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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:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

From December 7, 2012 to February 15, 2013

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Remarks:

This study was performed according to OECD Guideline 201 with GLP certificate. All validity criteria were fulfilled. However, this study is considered not assignable due to insufficient information provided on the semi-static methodology used. A validation study should be provided to validate this method and, at the time being, a semi-static system is not accepted as an adaptation of the OECD Guideline. With this method, parent and degradation products are present simultaneously, so interactions can occured. In addition, acetone was used as solvent in this study. Because of the potential for interaction with the test chemical resulting in an altered response in the test, solvent use should be restricted to situations where no other acceptable method of test solution preparation is available. The use of solvent is not the best method at the time being. In addition, the concentration/quantity of solvent used in the treatment solutions was 0.5 mL/L, corresponding to 395 mg/L (with a density of 0.79), which is 5 times higher than the recommended maximum level of solvent (below 0.1 mL/L; OECD No. 23) but is below the NOEC of acetone (which was reported in the ECHA disseminated dossier at 530 mg/L). Finally, the 72h-ErC50 calculated is an extrapolated value, which is above the water solubility of this substance.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

March 2006

Deviations:

yes

Remarks:

Semi-static design not clearly explained; solvent used falsifying measurement of exposure values at each solution replacement; only 3 replicates in control. Extrapolated value above solubility to reach EC50.

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificate signed on January 10, 2013

Specific details on test material used for the study:

- Physical state: white crystalline powder
- Storage condition: Room temperature protected from direct sun light

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

acetone

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The treatment solutions were prepared in acetone. The different treatment solutions are shown in Table 6.1.5/1 in "Any other information on materials and methods including tables".
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): 0.5 mL/L. see Table 6.1.5/1

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: No.72
- Source (laboratory, culture collection): Museum d'histoire naturelle (Paris,France).
- Method of cultivation: the inoculum culture was prepared 2-4 days before the start of the test and incubated under the same conditions as the test cultures

ACCLIMATION
- Culturing media and conditions (same as test or not): the inoculum culture was prepared 2-4 days before the start of the test and incubated under the same conditions as the test cultures such to adapt the test algae to test conditions and ensure that the algae were in the exponential growth phase when used to inoculate the test solutions.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21 - 24°C +/- 2 °C

pH:

from 7.9 to 9.1
The initial pH value was within the range 8.6-8.8 for the controls and every test item treatments at test initiation. At the end of the test the pH value of the test media was similar to that of the controls for the three lowest test item treatments. At both 4.8 and 8.0 mg/L decrease of the final pH value suggested that growth was reduced.

Nominal and measured concentrations:

Definitive test : 1.0 - 1.8 - 2.9 - 4.8 and 8.3 mg/L (nominal)
Due to the high instability of the test item in water, it was anticipated that the test item treatments will not remain within 80-120 % of the nominal values. As a consequence, the test item treatments were set at 120% of the nominal values (1.2, 2.1, 3.5, 5.9 and 10.0 mg/L for 1.0, 1.7, 2.9, 4.9 and 8.3 mg/L) and further adjusted twice per day. Mean exposure concentrations were further calculated as the geometric mean of the measured concentrations in the old and new media throughout the test period (1.0, 1.8, 2.9, 4.8 and 8.0 mg/L).

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass Erlenmeyer flasks of 250 mL capacity
- Type (delete if not applicable): closed : the test vessels were capped with air-permeable stoppers
- Material, size, headspace, fill volume: flasks filled with 100 mL of culture
- Renewal rate of test solution (frequency/flow rate): Due to the high instability of the test item in water, it was anticipated that the test item treatments will not remain within 80-120 % of the nominal values. As a consequence, the test item treatments were set at 120% of the nominal values (1.2, 2.1, 3.5, 5.9 and 10.0 mg/L for 1.0, 1.7, 2.9, 4.9 and 8.3 mg/L) and further adjusted twice per day. Mean exposure concentrations were further calculated as the geometric mean of the measured concentrations in the old and new media throughout the test period.
- Initial cells density: The initial biomass in the test cultures was the same in all test ultures and sufficiently low to allow exponential growth throughout the incubation period without any risk of nutrient depletion. Historical data at Phytosafe site show that 2 to 5 x 10^3 cells/mL is an appropriate number.

