Mecoprop

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:

19 August 2003 to 11 September 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Japanese MAFF guideline 12-Nousan-N° 8147 § 2-7-2-1

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 200, 100, 50, 25, 13, 6.5, 0 (Control) mg/L
- Sampling method: At the beginning and at the end of the test, aliquots of 10 mL of the test solutions were taken from the test flasks to determining the test material concentration. Analysis of the test material concentration was carried out using HPLC and UV absorption detector.
- Sample storage conditions before analysis: Refrigerator (approximately 5 °C).

Vehicle:

yes

Remarks:

Water

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Range Finding Test: The primary stock solution (100 mg/L) was prepared dissolving 100 mg of the test material in 1 000 mL of dilution water M4. To assist the solubilisation of the test material it was applied ultrasonic dispersion for 10 minutes and magnetic stirring for 20 minutes. The test concentration obtained were: 100, 10, 1, 0.1, 0.01 mg/L. Secondary stock solutions were prepared from dilutions of the primary stock solution.
- Definitive Test: Based on the results obtained in the range-finding test, a primary stock solution was prepared with nominal concentration of 200 mg/L. To prepare this solution, 50 mg of test material was firstly dissolved into 40 mL of dilution water M4, and the volume was completed to 250 mL. To assist the solubilisation of the test material it was applied ultrasonic dispersion for 10 minutes, and magnetic stirring for 20 minutes. Test concentrations obtained were 200, 100, 50, 25,13, 6.5 mg/L

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Age at study initiation: 24 hours
- Culture containers: The stock culture was maintained in approximately 2.5 L glass containers filled with approximately 2.0 L of M4 medium.
- Handling of culture: In each culture container 30 organisms were maintained daily. They were daily fed with algae suspension (Pseudokirchneriela subcapitata) with 10^7 cells/ organism. The water of each culture renewed twice a week.
- Feeding during test: During the 48 hours test period, the test system was not fed.
- Method of breeding: Nearly 24 hours before the Acute Toxicity Test started, Daphnia with eggs were isolated in crystallisers and fed with algae suspension. In the following morning, the newly born Daphnia, aged 24 hours, were separated from the adults and used in the test.

Test type:

static

Water media type:

other: Reconstituted water (M4 medium)

Limit test:

yes

Total exposure duration:

48 h

Hardness:

249.3 to 251.3 mg/L CaCO3

Test temperature:

20.4 to 20.9 °C

pH:

5.5 - 7.6

Dissolved oxygen:

7.7 - 8.1 mg/L

Conductivity:

650 μS/cm

Nominal and measured concentrations:

Nominal concentrations: 6.5; 13; 25; 50; 100 and 200 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 30 mL glass beakers. All glassware used in the test was washed with neutral detergent, commercial acetone, nitric acid 5 %, and rinsed with tap water followed by deionised water.
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4
- The organisms were distributed randomly in the test container. Firstly, three organisms were placed in each test container and, finally, two organisms were added to the container.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water (M4 Medium) was prepared using distilled and deionised water and adding appropriate amounts of salts, with total hardness of 250 ± 25 mg/L CaCO3 and pH ranging from 7 to 8.

OTHER TEST CONDITIONS
- Photoperiod and light intensity: 16 hours with luminosity of 1 000 ± 20 % lux and 8 hours in dark conditions.

VEHICLE CONTROL PERFORMED: Yes

EFFECT PARAMETERS MEASURED
- Immobility after 24 and 48 hours.
- Dissolved oxygen and pH of test solutions.
- The test substance concentrations were chemically analysed (active ingredient concentration).

RANGE-FINDING STUDY
The range-finding test was carried out in order to determine the concentrations of the test substance that caused 100 % and 0 % of acute toxic effect to the test organisms.
The exposure conditions were:
- Total number of organisms per each tested concentration or control: 10
- Number of replicates per each tested concentration and control: 2
- Number of organisms per test container: 5
- The organisms were distributed randomly in the test container. First, three organisms were placed in each test container and, finally, two organisms were added to the container.
- Temperature of test solutions: 20.4 to 20.7 °C.
- Photoperiod: 16 hours with luminosity of 1 000 ± 20 % lux and 8 hours in dark conditions.
- Parameters evaluated: Immobility after 24 and 48 hours.
- Test concentrations: 0.01, 0.1, 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: In 48 hours of exposition, the concentrations that caused 100 % immobilisation to the organisms was not determined using those test material concentrations, and the concentration that caused 0 % immobilisation to the organism was 10 mg/L.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7): 0.32, 0.56, 1.0, 1.8, 2.4 mg/L and control.

