mecoprop-P (ISO); (R)-2-(4-chloro-2-methylphenoxy)propionic acid

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

11 November 1992 to 04 December 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: OECD-guideline for testing of chemicals No. 202: "Daphnia sp., Acute Immobilisation Test and Reproduction Test"

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EEC Guideline XI/681/86 (draft 4) "Prolonged toxicity study with Daphnia magna: Effects on reproduction"

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: At the beginning and at the end of several of the 2 - 3 day periods of the renewal scheme test samples were taken for concentration control analysis.
- Sample storage conditions before analysis: Refrigerator

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The stock solutions and different concentrations were freshly prepared before each renewal. The stock solution was prepared by weighing 271.25 mg of the test material (taking the purity of 92.2 % into account) into 500 mL medium.
- Other relevant information: The test material is a free acid which is hardly soluble in acid water. In the presence of positive ions (e.g. Na or K) in water the corresponding salt is formed, which is easily soluble.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna STRAUS
- Age at study initiation: 2 - 24 hours
- Age of stock animals: 2 - 3 weeks
- Feeding during test : Yes. Daphnia were fed on Day 0, 1, 2, 3, 5, 6, 8, 9, 10, 12, 13, 14, 15, 16, 19, 20, 21 and 22.
- Food type: During the test the daphnids were fed with increasing amounts of the algae Pseudokirchneriella subcapitata and Scenedesmus subspicatus. The algae are cultured in standard OECD 201 nutrient solution by centrifugation and stored for a maximum of 8 days until use in the dark at about 6 ± 2 ºC.
- Frequency: Daily

ACCLIMATION
- Acclimation period: The animals are kept individually in the breeding culture under standard laboratory conditions and in the same water which is used for testing.
- Acclimation conditions: 20 ± 2 ºC, low intensity artificial light, 16:8 light: dark rythm.
- Type and amount of food: A mixture of Pseudokirchneriella subcapitataSAG B 61.81and Scenedesmus subspicatus SAG 86.81.
- Feeding frequency: They are fed at least 3 times per week.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

2.70 ± 0.50 mmol/L

Test temperature:

21 ± 1 ºC

pH:

8.00 ± 0.5

Dissolved oxygen:

8.8 - 9.1 mg O2/L

Conductivity:

600 - 700 μS/cm

Nominal and measured concentrations:

Nominal concentration: 0, 1, 2.5, 10, 25, 50, 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Beakers
- Material, size, headspace, fill volume: Glasee beaker (100 mL)
- Test volume: 50 mL
- Aeration: The medium was aerated until saturated with oxygen.
- Renewal rate of test solution: Water exchanges occurred on Day 2, 5, 8, 12, 14, 16, 19 and 21.
- No. of organisms per vessel: 1
- No. of vessels per concentration: 10
- No. of vessels per control: 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The synthetic medium (reconstituated water, M7 Elendt) is used both for the culture and within according to the test. The medium is prepared on the basis of an ultrapure deionised water. The medium was aerated until saturated with oxygen. It was prepared at least 24 hours before use to allow stabilisation of the solution.
- Alkalinity up to ph 4.3: 0.90 ± 0.10 mmol/L
- Molar Ca:Mg ratio: about 4:1
- Molar Na:K ratio: about 10:1
- Conductivity: 600 - 700 μS/cm
- Macro Nutrients: 221.850 mg/L CaCl2; 60.223 mg/L MgSO4; 5.8 mg/L KCl; 64.8 mg/L NaHCO3; 4.3 mg/L Na2SiO3; 0.274 mg/L NaNO3; 0.143 mg/L KH2PO4; 0.184 mg/L K2HPO4.
- Vitamins: 75.0 µg/L Thiamine; 1.0 µg/L B12; 0.75 µg/L Biotin.
- Trace Nutrients: 0.71488 mg/L H3BO3; 0.05735 mg/L MnCl2; 0.0765 mg/L LiCl; 0.01775 mg/L RbCl; 0.02261 mg/L SrCl2; 0.004 mg/L NaBr; 0.01341 mg/L Na2MoO4; 0.00336 mg/L CuCl2; 0.013 mg/L ZnCl2; 0.00546 mg/L CoCl2; 0.00325 mg/L KJ; 0.00219 mg/L Na2SeO3; 0.00058 mg/L NH4VO3; 0.56456 mg/L Na2EDTA and 0.13608 mg/L FeSO4.

OTHER TEST CONDITIONS
- Adjustment of pH: The pH of the stock solution (ca. 4) was adjusted to ca. pH 8 with NaOH. The pH was assessed on Day 0, 2, 5, 8, 12, 14, 16, 19 and 21.
- Photoperiod: Day: Night-rhythm, 16:8 hours
- Light intensity: ca. 1 000 lux (white flourescent tube)

EFFECT PARAMETERS MEASURED
- Mortality, reproduction and other observations.
- Daphnia were evaluated on Day 0, 1, 2, 5, 6, 8, 9, 10, 12, 13, 14, 15, 16, 19, 20, 21 and 22.

