2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonyl chloride

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:

2018-08-03 to 2018-09-28

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)

Version / remarks:

2011

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2016

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

HPLC-DAD

Details on sampling:

- Concentrations: Nominal: 250 mg/L and 0 mg/L
- Sampling method: The concentrations of 2H-lsoindole-2-ethanesulfonic acid, 1,3-dihydro-1,3-dioxo-, potassium salt (1:1) (TA-1) were determined in the fresh media (0 h) and old media (72 h) in the limit concentration and in the control via HPLC-DAD. The sample and the control were diluted (factor 2) with acetonitrile directly after sampling. Further dilution was made prior to analysis with dilution medium for the limit concentration.
- Sample storage conditions before analysis: All samples were stored at room temperature until the start of analysis, if necessary. Prepared samples were stored in an autosampler at room temperature until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solution = Limit concentration: 250 mg test item/L, freshly prepared with dilution water. The stock solution was agitated until the test item was completely dissolved.
- Controls: Six replicates (without test item) were exposed under the same conditions as the test item replicates. Reference item: Potassium dichromate was tested as a reference item
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): No, all solutions were visually clear.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: Pseudokirchneriella subcapitata HINDAK CCAP 278/4
- Age of inoculum (at test initiation): A four days old preculture, prepared in dilution water, was used as inoculum.
- Method of cultivation: Fresh stocks are prepared every month on Z-Agar. Light intensity amounts to 2567 - 5130 lux for 24 h per day.

ACCLIMATION
- Acclimation period: N/A
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: not reported

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

0.24 mmol Ca+Mg/L

Test temperature:

Nominal range: 21 - 24 °C, controlled at ± 2 °C

pH:

8.11 to 9.43

Nominal and measured concentrations:

Nominal: 250 mg/L and 0 mg/L
Geometric measured mean: 186 mg/L and < LOQ

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type: closed
- Material, size, headspace, fill volume: Total volume: 250 mL and fill volume: 100 mL
- Aeration: No, test containers were placed on a rotary shaker and oscillated at approximately 70 rpm.
- Initial cells density: 5E03-E04 cells/mL, (actual: 6442 cells/mL)
- No. of vessels per concentration (replicates): 6 replicates
- No. of vessels per control (replicates): 6 replicates

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Concentration [mg/L]
NH4Cl 15
MgClg x 6 H2O 12
CaCl2 x 2H2O 18
MgSO4 x 7 H2O 15
KH2PO4 1.6
FeCl3 x 6 H2O 0.064
Na2EDTA X 2 H2O 0.1
H3BO3 0.185
MnCl x4 H2O 0.415
ZnCl2 3E-03
Na2MoO4 x 2 H2O 7E-03
COCl2 x 6 H2O 1.5E-03
CuCl2 x 2 H2O 1E-05
NaHCO3 50
pH 8.1 ± 0.2
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 24 h/day light
- Light intensity and quality: Approximately 4440 to 8880 lux, corresponding to 60 to 120 pE*m-2*s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: fluorimeter
- Chlorophyll measurement:Chlorophyll a-fluorescence, excitation at 436 nm, emission at 685 nm
- Other: Microscopic evaluation of the cells at the start and the end of exposure was carried out. The cells were checked for unusual cell shapes, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algae cells.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: N/A
- Justification for using less concentrations than requested by guideline: Limit Test
- Range finding study: yes, including analysis of the nominal concentrations of 1.00, 10.0, 100 mg/L
- Test concentrations: 1.00, 10.0, 100 mg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: growth: 1.09 CI (0.842-1.31);
yield: 0.548 CI (0.439 - -0.660)

Reported statistics and error estimates:

Protesting
Shapiro-Wilk's Test on Normal Distribution:
Normality check was passed (Shapiro-Wilk's; p > 0.01).
Levene's Test on Variance Homogeneity:
Variance homogeneity check was passed (p > 0.01).
STUDENT-t test for Homogeneous Variances with growth rate at 0 - 72 h: Two-sample comparison of treatments with "Control". Significance was Alpha = 0.050. one-sided smaller; Mean: arithmetic mean; n: sample size; s: standard deviation; MDD: minimum detectable
difference to Control (in percent of Control); t: sample t; p(t): probability of sample t for Ho: p1 = p2; the differences are significant in case p(t) <= Alpha (The residual variance of an ANOVA was applied; df = N - k; N: sum of treatment replicates n(i); k: number of treatments).

Table 1: Nominal and measured concentrations for 72 h

Sampling date	0h		72h		Geometric mean measured test item concentration [mg/L]
Nominal test tiem conce3ntration [mg/L]	2H-lsoindole-2-ethanesulfonic acid, 1,3-dihydro-1,3-dioxo-, potassium salt (1:1) (TA1)
	Meas. Conc. [mg/L]	%	Meas. Conc. [mg/L]	%
250	275	110	126	50	186
Control	< LOQ		< LOQ		-

Meas. conc. = measured concentration of the test item, dilution factors taken into account

% = percentage of the nominal concentration of the test item

LOQ = limit of quantification of the analytical method (25.0 mg test item/L)

Validity criteria fulfilled:

yes

Conclusions:

In this study, 2H-isoindole-2-ethanesulfonic acid, 1,3-dihydro-1,3-dioxo-, potassium salt (1:1) (TA-1) did not inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 h. The EC50-values tor inhibition of growth rate (ErC50) and yield (EyC50) after 72 h were > 186 mg/L (all values based on geometric mean measured test item concentration). The NOEC-values for inhibition of growth rate and yield after 72 h were ≥ 186 mg/L, respectively.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
For detailed information please refer to the 'attached justification' section

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar biodegradation and ecotoxicological behaviour because the target substance, TA-2, exhibits the same core structure as TA-1 (source substance). TA-2 was investigated for stability in aqueous solutions by implementation of analytical methods via LC-MS/MS and LC-QToF employing ESI ionization. Based on observations resulting from these experiments, a complete hydrolysis of the test item within the mobile phase contact time (less than 1 minute for all experiments) can be assumed. This corresponds to the known reactivity (hydrolytically instability) of the sulfonyl chloride functional group of the target substance. Hydrolysis of 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonyl chloride (TA-2) results in its breakdown product 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid which is also considered to be the main constituent in aqueous solutions of the source substance 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid- potassium (TA-1) . Studies to determine biodegradation and aquatic ecotoxicity are conducted in water, thus, these studies use the hydrolysis product 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid as active ingredient. Testing of TA-2 in aqueous solutions is therefore assumed to reveal the same results as compared to TA-1.

2. SOURCE AND TARGET CHEMICAL(S)
The target substance, 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl) ethane-1-sulfonyl chloride contains Phthalimid as core structure linked to an ethansulfonyl chloride group. Furthermore, the target substance is hydrolytically not stable and is experimentally shown to rapidly degrade to 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid (source substance) and chloride.
The source substance 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid--potassium is a water soluble substance for which was shown to be stable in aqueous solutions (study according to OECD guideline 201). It consists of the same core structure as the target substance (Phthalimid with sulfonic acid as functional group). TA-1 as a solid contains potassium as counter ion but when used in aqueous solutions is considered to be present as free sulfonic acid form.

3. ANALOGUE APPROACH JUSTIFICATION
The read-across hypothesis is based on the assumption that 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl) ethane-1-sulfonyl chloride hydrolyses fast to 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid. The source substance 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid--potassium (TA-1) is considered to be present in the free sulfonic acid form when dissolved in aqueous solutions, thus, the tests on biodegradation and ecotoxicity are performed with the same compound regardless whether TA-1 or TA-2 is used. Furthermore, available physico-chemical data reveal similar properties for both substances supporting the read-across strategy.

4. DATA MATRIX
For detailed information please refer to the 'attached justification' section

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 186 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Validity criteria fulfilled:

yes

Conclusions:

In this study, 2H-isoindole-2-ethanesulfonic acid, 1,3-dihydro-1,3-dioxo-, potassium salt (1:1) (TA-1) did not inhibit the growth of the freshwater green alga Pseudokirchneriella subcapitata after 72 h. The EC50-values tor inhibition of growth rate (ErC50) and yield (EyC50) after 72 h were > 186 mg/L (all values based on geometric mean measured test item concentration). The NOEC-values for inhibition of growth rate and yield after 72 h were ≥ 186 mg/L, respectively.
The target substance 2 -(1,3 -dioxo-1,3 -dihydro-2H-isoindol-2 -yl)ethane-1 -sulfonyl chloride (TA-2) is hydrolytically not stable and is experimentally shown to rapidly degrade to 2 -(1,3-dioxo-1,3 -dihydro-2H-isoindol-2 -yl)ethane-1 -sulfonic acid and chloride. The source substance 2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethane-1-sulfonic acid--potassium (TA-1) is present in the free sulfonic acid form when dissolved in aqueous solutions, thus, the tests on biodegradation and ecotoxicity are performed with the same compound regardless whether TA-1 or TA-2 is used. Therefore, the results for the source substance apply likewise to the target substance.

Description of key information

For 2 -(1,3 -dioxo-1,3 -dihydro-2H-isoindol-2 -yl)ethane-1 -sulfonyl chloride (TA-2) no experimental study on toxicity to aquatic algae and cyanobacteria is available.

The target substance 2 -(1,3 -dioxo-1,3 -dihydro-2H-isoindol-2 -yl)ethane-1 -sulfonyl chloride (TA-2) is hydrolytically not stable and is experimentally shown to rapidly degrade to 2 -(1,3 -dioxo-1,3 -dihydro-2H-isoindol-2 -yl)ethane-1 -sulfonic acid and chloride. The source substance 2 -(1,3 -dioxo-1,3 -dihydro-2H-isoindol-2 -yl)ethane-1 -sulfonic acid--potassium (TA-1) is present in the free sulfonic acid form when dissolved in aqueous solutions, thus, the tests on biodegradation and ecotoxicity are performed with the same compound regardless whether TA-1 or TA-2 is used. Therefore, the results for the source substance apply likewise to the target substance.

In a 72h-toxicity study to aquatic algae according to OECD guideline 201 (2011) with Pseudokirchneriella subcapitata at a nominal concentration of 250 mg/l (geometric mean measured concentration186 mg/L) 2 -(1,3 -dioxo-1,3 -dihydro-2H-isoindol-2 -yl)ethane-1 -sulfonic acid--potassium (TA-1) showed no toxicty (NOEC and EC50 based on algal growth were > 186 mg/L based on geo. mean measured concentrations).

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

186 mg/L