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

103.53 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The 24 and 48-hour EC50 values of the test material were 118.92 mg/L (95 % confidence limits = 103.98 to 136.00 mg/L) and 103.53 mg/L (95 % confidence limits = 88.73 to 120.79 mg/L), respectively.
The highest concentration tested that did not cause acute effect (immobility) to the organisms after 48 hours was 50 mg/L. The lowest concentration that caused 100 % immobility was 200 mg/L.

Results with reference substance (positive control):

The 24-hour EC50 value of the reference substance (potassium dichromate) was 1.06 mg/L (95 % confidence limits = 0.93 to 1.21 mg/L), showing the viability of test system.

Reported statistics and error estimates:

The 24 and 48-hour EC50 and the respective 95 % confidence limits were determined by using the statistical Trimmed Spearman-Karber Method.

Number of Immobile Organisms at 24 and 48 Hours of Exposure During the Range-Finding Test.

 

Test Concentration (Nominal) (mg/L)	Number of Immobile Organisms				% of Total Immobility in 48 Hours
	24 Hours		48 Hours
	A	B	A	B
100	1	0	3	2	50
10	0	0	0	0	0
1	0	0	0	0	0
0.1	0	0	0	0	0
0.01	0	0	0	0	0
Control	0	0	0	0	0

A and B = Replicates with 5 organisms each.

 

Number of Immobile Organisms at 24 and 48 hours of Exposure During the Definitive Test.

 

Test Concentration (Nominal) (mg/L)	Number of Immobile Organisms								% of Total Immobility in 48 Hours
	24 Hours				48 Hours
	A	B	C	D	A	B	C	D
200	5	5	5	5	5	5	5	5	100
100	1	2	1	1	2	2	3	2	45
50	0	0	0	0	0	0	0	0	0
25	0	0	0	0	0	0	0	0	0
13	0	0	0	0	0	0	0	0	0
6.5	0	0	0	0	0	0	0	0	0
Control	0	0	0	0	0	0	0	0	0

A, B, C and D = Replicates with 5 organisms each.

Nominal and Effective Concentrations of Test Material, Mean Effective Concentration and Their Respective Deviations

Nominal Concentration (mg/L)	Effective Concentration (mg/L)		Mean Effective Concentration – EC* (mg/L)	Deviation** (%)
	0 h	48 h
200	199	195	197.0	1.5
100	98.0	98.0	98.0	2
50	50.9	49.7	50.3	0.6
25	24.9	24.4	24.65	1.4
13	12.7	12.3	12.5	3.85
6.5	6.8	6.0	6.4	1.54
Control	ND***	ND	ND	-

* Effective concentration was determined according equations above.

** Deviation (%) = [(Effective concentration- Nominal concentration) x 100]/Nominal concentration

*** ND: not determined

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the study, the 48 h EC50 in Daphnia was 103.53 mg/L.

Executive summary:

The acute toxicity of the test material to Daphnia magna was assessed according to OECD Test Guideline 202 and EU Method C.2. and in compliance with GLP in a 48 h static test.

This study was carried out in order to evaluate the acute toxicity of the test material to Daphnia magna. A range-finding test was carried out in order to determine the concentrations that caused 100 % and 0 % of acute effect. Based on these results, a definitive test was carried out using the following nominal concentrations: Control; 6.5; 13; 25; 50; 100 and 200 mg/L. Twenty organisms were used per concentration distributed into four replicates. The definitive test was conducted in a controlled environment with temperature ranging from 20.4 to 20.9 °C for 48 hours, with periods of 16 hours with luminosity of about 1 000 lux and 8 hours in the dark. The 24 and 48-hour EC50 values of the test material were 118.92 mg/L and 103.53 mg/L, respectively. The highest concentration that did not cause acute effect (immobility) to the organisms in 48 hours was 50 mg/L, and the lowest one that caused 100 % of immobilisation was 200 mg/L.

