pymetrozine (ISO); (E)-4,5-dihydro-6-methyl-4-(3-pyridylmethyleneamino)-1,2,4-triazin-3(2H)-one

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05 Aug 1994 to 07 Aug 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)

Version / remarks:

1993

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Analytical determination of test material concentration (active ingredient) was performed with samples collected from each replicate test vessel after 0 and 48 hours. The primary stock solution was sampled at the beginning and end of the test. The samples were stored in 40 mL amber glass vials and samples or extracts were refrigerated if not analyzed on the day of collection. Samples collected from replicate 1 test vessels at initiation and replicate 2 test vessels at termination were extracted and analyzed, and the other replicate sample was stored as back-up.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution with a nominal concentration of 130 mg/L was prepared by combining 250 g of test substance with dilution water in a 500 gallon polyethylene tank and adjusting the final volume to 500 gallons with dilution water. The stock solution was mixed overnight until all test substance was dissolved. Appropriate amounts of the stock solution were added directly to dilution water by a proportional diluter.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: daphnid
- Age: < 24 hours
- Source: Laboratory cultures
- Feeding: None during test

ACCLIMATION
- Acclimation period: Unknown, adult daphnids acclimated to test medium for 8 days prior to testing, under static renewal conditions
- Acclimation conditions: same as the test conditions
- Type and amount of food: freshwater algae Selenastrum capricornutum and a yeast/trout chow slurry
- Feeding frequency: daily
- Health during acclimation (any mortality observed): free of apparent sickness, injuries, and abnormalities at the beginning of the test

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

164 mg/L CaCO3

Test temperature:

19.1 - 20.2 °C

pH:

8.5 - 8.6

Dissolved oxygen:

8.5 - 8.6 mg/L (no aeration)

Conductivity:

580 - 680 µmhos/cm

Nominal and measured concentrations:

- Nominal concentration: 0.0 (control), 20, 33, 52, 78 and 130 mg/L
- Mean measured concentrations: ND (control), 19.2, 30.3, 50.4, 77.1 and 123 mg/L (see 'Any other information on materials and methods incl. tables')

Details on test conditions:

TEST SYSTEM
- Test vessel: The test was performed in 20 liter glass aquaria that contained 15 liters of test solution (water depth was approximately 18 cm). Test organisms were exposed in chambers that consisted of a glass cylinder with Nitexc mesh silicone cemented to the bottom. These cages were suspended within each test vessel.
- Aeration: Not required
- Type of flow-through (e.g. peristaltic or proportional diluter): The test substance was supplied to the test vessels under flow through conditions by an intermittent flow proportional diluter. The diluter allowed test substance to contact only glass, stainless steel, or Teflon-coated surfaces. The diluter was calibrated before and after the test. During the test the diluter was activated 310 times, resulting in an average of 5.2 volume additions per 24 hours in each test vessel.
- No. of organisms per vessel: 10
- No. of vessels per concentration: 2
- No. of vessels per control: 2
- Loading rate: a loading rate during the toxicity test of approximately 0.11 mg/Lat any time and 0.02 mg/L/24 hours.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Carbon filtered, dechlorinated tap water adjusted to a hardness of 160 to 180 mg CaCO3/L
- Alkalinity: 106 mg/L (as CaCO3)

WATER QUALITY PARAMETERS
Dissolved oxygen (YSI Model 57 meter; instrument number 1), pH (Beckman model pBI 12 meter; instrument number 96), conductivity (Cole Parmer meter; instrument number 94), and temperature (Beckman model pHI 12 meter; instrument number 96, probe pHT-1) were measured and recorded daily in each test chamber that contained live animals. The temperature in one test vessel was recorded continuously during the test.
OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: A 16 hour light and 8 hour dark photoperiod with a 15 minute transition period was automatically maintained.
- Light intensity: cool-white fluorescent lights that provided a light intensity of 41 footcandles.

EFFECT PARAMETERS MEASURED : immobilization and sub-lethal effects
- The number of surviving organisms and the occurrence of sublethal effects (lethargy and immobilization) were determined visually and recorded after 24 and 48 hours.

