Bis(5-oxo-L-prolinato-N1,O2)zinc

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:

key study

Study period:

02 August 2016 to 20 January 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: YAKUSHOKHATSU No. 1121002, SEIKYOKU No.2 and KANPOKIHATSU No. 021121002

Version / remarks:

partially amended 2006 as the joint ordinance of The Japanese Ministry of Economy Trade and Industry (METI), Ministry of Health, Labour and Welfare (MHLW) and Ministry of the Environment (MOE).

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: JMAFF 2-7-7

Version / remarks:

The guidelines related to the study reports for the registration application of pesticide (Ref. No. 12-Nousan-8147 on 24 November 2000) & Ref. No.13-Seisan-3986 on 10 October 2001.

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

not specified

Vehicle:

not specified

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test solutions used in the test will be prepared prior to treatment according to its water solubility: by mechanical dispersion (using ultrasonic bath if it is needed) or by a method according to the Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, OECD No. 23.
The test solutions were prepared just before introduction of the algae (start of the experiment).

Test organisms (species):

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

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Nominal and measured concentrations:

Preliminary range-finding test 1 and 2: 0.1, 1.0, 10 and 100 mg/L.

Details on test conditions:

GROWTH MEDIUM
- Standard medium used: Yes. Reconstituted algal growth medium (OECD medium, according to OECD 201) was used as dilution water in the experiment.

TEST CONCENTRATIONS
- Range finding study
A preliminary range-finding test was conducted to determine the approximate toxicity of the test material so that appropriate test concentrations can be selected for use in the definitive test. Algal cells were exposed to each widely spaced concentration (factor e.g. 10) of the test material plus a control, for 72 hours.
Due to the high significant inhibition noted during the first preliminary range-finding test, furthermore problems observed during the analytical method development at lower test concentrations a second preliminary test was also conducted to try to find solution how to measure test material concentrations at these levels.
The second preliminary test was performed by taken into account that test material contains zinc, and thus there was a possibility that zinc is bound by EDTA into a complex. Therefore the second preliminary test was performed using EDTA-free medium to try to prevent bonding of zinc by EDTA into a complex and make the test material measurable.
- Test concentrations: Preliminary range-finding test 1 and 2: 0.1, 1.0, 10 and 100 mg/L.
- Results used to determine the conditions for the definitive study: Due to high significant inhibition observed during the preliminary tests, very low test material concentrations would need to be tested in the definitive test.
If the bonding of zinc by EDTA into a complex could be prevented to allow test material measurement, very low test material concentrations need to be tested. Also, the concentrations will decrease during the experiment and are expected to be lost by the end of the test. Finding a suitable analytical method for samples to achieve measureable test concentrations is very difficult.
Due to the problems detailed above and discussion with the sponsor it was decided the study should be stopped.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate is tested at least twice a year to demonstrate satisfactory test conditions.

Remarks on result:

not determinable

Details on results:

Due to high significant inhibition observed during the preliminary tests it was decided the study should be stopped.

Results of the First Preliminary Range-Finding Test

 

Nominal concentrations [mg/L]	Untreated control	0.1	1	10	100
Average of cell number at 72 hours (x 10^4 cell/mL)	73.00	72.00	7.50	1.00	1.00
Growth rate (μ) (0–72 h)	0.0596	0.0594	0.0280	0.0000	0.0000
% inhibition of μ (0–72 h)	-	0.3	53.1	100.0	100.0

 

 

Results of the Second Preliminary Range-Finding Test

Nominal concentrations [mg/L]	Untreated control	0.1	1	10	100
Average of cell number at 72 hours (x 10^4 cell/mL)	72.00	40.00	5.50	1.00	1.00
Growth rate (μ) (0–72 h)	0.0594	0.0512	0.0236	0.0000	0.0000
% inhibition of μ (0–72 h)	-	13.8	60.2	100.0	100.0

 

Validity criteria fulfilled:

not specified

Conclusions:

Due to high significant inhibition observed during the preliminary tests, very low test material concentrations would need to be tested in the definitive test. the concentrations will decrease during the experiment and are expected to be lost by the end of the test. Finding a suitable analytical method for samples to achieve measureable test concentrations is very difficult.
It was therefore decided the study should be stopped.

