1-[2-(2-chloroethoxy)phenylsulfonyl]-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)urea;triasulfuron (ISO)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 19 to 23 1990

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

EPA OPP 72-3 (Estuarine/Marine Fish, Mollusk, or Shrimp Acute Toxicity Test)

Deviations:

yes

Remarks:

The deviations were not regarded to affect the study results: Different nominal test concentrations used from the study protocol; A bit lower light intensity measured at the test solution surface.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples (10- 100 mL) of each test solution and the control were obtained at test initiation (0-hour) and termination (96-hour) from the approximate midpoint of each test vessel for analysis. Three quality control samples, formulated in test dilution water at CGA131036 concentration within the nominal test concentration range were prepared at each sampling interval and remained with the exposure solution samples throughout the analysis.

Vehicle:

no

Details on test solutions:

A stock solutions of 300 mg/L was prepared in a glass jar by adding 0.9614 g of test
item to 3.0 L of filtered water. The stock solution was stirred with a Tamco Lab mixer for approximately 2.75 hours. Following stirring, the stock solution was passed through a glass funnel containing filter floss to remove any insoluble CGA131036. Test solutions were prepared individually by adding the appropriate amount of stock solution to the appropriate amount of dilution water resulting in a 100 mL of the desired test concentration. One control vessel was established containing the same dilution water and maintained under the same conditions as the exposure concentrations but containing no CGA131036. The ambient air temperature in the laboratory was controlled in order to maintain test solution temperatures at 25±1℃. Test solutions were not aerated. The test vessels were covered with a plate throughout the test to minimize evaporation. The test was illuminated at an intensity of 40 footcandles at the solutions' surface. The photoperiod during the test was the same as in the culture area.

Test organisms (species):

Americamysis bahia (previous name: Mysidopsis bahia)

Details on test organisms:

TEST ORGANISM
- Common name: Mysid Shrimp
- Source: In-house culture
- Age at study initiation: ≤ 24 hours old
- Method of breeding: The mysid culture area received a regulated photoperiod of 16 hours of light and 8 hours darkness. Light at an intensity of 50-110 footcandles at the culture solution surfaces was provided by Durotext Vitalite fluorescent bulbs. Ambient air temperature in the culture area was controlled in order to maintain the culture solution temperatures at 25 ± 1°C.
FEEDING DURING TEST
- Food type: Brine shrimp nauplii
- Frequency: Daily

Test type:

static

Water media type:

saltwater

Limit test:

yes

Total exposure duration:

96 h

Test temperature:

25±1℃

pH:

7.9

Dissolved oxygen:

5.7 - 7.8 mg/L

Salinity:

32‰

Nominal and measured concentrations:

- Nominal concentrations: control, 24, 41, 66, 110, 180 and 300 mg/L.
- Mean measured concentrations day 0 - day 4: < 5.0/5.2, 18, 27, 46, 82, 85, and 220 mg/L, respectively.

Details on test conditions:

TEST SYSTEM
- Test vessel: 1.6 L glass bowls
- Type: Closed (covered with plate glass to minimize evaporation)
- Volume of solution: 1000 mL
- Aeration: No
- No. of organisms per vessel: 10
- No. of vessels per concentration: 2
- No. of vessels per control: 2
- Source: Natural seawater collected from the Cape Cod Canal, Bourne, Massachusetts.
- Pre-treatment: The seawater was filtered through a series of polypropylene core filters (20- and 5-μm) and an then recirculated within an epoxy-lined concrete reservoir prior to use. The filtered seawater was pumped to the laboratory under constant pressure throught PVC pipe, an acitivated carbon filter and a polypropylene heat exchanger system.
- Measurement of pH and dissolved oxygen: At 0, 24, 48, 72 and 96 hours in each treatment and c
ontrol solutions.
- Measurement of temperature and salinity: At 0, 24, 48, 72 and 96 hours in in each treatment and control solutions.
OTHER TEST CONDITIONS
- Photoperiod: 16 hours daily
- Light intensity: 50 - 100 footcandles at the solution surfaces
EFFECT PARAMETERS MEASURED
- The number of mortalities and biological observations were recorded for each replicate test solution at 0, 24, 48, 72 and 96 hours of exposure.
RANGE-FINDING TEST
- Test concentrations: A preliminary range-finding test was conducted at nominal test concentrations of 70, 42, 25, 15, 9.1 and 5.6 mg A.I/L. An additional preliminary study was done at 500, 25, and 2.5 mg A.I./L.
- Results used to determine the conditions for the definitive study: The results of the preliminary test indicated that the LC50 value was between 70 and 500 mg/L of the test substance. Thus, the definitive test was conducted at nominal concentrations of 24, 41, 66, 110, 180 and 300 mg/L.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

