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

Toxicity to aquatic plants other than algae

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 Jan - 04 Feb 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 221 (Lemna sp. Growth Inhibition Test)

Version / remarks:

(draft)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.4400 (Aquatic Plant Toxicity Test using Lemna spp. Tiers I & II))

Qualifier:

according to guideline

Guideline:

other: FIFRA Guideline 123-2

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Nominal concentrations: 0 (Control), 6.25, 12.5, 25.0, 50.0 and 100 mg a.i./L.
- Sampling method: Samples of AE 0001789 Technical test solutions, including controls, were taken on Day 0 (new solutions), Day 3 (new solutions) and on Day 7 (old solutions) to measure actual exposure concentrations of AE 0001789 Technical. On Days 0 and 3 the test solutions were prepared as uniform batches. On these days a 260 mL aliquot of the uniform test solution was poured into each of the labeled test vessels. Approximately 10 mL of the remaining, fresh prepared, test solution was then collected for analysis at each concentration. On Day 7, a portion of the old test solutions from all replicates within a test concentration was composited. Approximately 10 mL of the composite sample was collected for measured concentration analysis at each test level.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: All of the test solutions were prepared as 2 L uniform batches. The high concentration test solution (100 mg a.i./L) was prepared by adding approximately 0.206 g of the AE 0001789 (97.4% a.i.) technical to approximately 1000 mL of 20XAAP media in a 2-L volumetric flask. The flask was shaken vigorously for 1 minute, followed by 30 minutes of sonication. The flask was then brought to a volume of 2 L and allowed to stir overnight (approximately 16 hours). The following day the remaining test solutions (50.0, 25.0, 12.5 and 6.25 mg a.i./L) were prepared using a 50% serial dilution procedure from the high concentration. Each concentration was prepared by adding 1000 mL of the next higher concentration to a 2-L volumetric flask and then bringing it to volume (2 L) with 20XAAP media and inverting several times. The control solution consisted of 20XAAP media only. No solvent was used to prepare any of the test solutions. Solutions were prepared in similar fashion for the day 3 renewal.
- Test concentration separation factor: 2

Test organisms (species):

Lemna gibba

Details on test organisms:

TEST ORGANISM
- Common name: Duckweed
- Strain: Lemna gibba G3
- Source: own culture, originally optained from the United States Department of Agriculture Fruit Laboratory, Beltsville, Maryland on June 3, 2004 and from the University of Minnesota, St. Paul, Minnesota on October 30, 2003. The two cultures were combined to form a single culture which was maintained in the laboratory and used to initiate this study.
- Age of inoculum (at test initiation): not stated in report but the density of the Lemna used in the definitive study was documented to verify that the cultures were in log phase growth at test initiation.
- Method of cultivation: Lemna culture techniques were based on those described by ASTM (2004). The cultures were renewed at least once per week.

ACCLIMATION
- Acclimation period: 14 days

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Hardness:

soft water

Test temperature:

25 ± 2.0 °C

pH:

7.7 - 9.0

Dissolved oxygen:

-

Salinity:

-

Conductivity:

1491 - 1603 µmhos/cm (mean: 1541 µmhos/cm)

Nominal and measured concentrations:

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

Details on test conditions:

TEST SYSTEM
- Incubation chamber used: yes
- Test vessel:
- Material, size, headspace, fill volume: 650-ml borosilicate glass crystallization dishes filled with approximately 260-ml of test solution.
- Type of cover: terile, petri dish lids
- Renewal rate of test solution: on day 3
- No. of fronds per colony: 13
- 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: according to guideline
- Intervals of water quality measurement: on day 0, 3 and 7

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: No
- Photoperiod: 24 hours light
- Light intensity and quality: 500 ± 10% foot-candles (5.4 klux).

EFFECT PARAMETERS MEASURED: Growth was determined by frond counts on days 0, 3, 5 and 7.
- Determination of frond number: manual counting
- Determination of biomass: Dry weight (The plants from each replicate were dried at approximately 60 °C for at least 24 hours, transferred to a desiccator to cool to ambient temperature, and then weighed to determine the dry weight (± 0.1 mg).)
- Other: Phytotoxicity observations were performed to determine the health of the plants in each test vessel.