- No. of vessels per concentration (replicates): 3 replicates for each the five test item treatments
- No. of vessels per control (replicates): 3 replicate units for the water control, for the solvent control and for each of five test item treatments

GROWTH MEDIUM
- Standard medium used: yes, OECD medium (OECD TG 201, according to ISO 8692) was freshly reconstituted by dilution of mineral stock solutions in pure water.

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Photoperiod: continuous uniform fluorescent illumination
- Light intensity and quality: 60-120 µE.m^-2.s^-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : The cell density was counted at test initiation and then after 24h, 48h and 72h of culture; growth rate and yield were evaluated.
- Determination of cell concentrations: electronic cell counter (cells/L of solution)

TEST CONCENTRATIONS
- Range finding study : yes
- Test concentrations: 0.01, 0.1, 1.0 and 10.0 mg/L
- Results used to determine the conditions for the definitive study: No adverse effects were observed in the solvent control and the test item treatments up to and including 1.0 mg/L. Both specific growth rate and yield reduced at 10 mg/L.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

10 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 10 mg/L is an extrapolated value > to solubility limit, based on geometric mean of measured concentrations

Remarks:

95% CI = 1.9 - 52.4 mg/L

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.9 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: based on mean measured concentrations

Details on results:

The cells appeared healthy in the controls and the test item treatments. The growth was solely inhibited without any abnormal appearance.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50: EC50 for specific growth rate between 0.6 and 1.0 mg/L
- Other: EC50 for yield between 0.2 and 0.75 mg/L

Reported statistics and error estimates:

F-variance analysis at a 5% confidence level was used to judge upon the difference for mean specific growth rate (section-by-section and total values) foe each test item treatment compared to the water controls.
For the entire test period, mean specific growth rate per day was considered as significantly reduced at 4.8 and 8.0 mg/L but similar to the controls for the solvent controls and the two lowest test item treatments (1.0 and 1.7 mg/L). At 2.9 mg/L mean growth rate per day was slightly increased : 1.70 instead of 1.67 for the water control, but 1.69 for the solvent control and the difference was not taken as a treatment induced effect.

Table 6.1.5/2: Mean measured concentrations of the test substance in the test item treatments and % of the nominal values

	Nominal concentrations, mg/L
	1.0	1.7	2.9	4.9	8.3
T0	1.21 119.5%	1.86 108.9%	3.32 114.6%	5.23 106.5%	9.22 110.7%
T0+7.5h - Old	1.07 106.0%	1.82 106.4%	3.03 104.5%	5.05 102.7%	7.92 95.1%
T0+7.5h - New	1.18 117.2%	1.91 111.9%	3.24 111.8%	5.38 109.5%	8.97 107.7%
T0+22.5h - Old	0.85 84.4%	1.51 88.1%	2.47 85.4%	4.25 86.5%	6.81 81.7%
T0+22.5h - New	1.09 108.2%	1.88 110.1%	3.24 111.9%	5.36 109.0%	8.96 107.6%
T0+31.5h - Old	0.93 92.0%	1.70 99.4%	2.68 92.3%	4.42 89.9%	7.38 88.6%
T0+31.5h - New	1.19 117.7%	2.12 124.1%	3.23 111.5%	5.58 113.5%	8.82 105.9%
T0+46.5h - Old	0.80 79.6%	1.46 85.6%	2.43 83.9%	3.92 79.9%	6.52 78.3%
T0+46.5h - New	1.26 124.8%	2.17 126.8%	3.65 125.8%	5.84 119.0%	9.13 109.6%
T0+55.5h - Old	0.97 96.0%	1.73 101.1%	2.89 99.7%	4.73 96.2%	7.83 94.0%
T0+55.5h - New	1.24 123.2%	2.11 123.4%	3.46 119.5%	5.54 112.9%	9.90 118.8%
T0+72h	0.80 78.8%	1.33 77.5%	2.45 84.6%	3.85 78.4%	6.59 79.2%
Geometric mean	1.0 mg/L	1.8 mg/L	2.9 mg/L	4.8 mg/L	8.0 mg/L

