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Diss Factsheets

Ecotoxicological information

Short-term toxicity to aquatic invertebrates

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Administrative data

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
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
Justification for type of information:
See QMRF and QPRF in "attached background material" section.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
QSAR model
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
yes
Remarks:
QSAR model
Principles of method if other than guideline:
The immobility of the daphnids was determined using a 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 8 chemicals derived from 48-hour test on daphnids, 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:
Not applicable. See "any other information on material and methods incl. tables"
Details on sampling:
No data
Vehicle:
no
Details on test solutions:
Not applicable
Test organisms (species):
Daphnia sp.
Details on test organisms:
Results from the following species were used in the regression: Daphnia magna, Daphnia pulex
Following the principles of Phase Equilibrium Thermodynamics, for narcotic substances, no difference in relationship between solubility and ecotoxicity between invertebrate (or indeed other) aquatic species is expected. Any observed differences may be attributed to lifestyle related parameters (e.g. shell closing in molluscs) and relative duration of study versus bodysize rather than to a specific toxic mechanism causing species differences. In this case, for poly-esters compounds, no differences were observed in activity based toxicity for the 2 species used.
Test type:
other: QSAR model. See "details on test conditions"
Water media type:
not specified
Total exposure duration:
48 h
Remarks on exposure duration:
Results from a test duration of 48 hours only were used for daphnid and ceriodaphnid species.
Post exposure observation period:
Not applicable
Hardness:
Not specified
Test temperature:
The temperatures varied from approximately 20 to 23 °C depending on the species used to construct the algorithm. This small difference is not expected to contribute to the variability of the EC50 values found in experimental data.
pH:
Test results were taken from studies with measured pHs between 6 - 9.
Dissolved oxygen:
The dissolved oxygen concentration was more than 60% of the air-saturation value throughout the duration of the test. In exceptional cases where studies with oxygen concentrations lower than 60% were used, all aspects of the study were thoroughly evaluated in order to satisfy the evaluator that the effects found were not due to reduced oxygen concentration
Salinity:
Not specified
Conductivity:
Not specified
Nominal and measured concentrations:
Not applicable
Details on test conditions:
Preferentially results from semi-static studies were used. However, substances tested using a static design were accepted (preferably accompanied by analytical measurements over the study period). For suspected volatile substances only tests performed in closed vessels were accepted unless accompanying analytical monitoring proved such a design was not necessary.
Reference substance (positive control):
not required
Remarks:
QSAR model
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
73 mg/L
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL [51 - 103 mg/L]
Details on results:
None
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
95 % CL [51 - 103 mg/L] QSAR statistical parameters are given in the QMRF and QPRF

None

Validity criteria fulfilled:
yes
Remarks:
The substance falls into applicability domains of the model QSAR
Conclusions:
48 h EC50 for dimethyl pimelate = 73 mg test item/L with 95 %-Confidence Limit of 51 - 103 mg test item/L.
Executive summary:

A Quantitative Structure-Activity Relationship (QSAR) model was used to calculate the acute toxicity of the test item dimethyl pimelate to daphnid. 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. 202, "Daphniasp., Acute Immobilisation Test", referenced as Method C.2 of Commission Regulation No. 440/2008. The criterion predicted was the EC50 (Median Effective Concentration), a statistically derived concentration which is expected to cause immobility in 50% of test animals within a period of 48 hours.

 

The immobility of the daphnids was determined using a validated QSAR model for the Mode of Action (MOA) in question (poly-esters). The regression based method used to achieve this has been fully validated following the OECD (2004) recommendations. The QSAR model is based on validated data for a training set of 8 chemicals derived from 48-hour test on daphnids, for which the concentrations of the test item had been determined by chemical analyses over the test period.

The result below is the acute toxicity value anticipated during a 48-hour EC50 study on daphnids based on measured concentrations.The 48-hour EC50 is calculated as follows:

 

Time (h)

EC50 (mg test item.L-1)

95% confidence limits (mg test item.L-1)

48

73

51 - 103

Description of key information

48 h EC50 for dimethyl pimelate = 73 mg test item/L with 95 %-Confidence Limit of 51 - 103 mg test item/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
73 mg/L

Additional information

For that endpoint, a Quantitative Structure-Activity Relationship (QSAR) model was used. The purpose of this QSAR model is to accurately predict the acute toxicity of the registered substance to daphnids as would be expected in a laboratory experiment following OECD Guideline 202, for specific, named modes of action, to provide a value that can effectively replace a 48-hour EC50 value from an experimental study. The regression based method used to achieve this has been fully validated following the OECD recommendations for QSAR modeling (OECD, 2004).

The criterion predicted was the EC50 (Median Effective Concentration), a statistically derived concentration which is expected to cause immobility in 50% of test animals within a period of 48 hours.

In this study, the immobility of the daphnids was determined using a 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 8 chemicals derived from 48-hour test on daphnids, 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 202 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 EC50 based on nominal values) were used only when sufficient justification for stability of the test item was determined.

To conclude, this 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.