RANGE-FINDING STUDY
- Test concentrations: 0.1, 1.0, 10 and 100 mg a.i./L with a control
- Results used to determine the conditions for the definitive study: The result was an inhibition in frond number, compared to the control, of -10, 7, 4 and 37 percent for the 0.1, 1.0, 10 and 100 mg a.i./L test concentrations, respectively. Inhibition in growth as determined by day 7 frond dry weights was-7, 11, 5 and 22 percent for the 0.1, 1.0, 10 and 100 mg a.i./L test concentrations, respectively.

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

> 104 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

frond number

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

51.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

frond number

Results:

Test Object	Lemna gibba G3
Exposure	7-Day, static -renewal
7- day EyC50 - frond count	>104 mg a.i./L
7- day ErC50 - growth rate for frond numbers	>104 mg a.i./L
7- day ErC50 - cumulative biomass for frond numbers	>104 mg a.i./L
7- day EyC50- frond dry weight	>104 mg a.i./L
7- day ErC50 - growth rate for frond dry weight	>104mga.i./L
Lowest Concentration With an Effect (LOEC)	104 mg a.i./L (frond counts, and growth rate and cumulative biomass for frond counts)
Highest Concentration Without Toxic Effect (NOEC)	51.1 mg a.i./L (frond counts, and growth rate and cumulative biomass for frond counts)
	72.9 mga.i./L(frond counts, and growth rate and cumulative biomass for frond counts)
Toxic Threshold Effect Concentration, TEC (Geometric mean of NOEC and LOEC)

Observations: Fronds in all levels appeared normal as compared to the control.

Conclusion:

The NOEC and LOEC in the 7-day exposure of Lemna gibba G3 to AE 0001789 Technical were 51.1 and 104 mg a.i./L (mean measured) for the endpoints of frond counts, cumulative biomass and growth rate for frond counts, respectively. The EC50 for all endpoints measured was >104 mg a.i./L which was the highest concentration tested.

Table 1: Measured Test Concentrations of AE 0001789 Technical During the Exposure of Lemna gibba G3

Nominal Conc. (mg ai/L)	Day 0 Measured Conc. (mg a.i./L)	Day 0 Percent Nominal*	Day 3 (new) Measured Conc. (mg ai/L)	Day 3 (new) Percent Nominal*	Day 7 Measured Conc. (mg ai/L)	Day 7 Percent Nominal*	Mean Measured Conc. (mg ai/L)	Mean Measured Percent Nominal*
Control	<0.31	-	<0.31	-	<0.31	-	<0.31	-
6.25	6.21	99	6.19	99	5.62	90	6.01	96
12.5	12.4	99	12.5	100	11.0	88	12.0	96
25.0	25.0	100	24.8	99	22.8	91	24.2	97
50.0	52.7	105	52.3	105	48.4	97	51.1	102
100	104	104	102	102	105	105	104	104

LOQ = 0.31mga.i./L

* 'Percent Nominal' calculations were made using unrounded data. Manual calculations using rounded data may vary slightly.

 

 

Table 2: Validity criteria for OECD 221 (2006)

Criterion from the guideline	Outcome	Validity criterion fulfilled
The doubling time of frond number in the control must be less than 2.5 days (60 h), corresponding to approximately a seven-fold increase in seven days and an average specific growth rate of 0.275 d^-1.	The doubling time of frond number in the control group during the 168 hour test was 1.65 days or approximately 40 hours.	yes

 

Validity criteria fulfilled:

yes

Remarks:

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

Description of key information

NOEC (7 d): 51.1 mg a.i./L (arith. mean measured, Lemna gibba, OECD 221)

EC50 (7 d): >104 mg a.i./L (arith. mean measured, Lemna gibba, OECD 221)

Key value for chemical safety assessment

EC50 for freshwater plants:

104 mg/L

EC10 or NOEC for freshwater plants:

51.1 mg/L

Additional information

One study on the effects of the test substance to aquatic plants is available (M-251602-01-1). The study was conducted in accordance with the prevailing OECD testing guideline (OECD 221) under GLP conditions. Measured test concentrations were within 96 - 104% of nominal. Based on measured concentrations, the NOEC in the 7-day exposure of Lemna gibba to the test substance was 51.1 mg a.i./L, for frond number, biomass and growth rate for frond counts, respectively. The EC50 for all endpoints measured was >104 mg a.i./L (arith. mean measured) which was the highest concentration tested. Fronds in all levels appeared normal as compared to the control.