46 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mortality

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

140 mg/L

95% CI:

85 - 220

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mortality

Details on results:

An overview of the results is provided in Tables 2 - 3 in 'Any other information on results incl. tables'.
After 96 hours exposure, 0, 0, 0, 0, 10, 0 and 100% mortality was observed at mean measured
concentrations of 0 (blank control), 18, 27, 46, 82, 85 and 220 mg/L, respectively.

Reported statistics and error estimates:

LC50 value estimated by non-linear interpolation; 95% confidence interval calculated by binomial probability.

Table 2 concentrations tested, corresponding cumulative mortalities and observations made during the 96-hour static exposure

Mean measured concentration (mg A.I/L)	cumulative mortality (%)
	24-Hour	48-Hour	72-Hour	96-Hour
220	0	40a	100	100
85	0	0	0	0b
82	0	0	10	10
46	0	0	0	0
27	0	0	0	0
18	0	0	0	0
Control	0	0	0	0

a: All of the surviving mysids were observed to be lethargic

b: One of the surviving mysids was observed to be lethargic

Table 3 estimated LC50 values and NOEC concentration

Observation Period	confidential interval
	LC50 (mg A.I./L)	Lower (mg A.I./L)	Upper (mg A.I./L)
24-Houra	>220	-	-
48-Houra	>220	-	-
72-Hourb	140	85	220
96-Hourb	140	85	220
NOEC through 96 hours: 46 mg A.I./L

a: LC50 value empirically estimated to be greater than the highest concentration tested; 95% confidence interval could not be calculated.

b: LC50 value estimated by non-linear interpolation; 95% confidence interval calculated by binomial probability.

Validity criteria fulfilled:

not specified

Conclusions:

In a 96-h toxicity study on Mysid shrimp, conducted according to a standard guideline, the LC50 was determined to be 140 mg/L, based on mean measured concentrations.

Executive summary:

The toxicity of the test item on mysid shrimp (Mysidopsis bahia) was investigated in a static study which was conducted according to a standard guideline. The study was in compliance with GLP principles. Mysid shrimp (≤ 24 hours old) were exposed to the test substance at concentrations of 0 (blank control), 24, 42, 66, 110, 180, and 300 mg/L (mean measured concentrations:
<5.0/5.2, 18, 27, 46, 82, 85, and 220 mg/L, respectively) for 96 hours. Ten mysid shrimps were introduced into each of 2 replicate test vessels per treatment and control. To check the concentrations of the test item, water samples were taken at 0 and 96 hours and analysed by using HPLC. The test conditions were as follows: temperature 25±1 °C, pH 7.6 - 8.0, dissolved oxygen in a range of 80 - 111 % air saturation, salinity 32 ‰. The number of mortalities and biological observations were made after 24, 48, 72 and 96 hours of exposure.
After 96 hours exposure, 0,0, 0, 0, 10, 0 and 100% mortality was observed at mean measured concentrations of 0 (blank control), 18, 27, 46, 82, 85 and 220 mg/L, respectively. Based on the findings, the LC50 of the test item was determined to be 140 mg/L, based on mean measured concentrations. The NOEC was determined to be 46 mg/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 Dec 1983 to 15 Dec 1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: EPA-Guideline EG-1, 8/10/82

Deviations:

yes

Remarks:

See deviations from guideline in ‘Any other information on results incl. tables’

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals: The test substance was homogeneously distributed at all test concentrations, samples for analysis were taken after 0h and 48h exposure.
- Sample storage conditions before analysis: After sampling at - 20°C.