Table 6.1.5/3: Definitive test - Measured specific growth rates per day (section-by-section and total)

	0 to 24h	24 to 48h	48 to 72h	Total period
Water control
Rep 1	1,38	1,86	1,74	1,66
Rep 2	1,32	1,92	1,8	1,68
Rep 3	1,5	1,82	1,65	1,66
Mean +/- S.D.	1,40 +/- 0,09	1,87 +/- 0,05	1,73 +/- 0,08	1,67 +/- 0,01
Solvent control
Rep 1	1,32	1,8	1,9	1,67
Rep 2	1,5	1,74	1,87	1,7
Rep 3	1,53	1,8	1,73	1,68
Mean +/- S.D.	1,45 +/-0,11	1,78 +/- 0,03	1,83 +/- 0,09	1,69 +/- 0,02
Ambramone 1,0 mg/L
Rep 1	1,53	1,85	1,76	1,72
Rep 2	1,49	1,74	1,87	1,7
Rep 3	1,34	1,76	1,93	1,68
Mean +/- S.D.	1,45 +/- 0,10	1,78 +/- 0,06	1,88 +/-0,10	1,71 +/- 0,03
Ambramone 1,8 mg/L
Rep 1	1,58	1,9	1,51	1,67
Rep 2	1,52	1,83	1,68	1,68
Rep 3	1,52	1,92	1,65	1,7
Mean +/- S.D.	1,55 +/- 0,03	1,86 +/- 0,05	1,61 +/- 0,09	1,68 +/- 0,02
Ambramone 2,9 mg/L
Rep 1	1,59	1,82	1,66	1,69
Rep 2	1,57	1,92	1,61	1,47
Rep 3	1,66	1,83	1,62	1,32
Mean +/- S.D.	1,61 +/- 0,08	1,86 +/- 0,05	1,63 +/- 0,03	1,42 +/- 0,09
Ambramone 4,8 mg/L
Rep 1	1,58	1,65	1,15	1,46
Rep 2	1,56	1,72	1,14	1,47
Rep 3	1,7	1,43	0,82	1,32
Mean +/- S.D.	1,61 +/- 0,08	1,60 +/- 0,15	1,04 +/- 0,19	1,42 +/- 0,09
Ambramone 8,0 mg/L
Rep 1	1,37	0,6	0,71	0,89
Rep 2	1,4	1,5	0,25	1,05
Rep 3	1,39	1,19	0,4	0,99
Mean +/- S.D.	1,38 +/- 0,02	1,10 +/- 0,45	0,45 +/- 0,23	0,98 +/- 0,08

Table 6.1.5/4 : Definitive test - Percentages inhibition of specific growth rates per day (section-by-section and total

	0 to 24h (%)	24 to 48h   (%)	48 to 72h   (%)	Total period   (%)
Solvent control	-3,3	4,7	-5,9	-1,2
Ambramone
1,0 mg/L	-3,4	4,5	-8,8	-2,3
1,8 mg/L	-10,3	-1	6,7	-0,9
2,9 mg/L	-14,5	0,6	5,7	-1,9
4,8 mg/L	-15	14,3	40	15
8,0 mg/L	1,3	41,4	73,9	41,3

Negative values indicate that the growth rate was increased as compared to the controls.

Validity criteria fulfilled:

yes

Conclusions:

Based on specific growth rate, the 72h-NOEC and 72h-ErC50 values were determined at 2.9 and 10 mg/L (extrapolated value; 95% Ci 1.9-52.4 mg/L), based on geometric mean measured concentrations.
This study is considered not assignable due to insufficient information provided on the semi-static methodology used.

Executive summary:

This study was performed to assess the effect of the tested item on the growth of Desmodesmus subspicatus. The method followed that described in the OECD Guideline No. 201.

Following a preliminary range-finding study, Desmodesmus subspicatus was exposed to the test material (prepared with acetone as solvent) at concentrations of 1.0 - 1.7 - 2.9 - 4.9 and 8.3 mg/L (nominal) for 72 hours, under continuous uniform fluorescent illumination at a temperature of 21 -24 +/- 2°C °C.