Under the conditions of the study, the 48 h EC50 in Daphnia was 103.53 mg/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Daphnia were exposed to the test material for 48 h and mortality recorded.

GLP compliance:

no

Remarks:

Study pre-dates GLP.

Analytical monitoring:

yes

Details on sampling:

2 mL of sample were mixed with 2 mL of 2' N sulphuric acid and the mixture was extracted with 4 mL of methylene chloride. The methylene chloride layer was dried with anhydrous sodium sulphate and 2 mL of it evaporated to dryness. The residue was dissolved in 1 mL of ether-methanol mixture (9:1 v/v) and treated with diazomethane. The resulting yellow-coloured solution was subjected to gas chromatography.
Gas chromatography
A Varian Aerograph (series 1200) gas chromatograph equipped with an FID-detector was used. The column had a length of 170 cm, an internal diameter of 2.5 mm and was packed with 3 % OV 1 on Chromosorb W-HP 100-120 mesh. The carrier gas flow rate (N2 ) was 15 mL/min. The injector temperature was 2S0 °C, the column temperature 150 °C and the detector temperature 250 °C. The observed retention times and peak heights were compared with those of standard solutions of the auxin herbicides and from this the auxin herbicides in the water phase of the perfusion system were identified and quantified. The retention time of the test material was 3.9 minutes.

Vehicle:

no

Details on test solutions:

The test compound was dissolved in Daphnia-medium.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Age at study initiation (mean and range, SD): 16 to 24 hours old.
- Age of parental stock: Born of three weeks old mothers.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Nominal and measured concentrations:

Several concentrations were prepared, increasing geometrically: 0, 10, 32, 100, 180, 320, 560, 1 000 mg/L.

Details on test conditions:

TEST SYSTEM
- Test vessel: Beakers
- Material, size, headspace, fill volume: 200 mL
- No. of vessels per concentration: Duplicate
- To each concentration 20 daphniae were exposed.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

420 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 400 - 450 mg/L

Reported statistics and error estimates:

LC50 at 48 hours was calculated according to Litchfield and Wilcoxon 1949.

Mortality

Test Material Concentration (mg/L)	Daphnids Living After 48 h
0	20
10	20
32	20
100	20
180	20
320	13 – 19*
560	5 – 6*
1 000	0 - 0

* Replicates

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the study the 48 h LC50 for daphnia magna was 420 mg/L.

Executive summary:

The toxicity of the test material to daphnia magna was assessed over 48 h.

Under the conditions of the study the 48 h LC50 for daphnia magna was 420 mg/L.

Description of key information

Key Study: Sesso, 2004

Under the conditions of the study, the 48 h EC50 in Daphnia was 103.53 mg/L.

Supporting Study: ten Berge (1978)

Under the conditions of the study the 48 h LC50 for daphnia magna was 420 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

103.53 mg/L

Additional information

Key Study: Sesso, 2004

The acute toxicity of the test material to Daphnia magna was assessed according to OECD Test Guideline 202 and EU Method C.2. and in compliance with GLP in a 48 h static test. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

This study was carried out in order to evaluate the acute toxicity of the test material to Daphnia magna. A range-finding test was carried out in order to determine the concentrations that caused 100 % and 0 % of acute effect. Based on these results, a definitive test was carried out using the following nominal concentrations: Control; 6.5; 13; 25; 50; 100 and 200 mg/L. Twenty organisms were used per concentration distributed into four replicates. The definitive test was conducted in a controlled environment with temperature ranging from 20.4 to 20.9 °C for 48 hours, with periods of 16 hours with luminosity of about 1 000 lux and 8 hours in the dark. The 24 and 48-hour EC50 values of the test material were 118.92 mg/L and 103.53 mg/L, respectively. The highest concentration that did not cause acute effect (immobility) to the organisms in 48 hours was 50 mg/L, and the lowest one that caused 100 % of immobilisation was 200 mg/L.

Under the conditions of the study, the 48 h EC50 in Daphnia was 103.53 mg/L.

 

Supporting Study: ten Berge (1978)

The toxicity of the test material to daphnia magna was assessed over 48 h. The study was awarded a reliability score of 2 in accordance with the criteria set forth by Klimisch et al. (1997).

Under the conditions of the study the 48 h LC50 for daphnia magna was 420 mg/L.