Vehicle:

yes

Remarks:

551 mg DMSO; 2 mg ARKOPAL N150 per L water in the concentration used for the highest test concentration

Details on test solutions:

Stock solution: 200g test item was dissolved in DMSO; 4000 mg ARKOPAL N150 and made up to 1000 mL with DMSO. Solution was adjusted to pH 7.8 with 0.25 mL NaOH 1N and diluted 1:2000 with water.
Test concentrations: Calculated amounts of stock solution to produce the desired test concentrations were given into the water and homogeneously distributed.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water fleas
- Strain: Straus 1820
- Age at study initiation: ≤ 24 hours old
- Source: The test facility
- Acclimation: None. Breeding conditions were equal to test conditions.
- Breeding: Parthenogenetic reproduction. 100 - 200 adults were held for breeding in 3000 mL beakers with 2000 mL reconstituted water.
- Feed during breeding: 5 times per week with a suspension of green algae supplemented by trout chow and/or powder milk and/or yeast; in such quantities that food is consumed after 24 hours
- Pre-treatment: 24 hours before the start of the test reproductive daphnia are separated from the young by sieving through a 800 MicroMeter sieve. This operation is repeated immediately before the start and the young daphnia (0 - 24 h old) are retained for the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

240 mg CaCO3/L

Test temperature:

19 - 20 °C

pH:

7.7 - 7.8

Dissolved oxygen:

- 8.7 - 8.8 mg O2/L

- 96 - 98 % air saturation level

Nominal and measured concentrations:

- Nominal concentrations: 0 (blank control), 0 (vehicle control), 10, 18, 32, 58, 100 mg/L.
- Measured concentrations day 0: NR (blank control), NR (vehicle control), 11.3, 20.4, 35.4, 65.0, 101.0 mg/L, respectively.
- Measured concentrations day 2: NR (blank control), NR (vehicle control), 11.6, 20.8, 37.1, 66.6, 104.0 mg/L, respectively.
- Results were corrected for the purity of the active ingredient
See Table 1 in 'Any other information on materials and methods incl. tables'.

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL beakers (250 mL solution) covered with watch glasses
- Aeration: None
- Feeding: None during the test
- No. of organisms per vessel: 10
- No. of vessels per concentration: 2
- No. of vessels per control: 2
- No. of vessels per vehicle control: 2

TEST MEDIUM / WATER PARAMETERS
- Reconstituted water produced by dissolving:
65 mg NaHCO3
294 mg CaCl2; 2 H2O
123 mg MgSO4; 7 H2O
6 mg KCl
in 1000 mL bidistilled water. The water was aerated with clean air for at least 24 h before use.
- Total hardness: 240 mg CaCO3/L.
- Intervals of water quality measurement: pH, O2 and temperature were measured at the beginning and at the end of the test.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours daily
- Light intensity: Fluorescent light, < 800 lux

EFFECT PARAMETERS MEASURED:
Observations of immobility were made 3, 6, 24 and 48 hours after the addition of organisms to the test vessels.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

An overview of the results is provided in Table 2 in 'Any other information on results incl. tables'.
After 48 hours exposure, no immobility of daphnia was observed in the controls or any test item treated groups.

Table 2. Immobility of Daphnia magna after 3, 6, 24 and 48 hours of exposure to the test substance and effect parameters 

Nominal concentration	Immobilised daphnids after 3 hours		Immobilised daphnids after 6 hours		Immobilised daphnids after 24 hours		Immobilised daphnids after 48 hours
(mg test item/L)	Number	%	Number	%	Number	%	Number	%
Blank Control	0	0	0	0	0	0	0	0
Vehicle Control	0	0	0	0	0	0	0	0
10	0	0	0	0	0	0	0	0
18	0	0	0	0	0	0	0	0
32	0	0	0	0	0	0	0	0
58	0	0	0	0	0	0	0	0
100	0	0	0	0	0	0	0	0
EC50 mg/L	N.D.		N.D.		>100		>100
95% Confidence limits	N.D.		N.D.		None		None

N.D..:      Not determined

 

Deviations from test guideline
The highest test concentration is 100 mg/L. The highest vehicle concentration is 553 mg/L. The stock solution was prepared with reconstituted water. Oxygen and pH were measured at the beginning and the end of the test only. Immobilized daphnids were not counted after 12h exposure.

Validity criteria
It is noted that the test guideline was EPA and the study was not GLP. In addition, it was noted that the expiry date of the test item, validity criteria and LOQ were not reported in the original study. However, this was not regarded as having a significant impact on the outcome of the study. Taking into consideration the assessment made during the first review (1997) and with the reservation that guidelines have developed since then, there is no reason not to consider the results still acceptable.

Validity criteria fulfilled:

yes

Remarks:

See validity criteria in ‘Any other information on results incl. tables’

Conclusions:

In a 48-h toxicity study on Daphnia magna, following EPA guideline EG-1, the EC50 was determined to be > 100 mg/L (the highest concentration tested), based on nominal concentrations.