Executive summary:

A preliminary range-finding test was conducted to determine the approximate toxicity of the test material so that appropriate test concentrations can be selected for use in the definitive test. Algal cells were exposed to each widely spaced concentration (factor e.g. 10) of the test material plus a control, for 72 hours.

Due to the high significant inhibition noted during the first preliminary range-finding test, furthermore problems observed during the analytical method development at lower test concentrations a second preliminary test was also conducted to try to find solution how to measure test material concentrations at these levels.

The second preliminary test was performed by taken into account that test material contains zinc, and thus there was a possibility that zinc is bound by EDTA into a complex. Therefore the second preliminary test was performed using EDTA-free medium to try to prevent bonding of zinc by EDTA into a complex and make the test material measurable. The test concentrations were 0.1, 1.0, 10 and 100 mg/L in both range-finding tests.

Due to high significant inhibition observed during the preliminary tests, very low test material concentrations would need to be tested in the definitive test.

If the bonding of zinc by EDTA into a complex could be prevented to allow test material measurement, very low test material concentrations need to be tested. Also, the concentrations will decrease during the experiment and are expected to be lost by the end of the test. Finding a suitable analytical method for samples to achieve measureable test concentrations is very difficult.

Due to the problems detailed above and discussion with the sponsor it was decided the study should be stopped.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

(Q)SAR

Adequacy of study:

supporting study

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 limited documentation / justification

Justification for type of information:

1. SOFTWARE
EPI Suite Version 4.1.1

2. MODEL
ECOSAR v1.11

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
SMILES : N1C(=O)CCC1C(=O)O
CAS No.: 015454-75-8

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
ECOSAR contains a library of class-based QSARs for predicting aquatic toxicity, overlaid with an expert decision tree for selecting the appropriate chemical class. ECOSAR Version 1.11 is programmed to identify 111 chemical classes and allows access to 704 QSARs for numerous endpoints and organisms.
The Quantitative Structure Activity Relationships (QSARs) presented in the program are used to predict the aquatic toxicity of chemicals based on their similarity of structure to chemicals for which the aquatic toxicity has been previously measured. Most QSAR calculations in the ECOSAR Class Program are based upon the octanol/water partition coefficient (Kow). ECOSAR estimates log Kow values using the US EPA's KOWWIN Program.
QSARs 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 estimated Kow into the regression equation and correcting the resultant value for the molecular weight of the compound.

ECOSAR Methods for Deriving Equations
- Traditional QSAR Development using Experimentally Measured Data
The QSARs in ECOSAR for both neutral organics and classes with excess toxicity are based on a linear mathematical relationship between the predicted log Kow values and the corresponding log of the measured toxicity values (mmol/L) for a suite of training set chemicals within each class of interest. The studies collected for the training set chemicals in ECOSAR undergo an extensive data validation step to ensure appropriateness for inclusion in the model. ECOSAR study criteria articulate that the toxicity should be measured at pH 7 (replicating environmental conditions), the total organic carbon content should not exceed 2 mg/L, the water hardness should be approximately 150 mg/L CaCO3, results should be adjusted to, or measured at, 100 % active ingredient, and flow-through measured is preferred over static nominal, etc. Data received or identified in the open literature which is not accompanied with full study details to confirm conditions are often not considered appropriate for model development. Therefore, many measured ecotoxicity data points can be found in the open literature which are not considered suitable for inclusion in the ECOSAR model.
When collecting studies for inclusion in the training sets, standard test species were preferred.

