Benzamide, N-[[4-[(cyclopropylamino)carbonyl]phenyl]sulfonyl]-2-methoxy-

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 - 28 Jan 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(1984, 2004 draft)

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(1996 draft)

Qualifier:

according to guideline

Guideline:

other: FIFRA Guideline 123-2 (1982)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: The nominal concentrations were 0 (Control), 3.13, 6.25, 12.5, 25, 50, and 100 mg/L (ppm).
- Sampling method: Test solutions from two sampling intervals were received and analyzed on January 24 (Day 0), and January 28, 2005 (Day 4).

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: All of the test solutions were prepared as 1 L uniform batches. The high concentration test solution (100 mg/L) was prepared by adding 0.1026 g of the AE 0001789 (corrected for 97.4% a.i. purity) technical to approximately 300 ml of media in a 1 L volumetric flask. The flask was then brought to a volume of 1 L. It was found from past work that extended mixing would be needed to solubilize the 100 mg a.i./L test solution. Therefore, this solution was allowed to stir for at least 16 hours to facilitate adequate mixing. The remaining test solutions (50.0, 25.0, 12.5, 6.25 and 3.13 mg a.i./L) were prepared using a 50% serial dilution procedure from the high concentration. Each concentration was prepared by adding 500 ml of the next higher concentration to a 1 L volumetric flask containing approximately 300 ml of media. The solutions were then brought to volume (1 L) with media and inverted several times. The control solution consisted of media only. No solvent was used to prepare any of the test solutions.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source: the strain was obtained from an in-house culture (PS 276). The culture was obtained from The University of Texas at Austin (Austin, TX, USA).
- Age of inoculum: 96-hour old batch culture of Pseudokirchneriella subcapitata (in log phase growth)
- Method of cultivation: Algae culture techniques were based on those described by Stein (1973).

ACCLIMATION
- Culturing media and conditions: The batch culture was grown under test conditions in an environmental chamber at 24 ± 2.0°C, with 24 hour light photoperiod, and a light intensity of approximately 400 foot-candles (4.3 klux).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

soft water: 40 to 60 mg/L as CaCO3

Test temperature:

23.5 to 24.3°C

pH:

7.3 to 9.7

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 3.13, 6.25, 12.5, 25.0, 50.0 and 100 mg a.i./L.
Mean measured concentrations:

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: open
- Material, size, headspace, fill volume: 250 mL sterile borosilicate glass culture flasks filled with approximately 100 milliliters of test solution and capped with sterile inverted glass beakers.
- Initial cells density: 10^4 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: soft water, according to guideline

OTHER TEST CONDITIONS
- Photoperiod: 24 hours
- Light intensity and quality: An array of cool white fluorescent lights with a light intensity of approximately 4000 lux as measured by a Sper Scientific Light Meter.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: For each study day, density was determined in the three replicates at each test concentration using a model Zl Beckman Coulter® particle counter.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: yes
- Test concentrations: 0.1, 1.0, 10.0 and 100 mg a.i./L plus a control group
- Results used to determine the conditions for the definitive study: Growth was only affected at the 100 mg a.i./L level with an inhibition of 78% based on cell counts.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 99.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 99.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks:

and biomass

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 99.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 99.7 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control: yes

Observations:No physical abnormalities were observed in the controls or treatment groups during the study.

Table 1: Mean Measured Test Concentrations of AE 0001789 During the 96-hour Exposure of Pseudokirchneriella subcapitatato AE 0001789

Nominal Conc. (mg a.i./L)	Day 0 Measured Conc. (mg a.i./L)	Day 0 Percent (%) Nominal	Day 4 Measured Conc. (mg a.i./L)	Day 4 Percent (%) Nominal	Mean Measured Conc. (mg a. i./L)	Percent (%) Mean Measured Conc.
Control	<LOQ	-	<LOQ	-	-	-
3.13	3.17	101	3.04	97	3.10	99
6.25	6.32	101	6.09	97	6.20	99
12.5	12.5	100	12.2	98	12.4	99
25.0	25.0	100	24.6	98	24.8	99
50.0	53.9	108	51.5	103	52.7	105
100	100	100	99.3	99	99.7	100

LOQ = 0.31 mg a.i./L

 

 

Table 2: Validity criteria for OECD 201 (2006)

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	The biomass in the control cultures increased exponentially by a factor of approx. 67 within the 72-hour test period and 159 within the 96-hour period.	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3) in the control cultures was 27%.	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests withPseudokirchneriella subcapitataandDesmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures was 2%.	yes

 

Validity criteria fulfilled:

yes

Remarks:

See Table 2 in "Any other information on results incl. tables".

Description of key information

EC50 (72 h): >99.7 mg a.i./L (arith. mean measured, Pseudokirchneriella subcapitata, OECD 201)

 

NOEC (72 h): >99.7 mg a.i./L (arith. mean measured, Pseudokirchneriella subcapitata, OECD 201)

Key value for chemical safety assessment

EC50 for freshwater algae:

99.7 mg/L

EC10 or NOEC for freshwater algae:

99.7 mg/L

Additional information

One study on the effects of the test substance to algae is available (M-252015-01-1). The study was conducted in accordance with the prevailing OECD testing guideline (OECD 201) under GLP conditions. In a test system, the highest tested concentration was 100 mg/L; the measured concentrations were within the range of 99 to 105% of the nominal concentrations. Based on measured concentrations, the 96h EC50 (growth rate) in the green algae Pseudokirchneriella subcapitata was calculated to be >99.7 mg/L test item (>100 mg/L nominal). The NOEC and LOEC values were ≥99.7 mg a.i./L and >99.7 mg a.i./L, respectively. No abnormalities were observed in the controls or treatment groups during the study and the substance shows no effects to freshwater algae up to the highest test concentration of 100 mg a.i./L (nominal).