Executive summary:

The toxicity of the test item on Daphnia magna was investigated in a static study following EPA guideline EG-1 (8/10/82). It is not specified whether the study meets GLP criteria or not. Daphnia magna (≤ 24 hours old) was exposed to the test substance at concentrations of 0 (blank control), 0 (vehicle control; DMSO/Arkopal N150), 10, 18, 32, 58, and 100 mg/L (measured concentrations day 0: NR, NR, 11.3, 20.4, 35.4, 65.0, 101.0 mg/L, respectively; Measured concentrations day 2: NR, NR, 11.6, 20.8, 37.1, 66.6, 104.0 mg/L, respectively) for 48 hours. Analytical results were corrected for the purity of the active ingredient. Ten Daphnia were introduced into each of 2 replicate test vessels per treatment and control. To check the concentrations of the test item, water samples were taken at 0 and 48 hours and analysed by using HPLC. The test conditions were as follows: temperature 19 - 20 °C, pH 7.7 - 7.8 and dissolved oxygen in a range of 96 - 98 % air saturation. Observations of immobility were made 3, 6, 24 and 48 hours after the addition of the organisms to the test vessels.

After 48 hours of exposure, no immobility of daphnia was observed in the controls and all treatments. Based on the findings, the EC50 of the test item was determined to be > 100 mg/L (the highest concentration tested), based on nominal concentrations.

Description of key information

Two short-term toxicity studies on aquatic invertebrates are available and included as key studies.

Freshwater, 48-h EC50 > 100 mg/L (based on nominal concentrations), static, Daphnia magna, immobility, EPA guideline EG-1, Rufli, 1984

Marine water, 96-h LC50 140 mg/L (based on mean measured concentrations), static, Mysidopsis bahia, mortality, EPA guideline 72-3, LeLievre,1990

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

> 100 mg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

LC50

Effect concentration:

140 mg/L

Additional information

Two short-term toxicity studies on aquatic invertebrates are available, one in freshwater and one in marine water. Both are selected as key studies. The freshwater study was performed according to EPA guideline EG-1. It is not specified whether or not the study was performed under GLP. Water fleas (Daphnia magna) were exposed to the test item under static condition at nominal concentrations of 10, 18, 32, 58 and 100 mg/L (measured concentrations day 0: NR, NR, 11.3, 20.4, 35.4, 65.0, 101.0 mg/L, respectively; Measured concentrations day 2: NR, NR, 11.6, 20.8, 37.1, 66.6, 104.0 mg/L, respectively) for 48 hours. One blank control group was exposed to dilution water only and one vehicle control group was exposed to the solvent (DMSO/ARKOPAL N150). Ten Daphnia were introduced into each of 2 replicate test vessels per treatment and per control. The test organisms were assessed for toxic effects at 3, 6, 24 and 48 hours. The test conditions were as follows: temperature 19 - 20 °C, pH 7.7 - 7.8 and dissolved oxygen in a range of 96 - 98 % air saturation. The 48-hour EC50 was determined to be > 100 mg/L, based on nominal concentrations.

The marine water study was conducted according to EPA OPP 72-3 and was in compliance with GLP principles. Mysid shrimp (≤ 24 hours old) were exposed to the test substance at concentrations of 0 (blank control), 24, 42, 66, 110, 180, and 300 mg/L (mean measured concentrations: <5.0/5.2, 18, 27, 46, 82, 85, and 220 mg/L, respectively) for 96 hours. Ten mysid shrimps were introduced into each of 2 replicate test vessels per treatment and control. The test conditions were as follows: temperature 25±1 °C, pH 7.6 - 8.0, dissolved oxygen in a range of 80 - 111 % air saturation, salinity 32 ‰. The examination of the number of mortalities and biological observations were made after 24, 48, 72 and 96 hours of exposure. The LC50 of the test item was determined to be 140 mg/L, based on mean measured concentrations. The NOEC was determined to be 46 mg/L.

5 other short-term toxicity studies to evaluate the effect of 5 separate degradation products on the mobility of Daphnia magna according to OECD TG202 are available. The 48 h EC50 values determined for the metabolites were all higher than the highest mean measured concentrations in the studies (from  >86 mg/L to >101 mg/L) showing that these degradation products were not significantly  more toxic as the parent compound.