Pirimiphos-methyl

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

adult fish: sub(lethal) effects

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 May 1990 to 26 Jun 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 204 (Fish, Prolonged Toxicity Test: 14-day Study)

Version / remarks:

The study is extended to 28 days including growth measurement

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples of the test solutions were taken for analysis on days 1, 2, 3, 6, 7, 9, 13, 15, 21 and 23. The samples were taken from the middle of each test vessel.

Vehicle:

yes

Remarks:

Triethylene glycol

Details on test solutions:

Stock solutions (each nominally 10,000 x the strength of the respective test solution) were prepared by weighing into glass jars the amount of test substance required and making up to a nominal 300 mL with triethylene glycol. The stock solutions were then stirred to ensure complete mixing. The stock solution for the solvent control consisted of 300 mL of triethylene glycol alone. Stock solutions were replaced on days 7, 14 and 21. All test concentrations and the solvent control contained 0.1 mL of triethylene glycol per L.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow Trout
- Length at study initiation: Mean length of 54 mm (range: 47-61 mm)
- Weight at study initiation: Mean weight of 2.52 g (range: 1.56-3.30 g)

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

28 d

Hardness:

55.6- 69.6 mg/L as CaCO3

Test temperature:

13.8- 15.2 °C

pH:

7.4- 8.0

Dissolved oxygen:

9.2- 10.6 mg/L

Conductivity:

172- 206 µS/cm

Nominal and measured concentrations:

- Nominal concentrations: 0.025, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/L test substance
- Mean measured concentrations: 0.023, 0.046, 0.10, 0.20, 0.40, 0.70 mg/L test substance
See Table 1 in 'Any other information on materials and methods incl. tables'.

Details on test conditions:

TEST SYSTEM
- Test vessel: 45 liter
- Type: Open
- Type of flow-through: The apparatus used in this study was a dynamic, continuous flow-through system. The test vessels, dosing lines, mixing chambers and stock vessels were all constructed of glass. A minimum quantity of silicone rubber tubing was used to connect the components together. Glass vessels with a maximum capacity of 54 litres and a working volume of 45 litres were used to hold the test fish. The test solutions were renewed at a nominal rate of 250 ml/minute so that a 95% exchange of the test solutions was calculated to occur within 9 hours. The stock solutions were fed to the glass mixing chambers by a series of Watson-Marlow peristaltic pumps and the dilution water was supplied using a capillary flow control system. Magnetic stirrers in the mixing chambers were used to ensure mixing before the test solutions passed into the fish exposure vessels. The dilution ratio of the stock solutions to dilution water was nominally 1:10,000 in all concentrations. Calibration of the dilution water and toxicant flow rates was undertaken daily for the first three days and then 3 times per week. The dilution water flow rates were measured by collecting for 1 minute prior to input to the test vessels. The stock solution flow rates were calculated after weighing the stock solutions over a known period of time.
- Renewal rate of test solution (frequency/flow rate): 250 mL/minute
- No. of organisms per vessel: 10
- No. of vessels per concentration: 1
- No. of vessels per control: 1
- No. of vessels per vehicle control: 1
- Biomass loading rate: 1.78 g/L

TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water: The dilution water was dechlorinated tap water. The water was supplied via a 100m3 reservoir with an average retention time of 24 hours. It was passed through activated carbon, filtered to remove particulate material and dechlorinated with sodium thiosulphate. The treated water was then held in a secondary reservoir with a capacity of 36 m3 and an average retention time of 8 hours. It was delivered to the test system via a temperature controlled header tank at a nominal temperature of 15°C.
- Alkalinity: 33.1 – 38.5 mg/L as CaCO3
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16:8
- Light intensity: Not reported

WATER QUALITY MEASUREMENTS
The dissolved oxygen, pH and temperature were measured in each test vessel daily for the first 3 days and then 3 times per week until the end of the study. In addition, the water hardness, conductivity and the free and residual chlorine content of the dilution water were determined daily. Measurements of pH were carried out with a pH meter. Dissolved oxygen values were measured with a dissolved oxygen meter. Temperature values were determined for all vessels by a mercury-in-glass thermometer calibrated to 0.1°C. A continuous record of the temperature in one vessel was also made using a thermistor probe linked to a chart recorder. Conductivity was measured with a conductivity meter. Hardness was determined by titration with standard EDTA solution using BDH total hardness indicator and alkalinity was measured by an electrometric method.

EFFECT PARAMETERS MEASURED
Observations of mortalities and symptoms of toxicity were made daily. Mortalities were recorded daily and symptoms of toxicity were recorded on days 4, 7, 10, 14, 21 and 28.

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

< 0.023 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Basis for effect:

weight

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

0.023 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Basis for effect:

weight

Details on results:

Overview of the results were provided in table 1 and table 2 in 'Any other information on results incl. tables'.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

4, 7, 10, 14, 21 and 28 day LC50 values and 95% confidence intervals were determined.