5. APPLICABILITY DOMAIN
Two chemical classes were identified in the test material; the equations and applicability domains of the three classes are given below:
- Amides
Green algae 96-h EC50 estimated toxicity: The green algae 96-h EC50 values used to develop this SAR were measured, and the octanol water partition coefficients (Kow) were calculated using the computer program, KOWWIN (Version 1.67). The SAR equation used to estimate toxicity is:
Log 96-h EC50 (mmol/L) = -0.6214 (log Kow) – 0.7843
The EC50 is in millimoles per litre (mM/L); N = 8 + 4; and the Coefficient of Determination (R2) = 0.2009. To convert the EC50 from mM/L to mg/L, multiply by the molecular weight of the compound.
Maximum Kow: 6.4
Maximum MW: 1000

- Neutral Organic
Green algae 96-h EC50 estimated toxicity: The green algae 96-h EC50 values used to develop this SAR were measured and the octanol water partition coefficients (Kow) were calculated using the computer program, KOWWIN (Version 1.67). The SAR equation used to estimate toxicity is:
Log 96-h EC50 (mmol/L) = -0.6922 log Kow + 0.9253
The EC50 is in millimoles per litre (mM/L); N = 41 + 9; and the Coefficient of Determination (R2) = 0.6782. To convert the EC50 from mM/L to mg/L, multiply by the molecular weight of the compound.
Maximum Kow: 6.4
Maximum MW: 1000


6. ADEQUACY OF THE RESULT
ECOSAR is a widely accepted and well validated QSAR program. There is currently a study underway to experimentally determine the acute toxicity of the test material to algae and the dossier will be updated with the results accordingly. In the meantime, the calculated value is considered to be acceptable for a screening assessment.

Qualifier:

according to guideline

Guideline:

other: REACH Guidance on QSARs R.6, May/July 2008

GLP compliance:

no

Remarks:

As no laboratory work took place, compliance with GLP is not required.

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

592.207 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

not specified

Remarks on result:

other: Amides - acid

Details on results:

Two results are available for the different chemical classes ECOSAR identified within the test material. The value for the amides class was the lowest and as such has been selected as key on a precautionary basis.

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test material to green algae was calculated to be 592.207 mg/L

Executive summary:

The acute toxicity of the test material was calculated using ECOSAR v1.1 (2012) 2000 U.S. Environmental Protection Agency. Given that the substance is an organic molecule within the Molecular Weight range and Log Kow range of the training set compounds, the prediction is considered to be acceptable.

The acute toxicity of the test material to green algae was calculated to be 592.207 mg/L.

Description of key information

Due to high significant inhibition observed during the preliminary tests, very low test material concentrations would need to be tested in the definitive test. The concentrations will decrease during the experiment and are expected to be lost by the end of the test. Finding a suitable analytical method for samples to achieve measureable test concentrations is very difficult.

It was therefore decided the study should be stopped.

The acute toxicity of the test material was calculated using ECOSAR v1.1 (2012) 2000 U.S. Environmental Protection Agency. The LD50 to green algae was calculated to be 2.918 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

592.207 mg/L

Additional information

A preliminary range-finding test was conducted to determine the approximate toxicity of the test material so that appropriate test concentrations can be selected for use in the definitive test. Algal cells were exposed to each widely spaced concentration (factor e.g. 10) of the test material plus a control, for 72 hours.

Due to the high significant inhibition noted during the first preliminary range-finding test, furthermore problems observed during the analytical method development at lower test concentrations a second preliminary test was also conducted to try to find solution how to measure test material concentrations at these levels.

The second preliminary test was performed by taken into account that test material contains zinc, and thus there was a possibility that zinc is bound by EDTA into a complex. Therefore the second preliminary test was performed using EDTA-free medium to try to prevent bonding of zinc by EDTA into a complex and make the test material measurable. The test concentrations were 0.1, 1.0, 10 and 100 mg/L in both range-finding tests.

Due to high significant inhibition observed during the preliminary tests, very low test material concentrations would need to be tested in the definitive test.

If the bonding of zinc by EDTA into a complex could be prevented to allow test material measurement, very low test material concentrations need to be tested. Also, the concentrations will decrease during the experiment and are expected to be lost by the end of the test. Finding a suitable analytical method for samples to achieve measureable test concentrations is very difficult.

Due to the problems detailed above and discussion with the sponsor it was decided the study should be stopped.

The acute toxicity of the test material was calculated using ECOSAR v1.1 (2012) 2000 U.S. Environmental Protection Agency. Given that the substance is an organic molecule within the Molecular Weight range and Log Kow range of the training set compounds, the prediction is considered to be acceptable.

The acute toxicity of the test material to green algae was calculated to be 592.207 mg/L.