Dimethyl heptanedioate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Remarks:

iSafeRat® Version 1.7

Adequacy of study:

key study

Study period:

2017-10-23 to 2017-10-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Remarks:

QSAR value. The substance falls into applicability domains of the model QSAR.

Justification for type of information:

See QMRF and QPRF in "attached background material" section.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

yes

Remarks:

QSAR model

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

yes

Remarks:

QSAR model

Principles of method if other than guideline:

The growth inhibition of algae was determined using validated QSAR model for the Mode of Action (MOA) in question (poly-esters). The QSAR model is based on validated data for a training set of 44 chemicals derived from 72-hour ErC50 test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

GLP compliance:

no

Specific details on test material used for the study:

None

Analytical monitoring:

no

Remarks:

QSAR model. See "any further information on material and methods incl. tables"

Details on sampling:

N/A

Vehicle:

no

Details on test solutions:

Not applicable

Test organisms (species):

other: Results from the following species were used in the regression: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda

Details on test organisms:

no data

Test type:

other: QSAR model. Following guideline OECD 201, all studies were from a static test design. For suspected volatile substances only tests performed in closed vessels were accepted unless accompanying analytical monitoring proved such a design was unnecessary.

Water media type:

not specified

Total exposure duration:

72 h

Remarks on exposure duration:

Results from a test duration of 72 hours only were used for this algorithm.

Post exposure observation period:

Not applicable

Hardness:

Not applicable

Test temperature:

The temperatures varied from approximately 20 to 25 °C depending on the species used to construct the algorithm.
This small difference is not expected to contribute to the variability of the ErC50 values found in experimental data.

pH:

Test results were preferably taken from studies with measured pHs between 6 - 9. However it is recognized that in some cases (due to high luminosity) the pH may increase in the control and lower concentrations (which do not cause significant effect over the study period). This pH increase did not generally disqualify the study from being used in the test and validation set for non-polar chemicals.

Dissolved oxygen:

Not applicable

Salinity:

Not applicable

Conductivity:

Not applicable

Nominal and measured concentrations:

Not applicable

Details on test conditions:

Not applicable

Reference substance (positive control):

no

Remarks:

QSAR model

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

207 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % CL [179 - 238 mg/L]

Details on results:

Not applicable

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

95% CL [179 - 238 mg/L] QSAR statistical parameters are given in the QMRF and the QPRF

None

Validity criteria fulfilled:

yes

Remarks:

The substance falls into applicability domains of the QSAR model

Conclusions:

72h-ErC50 for dimethyl pimelate = 207 mg test item/L with 95%-Confidence Limit of 179 - 238 mg test item/L.

Executive summary:

A Quantitative Structure-Activity Relationship (QSAR) was used to calculate the inhibition of growth to algae of the test item dimethyl pimelate. This QSAR model has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following the Guideline for Testing of Chemicals No. 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test", referenced as Method C.3 of Commission Regulation No. 440/2008. The criterion predicted was the ErC50 (Median Effective Concentration for specific growth rate), a statistically derived concentration which is expected to cause 50% inhibition of intrinsic rate of growth of the test system within a period of 72 hours.

 

The growth inhibition of algae was determined using validated QSAR model for the Mode of Action (MOA) in question (poly-esters). The QSAR model is based on validated data for a training set of 44 chemicals derived from 72-hour ErC50 test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

 

The 72 h-ErC50 (based on growth rate) is predicted as being 207 mg/L with 95 %-Confidence Limit between 179 and 238 mg test item/L.

Description of key information

72h-ErC50 for dimethyl pimelate = 207 mg test item/L with 95%-Confidence Limit of 179 - 238 mg test item/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

207 mg/L

Additional information

For that endpoint, aQuantitative Structure-Activity Relationship (QSAR) model was used. The purpose of this QSAR model is to accurately predict the inhibition of growth to freshwater algae of the registered substance as would be expected in a laboratory experiment following OECD Guideline 201, for specific, named modes of action, to provide a value that can effectively replace a 72-hour ErC50 value from an experimental study. The regression based method used to achieve this has been fully validated following theOECD recommendations for QSAR modeling (OECD, 2004).

The criterion predicted was the ErC50 (Median Effective Concentration for specific growth rate), a statistically derived concentration which is expected to cause 50% inhibition of intrinsic rate of growth of the test system within a period of 72 hours.

 

In this study, the growth inhibition of algae was determined using validated QSAR model for the Mode of Action (MOA) in question (poly-esters). The QSAR model is based on validated data for a training set of 44 chemicals derived from 72-hour ErC50 test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.

The experimental studies used to construct the algorithm were verified to fully satisfy the requirements of the OECD 201 guideline. In addition, studies were used only where analytical measurements were made on the control and all relevant test concentrations whenever possible. Any exceptions (initial concentrations measured only or ErC50 based on nominal values) were used only when sufficient justification for stability of the test item was determined.

 

To conclude, the QSAR model is considered valid and the substance falls within the applicability domain of the model. Therefore, this study is considered acceptable to replace an experimental study on the registered substance and can be used for that endpoint.

For further details, the QPRF and QMRF reports are attached to the relevant study record.