Pirimiphos-methyl

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 Jan 1978 to 3 Feb 1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

no guideline followed

Principles of method if other than guideline:

The acute toxicity of the test substance to rainbow trout of was determined in freshwater at 12°C at for 96 hours. LC50 values and 95% confidence intervals were derived by probit analysis.

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

Analytical samples were taken after 24, 48, 72 and 96 hour exposure. Samples and standards held at 4 °C in a refrigerator are stable for at least 24 hours.

Vehicle:

yes

Remarks:

Ethanol

Details on test solutions:

10.00 g of the test substance was weighed and dissolved in 95% purity ethanol. The ethanol concentration in each exposure vessel was adjusted to 2000 mg/L. The dilution ratio of the stock concentrates to freshwater was 1:190 in this study.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout
- Source: Samaaki Trout Farm, Wiltshire.
- Acclimation period: 1 day
- Holding condition: Temperature 8.5°C in stock ranks prior testing and in the test vessel at a temperature of 12°C-0.5°C.
- Weight of control fish: The fish ranged in weight from 5.10g - 10.59g with a mean weight of 7.49g.
- Length of control fish: The range in length was 77 to 104 mm with a mean length of 86 mm.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

Series I and II: 30-32 mg/L as CaCO3
Series III: 40-53 mg/L as CaCO3

Test temperature:

12°C - 0.5°C

pH:

7.5 to 7.65

Dissolved oxygen:

87-96%

Nominal and measured concentrations:

- Nominal concentration: 0.18, 0.32, 0.42, 0.56, 0.75, 1.0, 2.4 and 5.6 mg/L
- Mean measured concentrations: 0.18, 0.306, 0.33, 0.51, 0.56, 0.74, 2.3, NA mg/L, respectively

Details on test conditions:

TEST SYSTEM
- Test vessel: Twenty liter glass vessels
- Type: Open
- Type of flow-through: The concentrated stock solutions were fed to the system by a series of peristaltic pumps and a further series of these pumps was used to supply freshwater. The concentrated solutions of the test substance and freshwater were fed to glass splash heads where mixing occurred before the test solution p assed int-o the fish test vessels.
- No. of organisms per vessel: 20
- No. of vessels per concentration: 1
- No. of vessels per control: 1 vessel for the freshwater only control
- No. of vessels per vehicle control: 3 vessels for the solvent control
- Biomass loading rate: Not reported

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Distilled water
- Intervals of water quality measurement: Daily

OTHER TEST CONDITIONS
- Photoperiod: Not reported
- Light intensity: Not reported

EFFECT PARAMETERS MEASURED: Mortality
The mortalities of the fish in each concentration tested were recorded at 24, 48, 72 and 96 hours.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

0.404 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Basis for effect:

mortality (fish)

Details on results:

Overview of the results are provided in the 'Any other information on results incl. tables'.
There were no mortalities at the lowest concentration tested, 0.18 mg/L of the test substance as the fish did not exhibit any toxic symptoms at 96 hours, this may be regarded as a no effect level under the test conditions. After 96 hours, no mortality was observed in any of these controls. Atthe lowest test concentration of 0.18 mg/L fish did not exhibit any toxic symptoms at 96 hours.The mortality increased to 30% in 0.32 mg/L and 100% to 0.75mg/L after 96h exposure. Based on these findings, the LC50 was determined to be 0.404 mg/L with 95% confidence limits of 0.364 to 0.448 mg/L.

Reported statistics and error estimates:

24, 48, 72 and 96 hour LC 50 values and 95% confidence intervals were determined by probit analysis.

Sublethal observations / clinical signs:

Table 1. Concentrations tested and corresponding observed percentage moratilities for the rainbow trout

Nominal concentration mg/L test substance	Mortality observed %
	24 hours	48 hours	72 hours	96 hours
5.6 2.4 1.0 0.75 0.56 o.42 0.32 0.18	100 100 80 45 10 0 10 0	100 100 95 85 50 15 20 0	100 100 100 100 85 30 30 0	100 100 100 100 90 40 30 0
*Control SeriesI *Control SeriesII *Control SeriesIII	0   0   0	0   0   0	0   0   0	0 0 0
Freshwateronly Control series III	0	0	0

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 value as determined to be 0.404 mg/L test substance corresponding 95% confidence limits of 0.364 to 0.448 mg/L.

Executive summary:

The acute toxicity of the test substance to rainbow trout (Oncorhynchus mykiss) was studied in a 96-hour flow-through test in freshwater at 12°C.The study did not follow established guidelines and was not in compliance with GLP. Still, the study followed the correct study principles and thetest procedures and results are well documented. The study can therefore be considered reliable (with restrictions) and fully valid for the hazard and risk characterisation.In this study, the fish (twenty organisms per concentration) were exposed to nominal concentrations of 5.6, 2.4, 1.0, 0.75, 0.56, 0.42, 0.32 and 0.18 mg/L (mean measured concentrations were determined to be NA,2.3, 0.74, 0.56, 0.51, 0.33, 0.306 and 0.18 mg/L, respectively). The mortalities of the fish in each concentration tested were recorded at 24, 48, 72 and 96 hours. A blank control and a solvent control (containing 2000 ppm of ethanol) were also tested with each series.

After 96 hours, no mortality was observed in any of these controls. Atthe lowest test concentration of 0.18 mg/L fish did not exhibit any toxic symptoms at 96 hours.The mortality increased to 30% in 0.32 mg/L and 100% to 0.75mg/L after 96h exposure. Based on these findings, the LC50 was determined to be 0.404 mg/L with 95% confidence limits of 0.364 to 0.448 mg/L.

Description of key information

All available data was assessed and the study representing the worst-case effects are included here as key. The results can be considered worst-case and are selected for the CSA.

96-h LC50 = 0.404 mg/L, Oncorhynchus mykiss, flow-through regime, no guideline followed, Hill 1978

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

0.404 mg/L

Additional information

The acute toxicity of the test substance to rainbow trout (Oncorhynchus mykiss) was studied in a 96-hour flow-through test in freshwater at 12°C. The study did not follow established guidelines and was not in compliance with GLP. Still, the study followed the correct study principles and the test procedures and results are well documented. The study can therefore be considered reliable (with restrictions) and fully valid for the hazard and risk characterisation. In this study, the fish (twenty organisms per concentration) were exposed to nominal concentrations of 5.6, 2.4, 1.0, 0.75, 0.56, 0.42, 0.32 and 0.18 mg/L (mean measured concentrations were determined to be NA, 2.3, 0.74, 0.56, 0.51, 0.33, 0.306 and 0.18 mg/L, respectively). The mortalities of the fish in each concentration tested were recorded at 24, 48, 72 and 96 hours. A blank control and a solvent control (containing 2000 ppm of ethanol) were also tested with each series.

After 96 hours, no mortality was observed in any of these controls. At the lowest test concentration of 0.18 mg/L fish did not exhibit any toxic symptoms at 96 hours. The mortality increased to 30% in 0.32 mg/L and 100% to 0.75 mg/L after 96h exposure. Based on these findings, the LC50 was determined to be 0.404 mg/L with 95% confidence limits of 0.364 to 0.448 mg/L.