N-phenyl-N-[(trichloromethyl)thio]benzenesulphonamide

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-10-30 till 2013-01-28

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study without restrictions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(2006)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

(2009)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

N-phenyl-N-[(trichloromethyl)thio]benzenesulphonamide

EC Number:

218-915-0

EC Name:

N-phenyl-N-[(trichloromethyl)thio]benzenesulphonamide

Cas Number:

2280-49-1

Molecular formula:

C13H10Cl3NO2S2

IUPAC Name:

N-phenyl-N-[(trichloromethyl)sulfanyl]benzenesulfonamide

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Purity: 99.8 % N-Phenyl-N-[(trichloromethyl) thio]benzenesulphonamide, 0.1 % Benzenesulfonanilide (BSA) (Currenta study File No. 1106543101)
- Empirical formula: C13H10Cl3NO2S2
- Molecular mass: 382.7 g/mole

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Sampling schedule: Concentration of 100 mg/L was measured at 0 and 72 hours; and concentration of 0 mg/L at 72 hours only.
- Sample storage conditions before analysis: Routinely, the samples were analysed immediately. Only in exceptional cases, they were stored overnight deep frozen and protected from light.

Test solutions

Vehicle:

no

Details on test solutions:

Direct weighings were prepared to give the desired test item concentrations. To archive this test item concentrations 250.0, 500.4 and 1000.6 mg of the test item were weighed out and were given into 50 mL glass beakers. To the test item 5 mL of dilution water and 1272 μL of acetonitrile (Merck, density 0.786 g/mL) were added and the solution was stirred for 1 hour on a magnetic stirrer. Afterwards 600 μL of this solution were taken and made up with dilution water to the mark in a 1000 mL volumetric flask. The solution was stirred again for 1 hour on a magnetic stirrer. Finally undissolved particles of the test item were removed by filtration using a folded filter with a pore size of 7-12 μm. The pH was measured to be 7.8.

To produce the different test item concentrations filtered of each solution was taken 100 mL and 0.410 mL of the algal inoculum was added to each replicate resulting in a final cell density of 5000 cells/mL. For each test item concentration and the control 3 replicates were prepared. All flasks were sealed with cotton stoppers.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

- Name : Desmodesmus subspicatus (formerly Scene-desmus subspicatus) Strain No. 86.81 SAG
- Source : Strain of the test species obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen (Germany).
- Maintenance and Acclimatisation : Exponentially growing stock cultures were maintained in the test facility under constant temperature conditions (21-24 °C with a maximum fluctuation of +/- 2 °C) at a light intensity in the range 60 to 120 μE x m-2 x s-1 (measured in the range 400 to 700 nm using a spherical quantum flux meter). The growth medium (according to BRINGMANN & KÜHN (1977) was renewed once a week. Cell density measurements were made using a microcell counter, Sysmex F300, Digitana.
- Preparation of pre cultures : Pre cultures were set up three days before the start of a test. They were grown under identical exposure conditions as the stock cultures, except from the use of a different growth medium.
- Test cultures : The algal inocula for the test were taken from an exponentially growing pre culture and were mixed with the growth medium to make up to a final cell density of about 5000 cells per millilitre in the test medium.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

21 - 24 °C

pH:

Control: 7.9 at 0 h and 9.7 at 72 h
Solvent control: 7.9 at 0 h and 9.6 at 72 h
Test concentrations: 25, 50 and 100 mg/L showed a pH value of 7.9 at 0 h and 9.7 - 9.9 at 72 h
The pH value in the both controls after 72 hours increased by more than
1.5 pH units. This increase is not regarded to be relevant to the results as all validity criteria were met.

Nominal and measured concentrations:

Concentrations of test item: 25, 50 and 100 mg/L plus control

Details on test conditions:

- Test vessels : 300 mL Erlenmeyer flasks with cotton stoppers, test volume: 100 mL
- Culturing apparatus : Shaking incubator in which a temperature in the range 21 °C to 24 °C was maintained at +/- 2 °C, and continuous uniform illumination was provided in the spectral range 400 to 700 nm. Temperature was measured and recorded daily.
- Light intensity : A light intensity ranging from 60 to 120 μE x m-2 x s-1, or an equivalent range of 4000 to 8000 lux, was measured. The light intensity was checked before the start of the study.
- Cell density measurements : Cell densities were measured in a microcell counter (Sysmex F300, Digitana) by taking small aliquots from each test flask, which were not replaced.
- Experimental design : 3 test concentrations plus 1 control, additionally 1 solvent control
3 replicates per concentration, 3 replicates per control and solvent control
Initial cell density in the test cultures approximately 5000 cells per millilitre. Additionally highest test concentration without algae.
- Test item concentration/s : 25, 50 and 100 mg/L
- Method of administration : direct weighing
- Duration of exposure: 72 hours
- Criteria of effects : The criteria of adverse effects used in this study were the item-induced inhibition of yield [y] and growth rate [r] of the algal population.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

other: ErC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

other: ErC10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

other: NOEC[r]

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

other: LOEC[r]

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Reduction of growth rate (ErCx, NOEC [r]) is the preferred endpoint according to OECD 201 and for regulatory purposes in the EU. Results relating to yield (EyCx, NOEC [y]) were calculated to fulfil regulatory requirements in some countries (but not in the EU) and are given in the results section of this report.

Any other information on results incl. tables

No toxic effects against Algae were observed at the limit of water solubility under exposure conditions.

The results are expressed in terms of nominal concentrations. Effective concentrations were below the determination limit of the analytical method (0.0194 mg/L) at 0, 24, 48 and 72 hours.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

(-The factor of biomass parameter 136.0 >16; - The mean of the replicate coefficients of variation in the section-by-section growth 26.6 % <35 %; - The coefficient of variation of the mean specific growth rate in the control 0.8 < 7 %)

Conclusions:

No toxic effects against algae were observed at the limit of water solubility under exposure conditions.

Executive summary:

In order to test acute toxicity to algae of the substance, Desmodesmus subspicatus was exposed to the test solution of three nominal concentration of the test substance (25, 50 and 100 mg/L) and blank control solution for a period of 72 hours under static conditions. The cell densities were measured at 24 hours intervals. Inhibition of the algal population was measured as reduction in growth rate (index r), relative to control cultures grown under identical conditions. The measured concentraions confirmed that deviation from the nominal concentrations was less than 30 %. No toxic effects against algae were observed at a limt test concentration of 100 mg/L. This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute algae study.