RANGE-FINDING STUDY
An initial screening test with the test substance was conducted under static conditions. Nominal concentrations of the test substance were 0.1, 1, 10, 65, and 130 mg/L. After 48 hours there was greater than 50% survival at 0,1, 1, 10, and 65 mg/L, and 40% survival at 130 mg/L.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

87 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other:

Remarks:

95% confidence limit: 68.0 to 130 mg/L

Details on results:

The results are tabulated in 'Any other information on results incl. tables'.
- Solubility of the test substance: Insoluble material was not observed in any test vessel during the test.
- Mortality of control: 100% survival occurred in the control and no-control sublethal effects were noted during the exposure period.
- Abnormal responses: Daphnids exposed to 50.4, 77.1, and 123 mg/L were less active than controls after 24 hours of exposure. After 48 hours surviving daphnids exposed to 19.2 and 30.3 mg/L were less active than controls, while daphnids exposed to 50.4, 77.1, and 123 mg/L were immobilized.

Reported statistics and error estimates:

Results of the toxicity test were interpreted by standard statistical techniques (Stephan, 1983). The 24 and 48 hour LC50 values were calculate by the author using the number of dead organisms and the mean measured concentrations of test substance, The no observed effect concentration is the concentration of test substance that allowed at least 90% survival and did not cause any sublethal effects. The no mortality concentration is the highest concentration of test substance that allowed at least 90% survival.

Tabel 1: survival and sublethal effect data from the toxicity test with the test substance and the daphnid, Daphnia magna

Mean Measured concentration(mg/L)		Number alive				Number affected
		0 h	24 h	48 h	0 h		24 h	48 h
0.0 (control)	1	10	10	10	0		0	0
	2	10	10	10	0		0	0
19.2	1	10	10	9	0		0	9
	2	10	10	10	0		0	10
30.3	1	10	10	9	0		0	9
	2	10	9	9	0		0	9
50.4	1	10	10	7	0		10	7
	2	10	10	9	0		10	9
77.1	1	10	10	6	0		10	6
	2	10	10	4	0		10	4
123	1	10	10	2	0		10	2
	2	10	10	5	0		10	5

 

Validity criteria fulfilled:

yes

Remarks:

see 'Any other information on materials and methods incl. tables'

Conclusions:

In an acute toxicity test with Daphnia magna, the 48-hour LC50 for the test substance was 87.0 mg/L with 95 % confidence interval of 67.9 – 131.0 mg/L.

Executive summary:

The acute toxicity of the test substance was tested to the daphnid, Daphnia magna, magna in accordance with US EPA FIFRA Guideline 72-2 and in compliance with GLP-criteria. The test was performed under flow-through conditions, for 48 hours, with five concentrations of test substance and a dilution water control at a temperature of 20 ± 1°C. The dilution water was filtered dechlorinated tap water adjusted to a hardness of 160 to 180 mg/L. Nominal concentrations of the test substance were: 0.0 mg/L (control), 20, 33, 52, 78, and 130 mg/L. Mean measured concentrations of the test substance in test media were: ND (not detected at or above the analytical detection limit of 4.00 mg/L, control), 19.2, 30.3, 50.4, 77.1, and 123 mg/L and concentrations were stable during the 48 hour testing period. Mean measured concentrations were used for all calculations. Organisms used in the test were produced from in house cultures maintained and acclimated under test conditions. After 48 hours of exposure the control organisms had an average wet weight (blotted dry) of 0.17 mg. All animals were in good condition at the beginning of the study. Exposure of daphnids to the test substance resulted ina 48 hour median lethal concentration (LC50) of 87.0 mg/L, with a 95% confidence interval of 67.9 to 131 mg/L. The 48 hour no observed effect concentration was less than 19.2 mg/L, the lowest tested concentration.

Description of key information

All available data was assessed and the studies representing the worst-case effects were included as weight-of-evidence studies. Other studies are included as supporting information. The weight-of-evidence studies are considered to be worst-case and were selected for the CSA.

 

- 48-h LC50 = 87.0 mg/L in freshwater invertebrates (Daphnia magna), EPA OPP 72-2, Boeri, 1994

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

87 mg/L

Additional information

Table: Overview of available data on short-term toxicity to aquatic invertebrates

Species	Guideline / GLP	Endpoint	Effect value	Comment	Reference
Daphnia magna	EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)	48-h LC50	87.0 mg/L	Based on mean measured concentrations and growth rates.	Boeri, 1994