Cyclohexanediacetic acid

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

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

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

Test material information

Constituent 1

Reference substance name:

Cyclohexanediacetic acid

EC Number:

224-427-9

EC Name:

Cyclohexanediacetic acid

Cas Number:

4355-11-7

Molecular formula:

C10H16O4

IUPAC Name:

2-[1-(carboxymethyl)cyclohexyl]acetic acid

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)

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Study design

Test type:

other: in silico prediction

Results and discussion

Effect concentrations

Dose descriptor:

EC50

Effect conc.:

432.25 mg/L

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 acute aquatic toxicity on algae are hydrophobicity based, however, more complex models and approaches were also proposed as mentioned by Netzeva et al., (T. Netzeva et al., QSAR Comb.Sci., 27, 2008,1, 77 – 90), based on electrophilic parameters, H bonding acceptors and donors, as well as solubility. The comparison of CAM and CDA in terms of the above mentioned physicochemical properties is illustrated in the table below.

Structure	MW	LogP	H bonding acceptors	H bonding donors	Solubility in pure water (mg/ml)
CAM	199.25	0.71	4	3	6.77 (pH 3.1)
CDA	200.23	1.27	4	2	10.18 (pH 2.86)

It can be concluded that the two structures are similar enough with respect to their physicochemical properties relevant to the acute toxicity on algae 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 physicochemical properties relevant to the acute toxicity on algae. Therefore, the experimental test result on the acute toxicity on algae of 1,1-cyclohexanediacetic acid monoamide (CAM) (RCC study n.849546) can be read-across to CDA, concluding that CDA is not toxic on algae.

QSAR MODEL

Endpoint: Acute aquatic toxicity on Green algae.

Tool	Prediction EC50(mg/L)	Applicability domain
ECOSAR	432.25	Max LogP = 6.4

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

ECOSAR
Prediction of Effective Concentration at 96-hour (EC50 mg/L): 432.25
ECOSAR: Conclusions
CDA is predicted not toxic on Green algae, being the estimated EC50 mg/L equal to 432.25.