Due to high volatility of the test item, the test item treatments were not maintained within 80-120% of the nominal value during the test period even though the test item treatments were set at 120% of the nominal values and the treatments were adjusted twice per day. The calculations were based on the geometric mean of the measured concentrations during the test period in the old and the new media (1.0 - 1.8 - 2.9 - 4.8 - 8.0 mg/L).

Exposure of Desmodesmus subspicatus to the test material gave ErC50 value of 10 mg/L (extrapolated value) [95% CI = 1.9 - 52.4 mg/L] and correspondingly the NOEC was 2.9 mg/L, based on specific growth rate.

All validity criteria were fulfilled. However, this study is considered not assignable due to insufficient information provided on the semi-static methodology used. A validation study should be provided to validate this method and, at the time being, a semi-static system is not accepted as an adaptation of the OECD Guideline. With this method, parent and degradation products are present simultaneously, so interactions can occured. In addition, acetone was used as solvent in this study. Because of the potential for interaction with the test chemical resulting in an altered response in the test, solvent use should be restricted to situations where no other acceptable method of test solution preparation is available.  The use of solvent is not the best method at the time being. In addition, the concentration/quantity of solvent used in the treatment solutions was 0.5 mL/L, corresponding to 395 mg/L (with a density of 0.79), which is 5 times higher than the recommended maximum level of solvent (below 0.1 mL/L; OECD No. 23) but is below the NOEC of acetone (which was reported in the ECHA disseminated dossier at 530 mg/L). Finally, the 72h-ErC50 calculated is an extrapolated value, which is above the water solubility of this substance.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

October 1st, 2019

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:

1. SOFTWARE
iSafeRat® holistic HA-QSAR v1.8

2. MODEL (incl. version number)
iSafeRat® High-Accuracy-Quantitative Structure-Activity Relationship (HA-QSAR) based on a holistic approach for predicting physicochemical and ecotoxicological endpoints: Short-term toxicity to algae (inhibition of the exponential growth rate)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
CC1(C)C2(C3)C(C(C3(CCC)CC2)=O)CCC1

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QPRF

6. ADEQUACY OF THE RESULT
See attached QPRF

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

not applicable

Remarks:

QSAR model

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

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 algae as would be expected in a laboratory experiment following the OECD Guideline 201 and EC method C.3 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 is method used to achieve this has been fully validated following the OECD (2004) recommendations (refer to the QMRF with JRC/KREATiS QMRF identifier: Q19-46-51-448 for further details).

GLP compliance:

no

Specific details on test material used for the study:

- Mechanism of action : MechoA 1.1: non-polar narcosis (Bauer et al., 2018)
- Melting point: 46.1°C (Phytosafe, 2012; EU Method A.1; DSC Method)
- Water solubility : 5.4 mg/L (Phytosafe, 2012; EU Method A.6; Column Elution Method)

Analytical monitoring:

not required

Details on sampling:

Not applicable

Vehicle:

no

Details on test solutions:

Not applicable

Test organisms (species):

other: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda

Details on test organisms:

Results from the following species were used in the regression: Pseudokirchneriella subcapitata, Desmodesmus subspicatus, Scenedesmus quadricauda.
No difference in relationship between solubility and ecotoxicity between algae (or indeed other) aquatic species is expected. Any observed differences may be attributed to lifestyle related parameters and relative duration of study versus bodysize rather than to a specific toxic mechanism causing species differences.

Test type:

other:

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Remarks on exposure duration:

None

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 specified

Salinity:

Not applicable

Conductivity:

Not applicable

Nominal and measured concentrations:

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 ErC50 based on nominal values) were used only when sufficient justification for stability of the test item was determined.

Details on test conditions:

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.

Reference substance (positive control):

no

Remarks:

QSAR model

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.6 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI: 0.80 – 8.8 mg/L

Details on results:

The Subcooled Liquid Water Solubilityvalue (determined at 8.76 mg/L or -4.427 in log (mol/L)) given as the input to the Ecotox module of the iSafeRat® Holistic HA-QSAR falls within the intermediate domain of the model between a log water solubility (in log (mol/L)) of - 9.34 to - 4.38.
The test substance is attributed to the class of non-polar narcotic compounds (MechoA 1.1).

