the table below.

Structure

MW

LogP

LogD (pH 5.5)

LogD (pH 7.4)

CAM

199.25

0.71

-0.14

-1.93

CDA

200.23

1.27

-0.41

-3.37

* LogD values were calculated with ACD/labs (free web version).

In addition, more complex models and approaches were also proposed as mentioned by Pavan et al., (M. Pavan & A.Worth, QSAR Comb.Sci., 27, 2008,1, 32 – 40), based on structural requirements for slow and fast biodegradation. The selected structural descriptors included nitro groups, number of rings, number of CO bonds, and molecular weight. Biodegradation was found to be enhanced by: low molecular weight, the presence of only C, H, N, and O atoms; the presence of CO bonds and acyclic structures as well as acid, ester and anhydride groups. Biodegradation was found to be slowed by the presence of rings, quaternary carbons, tertiary and aromatic amines. These rules further support the similar behaviour of the two structures, 1,1-cyclohexanediacetic acid monoamide (CAM) and cyclohexanediacetic acid (CDA), with respect to biodegradability.

Thus, it can be concluded that the two structures are similar enough with respect to the structural and physicochemical properties relevant to the biodegradability to support the read-across.

Conclusions

The identified analog, i.e. 1,1-cyclohexanediacetic acid monoamide (CAM), can be considered structurally sufficient similar to the target, cyclohexanediacetic acid (CDA), to apply the read-across approach. In addition, the read-across between CAM and CDA is further supported by their similarity with respect to the structural and physicochemical properties relevant to the biodegradability. Therefore, the experimental test result on biodegradability of 1,1-cyclohexanediacetic acid monoamide (CAM) (RCC study n.849549) can be read-across to CDA, concluding that CDA is readily biodegradable.

QSAR MODEL

Endpoint: Ready biodegradability.

Tool

Prediction

BIOWIN

YES

 

1. BIOWIN

Prediction of ready biodegradability:YES

CONCLUSIONS

According to the analysis performed the identified analog, i.e. 1,1-cyclohexanediacetic acid monoamide (CAM), can be considered structurally sufficient similar to the target, cyclohexanediacetic acid (CDA), to read-across the experimental test result of biodegradability of 1,1-cyclohexanediacetic acid monoamide (CAM) (RCC study n.849549) to CDA, concluding that CDA is readily biodegradable.

The readily biodegradability of CDA is further supported by the structural features known to enhance biodegradation, i.e. the presence of only C, H, N, and O atoms; the presence of CO bonds and acyclic structures as well as acid, ester and anhydride groups.

Finally the BIOWIN software package predicts cyclohexanediacetic acid (CDA) as ready biodegradable.

Applicant's summary and conclusion

Interpretation of results:
readily biodegradable
Conclusions:
The BIOWIN software package predicts cyclohexanediacetic acid (CDA) as ready biodegradable.