Ethylene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2009

Reliability:

2 (reliable with restrictions)

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:

QSAR prediction

Principles of method if other than guideline:

The Ecosar class program has been developed primarily for the evaluation of neutral organic compounds and organic classes with excess toxicity. The QSARs in the Ecosar program are developed for chemical classes based on measured test data that have been submitted by industry or they are developed by other sources for chemicals with similar structures, e.g., phenols. Using the measured aquatic toxicity values and estimated Kow values, regression equations can be developed for a class of chemicals. Toxicity values for new chemicals may then be calculated by inserting the Kow into the regression equation and correcting the resultant value for the molecular weight of the compound.

GLP compliance:

not specified

Remarks:

Not applicable

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Not applicable

Analytical monitoring:

not required

Details on sampling:

Not applicable

Details on test solutions:

Not applicable

Test organisms (species):

other: green algae

Details on test organisms:

Not applicable

Test type:

other: Not applicable

Water media type:

freshwater

Total exposure duration:

96 h

Post exposure observation period:

Not applicable

Hardness:

Not applicable

Test temperature:

Not applicable

pH:

Not applicable

Dissolved oxygen:

Not applicable

Salinity:

Not applicable

Conductivity:

N/A

Nominal and measured concentrations:

Not applicable

Details on test conditions:

Not applicable

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

30.327 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

not specified

Key result

Duration:

96 h

Dose descriptor:

other: ChV

Effect conc.:

7.07 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

calculated using the neutral organic QSAR. Data entered: log kow = 1.13, Melting point = -169.15°C, water solubility = 131 mg/l

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Not applicable

N/A

Validity criteria fulfilled:

not applicable

Remarks:

QSAR

Conclusions:

The predicted 96hr EC50 and ChV are 30.327mg/L and 7.07 mg/L respectively.

Executive summary:

The predicted 96hr EC50 and ChV are 30.327mg/L and 7.07 mg/L respectively. Due to the practical difficulties associated with the ecotoxicity testing of gases (i.e. maintaining exposure concentrations) the use of QSAR toxicity estimates is an appropriate alternative. The ECOSAR model is a reliable and appropriate QSAR model to apply to ethylene as it is based on a related chemical dataset that calculates the toxicity of neutral organic hydrocarbons whose mode of action is non-polar narcosis. The endpoint calculated here is therefore a reasonable estimate of its baseline toxicity.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2015

Reliability:

2 (reliable with restrictions)

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:

The target lipid model (TLM) is a framework that relates toxicity to the physicochemical properties of a nonpolar organic constituent. It is a well documented and peer reviewed model that is widely used across the petrochemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

Qualifier:

no guideline required

Principles of method if other than guideline:

The endpoints calculated are the LL50, EL50, and NOELR -
The narcosis target lipid model was developed to predict the toxicity of chemicals to aquatic organisms that act via narcosis. It is based on the hypothesis that target lipid is the site of toxic action within the organism, that octanol is the appropriate surrogate, and that target lipid has the same physical–chemical properties in all organisms.
The approach describes:
• The theory and how to predict the acute toxicity to these organisms;
• Development of an Acute to Chronic ratio [ACR] for only hydrocarbons and for 29 data points.

Specific details on test material used for the study:

N/A

Details on sampling:

N/A

Details on test solutions:

N/A

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

N/A

Remarks on exposure duration:

N/A

Post exposure observation period:

N/A

Hardness:

N/A

Test temperature:

N/A

pH:

N/A

Dissolved oxygen:

N/A

Salinity:

N/A

Conductivity:

N/A

Nominal and measured concentrations:

N/A

Details on test conditions:

N/A

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

119.325 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: Result from QSAR

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

22.859 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other:

Details on results:

N/A

Reported statistics and error estimates:

N/A

N/A

Conclusions:

The estimated EL50 for this substance is 119.325 mg/L and the NOELR was 22.859 mg/L.

Executive summary:

The aquatic toxicity of this substance was estimated using the Target Lipid Model based on methodologies described by Mcgrath et al. (2004). The estimated EL50 for this substance is 119.325 mg/L and the NOELR was 22.859 mg/L.

Description of key information

The QSAR model predicts a 96 hour EC50 value of 30.3 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

30.3 mg/L

EC10 or NOEC for freshwater algae:

7.07 mg/L

Additional information

The Mattock (1996) study is a GLP, near guideline proprietary experimental study; however there are limitations in the study due to loss of the test substance. Ethylene is a gas at standard temperature and pressure and it was technically difficult to maintain aqueous concentrations of the gas during the study. The reported 72 hour EC50 for Selenastrum capricornutum was 40.5 mg/L based on biomass and 72.2 mg/L based on growth rate. The 72 hour NOEC was 13.9 mg/L for both biomass and growth rate. The results are based on the mean measured concentrations, though the ErC50 should be treated with caution as it lies outside the measured concentration range. This study was conducted to GLP standards and followed standard guidelines with minor deviations and a large proportion of the ethylene was lost during the test. Due to this limitation the study was used as a supporting study.

The key study for the endpoint is a QSAR prediction using the ECOWIN v1 ECOSAR (Nabholz and Mayo-Bean 2009) model. This model predicts a 96-hour EC₅₀value of 30.3 mg/L and a ChV of 7.07 mg/L.

The aquatic toxicity of this substance was estimated using the Target Lipid Model based on methologies described by Mcgrath et al. (2015). The estimated LL50 for this substance is 119.325 mg/L and the NOELR was 22.859 mg/L.