Pirimiphos-methyl

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:

11 Oct 2011 to 13 Oct 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2004

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Version / remarks:

1996.

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

other: JMAFF Test Guidelines, 2-7-2-1, Daphnia immobilization

Version / remarks:

2001

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

For determination of the actual test item concentrations, duplicate samples were taken from each treatment before the start of the test and at the end of the test after 48 hours. The concentrations the test substance were determined in the duplicate test medium samples per test concentration and in one of the duplicate control samples from both sampling dates (0 and 48 hours).

Vehicle:

yes

Remarks:

N,N-Dimethylformamide

Details on test solutions:

The application solution for the dosage of the highest test concentration was prepared by dissolving 50.08 mg of the test item in 50 mL of N,N-Dimethylformamide using intense stirring. This application solution was diluted with N,N-Dimethylformamide to prepare the application solutions for the dosage of the lower test concentrations

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna Straus
- Strain/clone: Clone 5
- Age at study initiation (mean and range, SD): 6-24 hours old
- Feeding during test: No

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

150 mg/L as CaCO3

Test temperature:

21°C.

pH:

7.9 - 8.0

Dissolved oxygen:

8.4 - 8.9 mg/L

Nominal and measured concentrations:

- Nominal test concentrations: 46, 100, 220, 460 and 1000 ng/L.
- Mean measured concentreation: 44, 102, 218, 453, 952 ng/L
See Table 1 in "Any other information on materials and methods incl. tables"

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL glass beakers containing 125 mL of test medium, covered with glass plates
- Type: Closed
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4
- Aeration: No

TEST MEDIUM / WATER PARAMETERS
-Test medium:Reconstituted water according to ISO 6341. However, to meet both the US EPA OPPTS and OECD requirements, the hardness was lowered by a factor of 1.7 of the normal hardness. The test water was aerated prior to the start of the study until oxygen saturation was reached.
- Ca/mg ratio: 4:1

VEHICLE CONTROL PERFORMED: yes

OTHER TEST CONDITIONS
- Lighting: The test was performed in the dark

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

314 ng/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

218 ng/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

After 48 hours of exposure, no immobilized test organisms were determined in the control and up to and including the mean measured test item concentration of 218 ng/L. At the next two higher mean measured concentrations of 453 and 952 ng/L, all test organisms were found to be immobile. The test is considered to be valid, as in the solvent control no daphnids showed immobilization or other signs of disease or stress (e.g., discoloration or unusual behavior such as trapping at the surface water) after 48 hours test duration. Furthermore, the dissolved oxygen concentration at the end of the test was ≥3 mg/L in the control and test vessels. See Table 1 in "Any other information on results incl. tables"

Results with reference substance (positive control):

For evaluation of the quality of the daphnia clone and the experimental conditions, potassium dichromate is tested as a positive control twice a year. The result of the latest positive control test in April 2011 (48-hour EC50: 0.62 mg/L, Harlan Laboratories Study D25745) showed that the sensitivity of the test organisms was within the internal historical range (48-hour EC50 from 2000 to 2011: 0.43-1.1 mg/L).

Reported statistics and error estimates:

24 and 48 hour LC50 values and 95% confidence intervals were determined by probit analysis.

Table 1. Effect of the test substance on the mobility of Daphnia magna after 24 hours and 48 hours.

Mean measured concentration (ng/L)	Immobilised daphnids after 24 hours		Immobilised daphnids after 48 hours
	Number	%	Number	%
Control	0	0	0	0
Solvent control	0	0	0	0
44	0	0	0	0
102	0	0	0	0
218	0	0	0	0
453	2	10	20	100
952	16	80	20	100
EC50(ng/L)	692		314
95% confidence limits (ng/L)	574 - 881		218 - 453
NOEC (ng /L)	not calculated		218

Validity criteria fulfilled:

yes

Remarks:

The solvent control showed no immobilization on daphnids and the dissolved oxygen concentration at the end of the test was ≥3 mg/L in the control and test vessels

Conclusions:

The 48 hour EC50 value was determined to be 314 ng/L corresponding 95% confidence limits of 218 to 453 ng/L.

Executive summary:

The acute toxicity of the test substance to Daphnia magna was determined under static conditions. The study was conducted in accordance with OECD TG 202 and in compliance with GLP criteria. 20 daphnids (5 per vessel) were exposed to a series of nominal concentrations of 46, 100, 220, 460 and 1000 ng/L, alongside a dilution water control and a solvent control. Mean measured concentrations were determined to be 44, 102, 218, 453 and 952 ng/L, respectively. No immobilization was found at concentrations of 44, 102 and 218 ng/L test substance after 48 hours. However, 100% immobilization was determined at higher concentrations including 453 and 952 ng/L test substance. Based on these findings, the 48-h EC50 was determined to be 314 ng/L, with 95% confidence limits of 218 to 453 ng/L.

Description of key information

48-h EC50 = 314 ng/L, Daphnia magna, static regime, immobilization, OECD TG 202, Liedtke 2015

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

0.314 µg/L

Additional information

The acute toxicity of the test substance to Daphnia magna was determined under static conditions. The study was conducted in accordance with OECD TG 202 and in compliance with GLP criteria. 20 daphnids (5 per vessel) were exposed for 48 hours to a series of nominal concentrations of 46, 100, 220, 460 and 1000 ng/L, alongside a dilution water control and a solvent control. Mean measured concentrations were verified by chemical analysis using LC/MS/MS and were determined to be 44, 102, 218, 453 and 952 ng/L, respectively. The test was carried out under the following conditions: temperature 21 °C, pH 7.9 – 8.0, dissolved oxygen concentration 8.4 – 8.9 mg/L (>60% of saturation). The water parameters were measured at the start and end of the test. The mobility of the organisms was observed at 24 and 48 hours.

 

No immobilization was observed in the controls and at 44, 102 and 218 ng/L after 48 hours. However, 100% immobilization was determined at higher concentrations including 453 and 952 ng/L test substance. Based on these findings, the 48-h EC50 was determined to be 314 ng/L, with 95% confidence limits of 218 to 453 ng/L.