Tabel 1. Summary of mean fish weights (determined by bulk weighing) and conseqent feeding rates

Nominal concentration oftest substance technical mg/L	Mean measured concentration of test substance technical mg/L	Day 0 (29.5.90)		Day 14 (12.6.90)			Day 28 (26.6.90)
		Mean fishweight in g	Nominal foodweight/day in g	Mean fishweight in g	Nominal foodweight/day in g	% change in fishweight from day 0	Mean fishweight in g	% change in fishweight from day 0
0.80	0.79	1.51	0.30	1.99*	0.12	+32	1.11*	-26
0.40	0.40	1.78	0.36	1.57	0.25	-12	1.50	-16
0.20	0.20	1.57	0.31	1.42	0.28	-10	1.21	-23
0.10	0.10	1.49	0.30	1.43	0.26	-4	1.26	-15
0.05	0.046	1.79	0.36	1.75	0.35	-2	1.62	-10
0.025	0.023	1.77	0.35	1.90	0.38	+7	2.00	+13
Solvent control	-	1.62	0.32	2.12	0.42	+31	2.75	+70
Dilutionwater control	-	1.78	0.36	2.22	0.44	+25	2.72	+53

Table 2. Summary of percentage mortalities during test

Nominal concentration test substance technical mg/L	Mean measured concentration test substance technical mg/L	Cumulative percentage mortality observed
		4 days (2.6.90)	7days (5.6.90)	10days (8.6.90)	14 days (12.6.90)	21 days (19.6.90)	28 days (26.6.90)
0.80	0.79	70	70	70	70	70	70
0.40	0.40	10	20	20	20	20	20
0.20	0.20	0	0	0	0	0	10
0.10	0.10	0	0	0	10	10	10
0.05	0.046	0	0	0	0	0	0
0,025	0.023	0	0	0	0	0	0
Solvent control	-	0	0	0	0	0	0
Dilution water control	-	0	0	0	0	0	0

Validity criteria fulfilled:

not specified

Conclusions:

Based on the effects on growth observed at all concentrations, the LOEC was determined at 0.023 mg/L and the NOEC was determined at <0.023 mg/L (mean measured concentration) in fish after 28 days exposure.

Executive summary:

The chronic effect of continuous exposure to the test substance on fish was evaluated in a flow-through prolonged toxicity test with the freshwater rainbow trout (Oncorhynchus mykiss). The test was performed similar to OECD TG 204 (extended to 28 days) and in compliance with GLP. The effect assessment of this 28 days exposure test was based on mortality and symptoms of toxicity. The fish (one vessel per concentration, containing 10 fish each) were exposed to nominal concentrations of 0.025, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/L of the test substance. The mean measured concentrations, determined by gas chromatography, were determined to be 0.023, 0.046, 0.10, 0.20, 0.40 and 0.79 mg/L, respectively. Mortalities were recorded daily and symptoms of toxicity were recorded on days 4, 7, 10, 14, 21 and 28.

 

At mean measured concentrations of 0.10, 0.20, 0.40, 0.79 mg/L, mortalities at the end of the exposure were 10%, 10%, 20% and 70%, respectively. No mortalities were shown after 28 days exposure at a mean measured concentration of 0.023 and 0.046 mg/L of the test substance. The threshold levels of lethal effects was determined at 0.10 mg/L. The increase in weight by day 28, of the dilution water and solvent control fish was 53 and 70% respectively. The change in weight of surviving fish for all test concentrations by day 28 ranged from -26 to + 13%. It is therefore concluded that fish weight gain was reduced at all test concentrations in comparison with the controls. Based on these findings, the NOEC of the test was determined to be <0.023 mg/L on the basis of mean measured concentrations.

Description of key information

Freshwater, 28-d NOEC ≤ 0.023 mg/L, Oncorhychus mykiss, OECD TG 204 (extended), Sankey 1990

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

NOEC

Effect concentration:

<= 0.023 mg/L

Additional information

The chronic effect of continuous exposure to the test substance on fish was evaluated in a flow-through prolonged toxicity test with the freshwater rainbow trout (Oncorhynchus mykiss). The test was performed similar to OECD TG 204 (extended to 28 days) and in compliance with GLP. The effect assessment of this 28 days exposure test was based on mortality and symptoms of toxicity. The fish (one vessel per concentration, containing 10 fish each) were exposed to nominal concentrations of 0.025, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/L of the test substance. The mean measured concentrations, determined by gas chromatography, were determined to be 0.023, 0.046, 0.10, 0.20, 0.40 and 0.79 mg/L, respectively. Mortalities were recorded daily and symptoms of toxicity were recorded on days 4, 7, 10, 14, 21 and 28.
At mean measured concentrations of 0.10, 0.20, 0.40, 0.79 mg/L, mortalities at the end of the exposure were 10%, 10%, 20% and 70%, respectively. No mortalities were shown after 28 days exposure at a mean measured concentration of 0.023 and 0.046 mg/L of the test substance. The threshold levels of lethal effects were determined at 0.10 mg/L. The increase in weight by day 28, of the dilution water and solvent control fish was 53 and 70% respectively. The change in weight of surviving fish for all test concentrations by day 28 ranged from -26 to + 13%. It is therefore concluded that fish weight gain was reduced at all test concentrations in comparison with the controls. Based on these findings, the NOEC of the test was determined to be <0.023 mg/L on the basis of mean measured concentrations.