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

95% CI: 0.80 – 8.8 mg/L.
QSAR statistical parameters are given in the QMRF and the QPRF, see the attached background material.

No additional information

Validity criteria fulfilled:

yes

Remarks:

The substance falls into applicability domain of the QSAR model.

Conclusions:

The 72-h ErC50 based on measured concentrations was determined to be 2.6 mg/L with 95%-Confidence Interval between 0.80 and 8.8 mg/L.

Executive summary:

A QSAR prediction (KREATiS, 2019) was performed to assess the inhibition of growth to algae of the test substance. This QSAR has been validated to be compliant with the OECD recommendations for QSAR modelling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guideline 201. 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 a validated QSAR for the Mechanism of Action (MechoA) 1.1, non-polar narcosis. This QSAR is based on validated data for a training set of 40 chemicals derived from 72 -hour ErC50 test on algae, for which the concentrations of the test substance had been determined by chemical analyses over the test period. The Subcooled Liquid Water Solubilityvalue (determined at 8.76 mg/L or -4.427 in log (mol/L)) given as the input to the Ecotox module of the iSafeRat® Holistic HA-QSAR falls within the intermediate domain of the model between a log water solubility (in log (mol/L)) of - 9.34 to - 4.38 as demonstrated in the QPRF.

The 72-h ErC50 based on measured concentrations was determined to be 2.6 mg/L with 95%-Confidence Interval between 0.80 and 8.8 mg/L.

Description of key information

iSafeRat® High-Accuracy-Quantitative Structure-Activity Relationship, KREATIS, 2019 :

72h-ErC50 = 2.6 mg/L (95% confidence interval: 0.80 – 8.8 mg/L)

Key value for chemical safety assessment

EC50 for freshwater algae:

2.6 mg/L

Additional information

One experimental study and one QSAR prediction are available to assess the toxicity of the registered substance to aquatic algae.

The experimental study (Phytosafe, 2013) was considered as not assignable due to insufficient information provided on the semi-static methodology used. A validation study should be provided to validate this method and, at the time being, a semi-static system is not accepted as an adaptation of the OECD Guideline 201. With this method, parent and degradation products are present simultaneously, so interactions can occur. In addition, acetone was used as solvent in this study. Because of the potential for interaction with the test chemical resulting in an altered response in the test, solvent use should be restricted to situations where no other acceptable method of test solution preparation is available. The use of solvent is not the best method at the time being. In addition, the concentration/quantity of solvent used in the treatment solutions was 0.5 mL/L, corresponding to 395 mg/L (with a density of 0.79), which is 5 times higher than the recommended maximum level of solvent (below 0.1 mL/L; OECD No. 23) but is below the NOEC of acetone (which was reported in the ECHA disseminated dossier at 530 mg/L).

Under the test conditions, the 72h-ErC50 and NOEC values of the test substance to Desmodesmus subspicatus, based on growth rate, were determined at 10.0 mg/L (extrapolated value) and 2.9 mg/L, respectively, based on geometric mean measured concentrations. Due to high instability of the test substance in water, it was not possible to maintain the test concentration within 80 -120% of the nominal values, even though the test item treatments were set at 120% of the nominal values and the concentrations were adjusted twice per day. The 72h-ErC50 value is an extrapolated value, which is above the water solubility of the test substance. Based on all these deviations, these results cannot be used and the study was disregarded.

The QSAR prediction (KREATiS, 2019) was considered as reliable and was used as key data. The 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 OECD Guideline 201. The growth inhibition of algae was determined using validated QSAR model for the Mechanism of Action (MechoA) in question (MechoA 1.1, i.e. non-polar narcosis) (Bauer et al., 2018). The QSAR model is based on validated data for a training set of 40 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 result below is the toxicity values anticipated during a 72-hour study on algae based on measured concentrations. Therefore, this endpoint value can be considered valid for use in risk assessment and classification and labelling.

The 72h-ErC50 of the registered substance to algae was predicted at 2.6 mg/L (95% CI: 0.80 – 8.8 mg/L)