Pent-1-ene

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

from 2017-07-13 to 2017-07-17

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:

QSAR predictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Deviations:

not applicable

Remarks:

QSAR model

Principles of method if other than guideline:

The purpose of this QSAR model is to accurately predict the toxicity to microorganisms as would be expected in a laboratory experiment following OECD Guideline 209 (1) and EC method C.11 (2) for specific, named modes of action to provide a value that can effectively replace a 30 to 180 minutes EC50 value from an experimental study. The regression based method used to achieve this has been fully validated following the OECD (2004) (3) recommendations (refer to the QMRF with KREATiS QMRF identifier: KTS/QMRF/ASR/01 for further details).

GLP compliance:

no

Specific details on test material used for the study:

not applicable

Analytical monitoring:

no

Remarks:

all tests used in the training set were based on measured data or on convincing evidence theat the test concentration was stable in the study; The results of the QSAR are therefore equivalent to measured concentrations

Details on sampling:

not applicable

Details on test solutions:

not applicable

Test organisms (species):

other: This study is not performed on a single or known species as such. Results were acquired from studies where the following test system was used: Activated sludge collected and treated according to the method outlined in OECD 209

Test type:

other: QSAR

Remarks on exposure duration:

30-180 min (see below)

Post exposure observation period:

Results from a test duration of 30 to 180 minutes only were used for this algorithm. The data were separated into two groups (30 and 180 minutes) but the variability between results was not considered important enough to merit the production of two separate models. Thus 30-180 minute data were compiled.

Hardness:

The QSAR is based on data from studies performed at acceptable hardness to ensure control survival.

Test temperature:

The temperatures varied from approximately 20 to 25 °C depending on the studies 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 QSAR is based on data from studies performed at acceptable oxygen concentrations (generally >60%).

Salinity:

not applicable

Nominal and measured concentrations:

This study is typically performed using nominal concentrations. In the case where the test substance was highly volatile this could have caused bias and attempts were made to use measured values when these were available.

Details on test conditions:

Following OECD 209, all studies used 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 not necessary.

Reference substance (positive control):

no

Remarks:

QSAR model

Key result

Dose descriptor:

EC50

Effect conc.:

45 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: 95%CL: 30-67 mg/L

Details on results:

The predicated value is reliable since the test substance falls within the applicability domain of the model. The water solubility value of the test substance is within descriptor domain of the model between log water solubility (in log (mol/L)) of -4.63 to 0.87. Moreover the test substance is attributed to the class of non-polar narcotic compounds.

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

95% confidence interval (α = 0.05): 30 – 67 mg/L
Information about the statistical validity of the model is provided in the QMRF report KTS/QMRF/ASR/01.

No additional informations

Validity criteria fulfilled:

yes

Remarks:

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

Conclusions:

The 30-180min EC50 based on inhibition of respiration was determined to be 45 mg/L with 95%-Confidence Limit between 30 and 67 mg/L.

Executive summary:

A QSAR model was used to calculate the inhibition of respiration to activated sludge of the test item pent-1-ene. 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 Guideline for Testing of Chemicals No. 209, "Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation)" (1), referenced as Method C.11 of Commission Regulation No. 440/2008 (2). The criterion predicted was the 30 to 180 minutes EC50 (Median Effective Concentration for specific respiration rate), a statistically derived concentration which is expected to cause 50% inhibition of intrinsic rate of respiration of the test system within a period of 30 to 180 minutes as an effect on the organic carbon oxidation process. The results from this study do not include the supplementary test results that may be required to determine the effect on nitrification. It should be noted that a specific test duration time could not be determined for this model as 30 and 180 minute data were available but not in sufficient quantity to separate them into two separate models.

The respiration inhibition of activated sludge was determined using a validated QSAR model for the Mode of Action in question (MOA 1, non-polar narcosis). The QSAR model is based on validated data for a training set of 12 chemicals derived from 30-180 minute EC50 for which the concentrations of the test item had been determined by chemical analyses over the test period. Further valid data were available but the values were all above the water solubility of the substance and were therefore not included as part of the regression. On the other hand, these data could be used to determine the point at which the regression no longer holds true and results from experimental studies on this MOA are expected to be greater than the solubility limit (i.e. test substance concentrations up to 100 mg/L will result in no effect on activated sludge respiration).

The 30-180 min EC50 based on inhibition of respiration was determined to be 45 mg/L with 95%-Confidence Limit between 30 and 67 mg/L.

Description of key information

QSAR model, iSafeRat holistic approach v1.7, key study, validity 1:

30 -180min EC50 = 45 mg/L (95% CL: 30 - 67 mg/L).

Key value for chemical safety assessment

EC50 for microorganisms:

45 mg/L

Additional information

To assess the toxicity of the registered substance to microorganisms, one data point is available.

A QSAR model was used to calculate the inhibition of respiration to activated sludge of the test item pent-1-ene. 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 Guideline for Testing of Chemicals No. 209, "Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation)" (1), referenced as Method C.11 of Commission Regulation No. 440/2008 (2). The criterion predicted was the 30 to 180 minutes EC50 (Median Effective Concentration for specific respiration rate), a statistically derived concentration which is expected to cause 50% inhibition of intrinsic rate of respiration of the test system within a period of 30 to 180 minutes as an effect on the organic carbon oxidation process. The results from this study do not include the supplementary test results that may be required to determine the effect on nitrification. It should be noted that a specific test duration time could not be determined for this model as 30 and 180 minute data were available but not in sufficient quantity to separate them into two separate models.

The respiration inhibition of activated sludge was determined using a validated QSAR model for the Mode of Action in question (MOA 1, non-polar narcosis). The QSAR model is based on validated data for a training set of 12 chemicals derived from 30-180 minute EC50 for which the concentrations of the test item had been determined by chemical analyses over the test period. Further valid data were available but the values were all above the water solubility of the substance and were therefore not included as part of the regression. On the other hand, these data could be used to determine the point at which the regression no longer holds true and results from experimental studies on this MOA are expected to be greater than the solubility limit (i.e. test substance concentrations up to 100 mg/L will result in no effect on activated sludge respiration).

The 30-180 min EC50 based on inhibition of respiration was determined to be 45 mg/L with 95%-Confidence Limit between 30 and 67 mg/L.