TEST CONCENTRATIONS
- Test concentrations: Based on the results of an acute test

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

other: LC0

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

The data indicate a low toxicity of the test material to daphnids. At the lower concentrations (up to 25 mg/L) there seems to be a slight tendency for stimulating and at 50 mg/L for inhibitory effects on reproduction. However, a statistically significant effect (p < 0.05) on reproduction was only observed at the highest test concentration, 100 mg/L, which caused a 43 % reduction in the no. of live offspring.
The tested concentration of the test material (up to 100 mg/L) caused no significant mortality of the parent daphnids.
At the highest concentration (100 mg/L) next to a reduction in the number of live offspring some offspring appeared dead and also aborted eggs were observed.
NOEC = 50 mg/L
LOEC = 100 mg/L
LC0 = 100 mg/L
The results are based on nominal concentrations as a concentration control analysis study revealed satisfactory agreement between nominal and measured data.

Reported statistics and error estimates:

For the calculation of the reproduction, only living offspring or parents surviving to the end of the experiment were considered.
The average number of offspring per parent in each concentration and the coefficient of variation (cv) are calculated.
The NOEC is determined statistically (p < 0.05) via an analysis of variance followed by a Dunnett's test. The calculations are carried out with a PC and the software "RS/1". The LOEC is the concentration above the NOEC, taking into account that the reproductive inhibition at test concentrations above the LOEC should at least be equal or greater than the calculated LOEC.
The LC0 (with respect to parent mortality) can either be determined directly from the data or a statistical analysis as described above (Dunnett's test) should be applied.
If the data are sufficient (i.e. if the reproductive inhibition is large enough over several concentrations) the EC50 can be determined mathematically by probit analysis. If possible (depended on the degrees of freedom) 95 % confidence limits are given.

Average Numbers of Offspring, Variation, and Mortalities at Different Concentrations of Test Material

Parameter	Concentration (mg/L)
	0	1	2.5	10	25	50	100
Offspring (average number)	88	93	99	94	99	74	50
CV (%)	18	21	14	10	5	21	28
Mortality (no.) of parent (before Day 21)	0	0	0	0	0	0	0

 

Validity Criteria

The validity criteria < 10 % mortality of parents in the control, > 3 mg/L dissolved oxygen, > 60 offspring/ parent in the control after 21 days, coefficient of variation < 26 %, first offspring after 9 days - are fulfilled in this test.

Analysis of Variance

	DF	SS	MS=SS/DF	F Value	Sign level
Factor	6	19086.49	3176.08	15.62	0
Error	63	12808.60	203.31
Total	69	31865.09

The null hypothesis that the samples come from populations with equal means can be rejected (P = 0).

 

Dunnett’s Multiple Comparison Test

Alternative Hypothesis	Diff. in Means	Standard Error	Observed Statistics	Critical Value	Signif. Level
Contr. < > 100	38.2	6.377	5.991	2.64	P ≤ 0.05
Contr. < > 50	13.8	6.377	2.164	2.64	P > 0.05
Contr. < > 25	11.2	6.377	1.756	2.64	P > 0.05
Contr. < > 2.5	10.9	6.377	.709	2.64	P > 0.05
Contr. < > 10	6.1	6.377	0.957	2.64	P > 0.05
Contr. < > 1	5.0	6.377	0.784	2.64	P > 0.05

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the study significant effects on the reproduction of Daphnia magna after 21 days could only be observed at the highest concentration of the test material, 100 mg/L.
The test material caused no mortality up to the highest concentration, 100 mg/L. The LOEC was 100 mg/L; the NOEC was 50 mg/L and the LC0 was 100 mg/L (nominal concentrations, measured values being > 80 % of nominal).

Executive summary:

The effect of the test material on daphnia reproduction was assessed according to OECD Test Guideline 202 and in compliance with GLP for 21 days under semi-static conditions at nominal concentrations of 0, 1, 2.5, 10, 25, 50, 100 mg/L.

The data indicate a low toxicity of the test material to daphnids. At the lower concentrations (up to 25 mg/L) there seems to be a slight tendency for stimulating and at 50 mg/L for inhibitory effects on reproduction. However, a statistically significant effect (p < 0.05) on reproduction was only observed at the highest test concentration, 100 mg/L, which caused a 43 % reduction in the number of live offspring.

The tested concentration of the test material (up to 100 mg/L) caused no significant mortality of the parent daphnids.

At the highest concentration (100 mg/L) next to a reduction in the number of live offspring some offspring appeared dead and aborted eggs were also observed.

The results are based on nominal concentrations as a concentration control analysis study revealed satisfactory agreement between nominal and measured data.

Under the conditions of the study the NOEC was 50 mg/L and the LOEC was 100 mg/L. The LC0 was 100 mg/L.

Description of key information

Dohmen (1993)

Under the conditions of the study significant effects on the reproduction of Daphnia magna after 21 days could only be observed at the highest concentration of the test material, 100 mg/L.

The test material caused no mortality up to the highest concentration, 100 mg/L.  The LOEC was 100 mg/L; the NOEC was 50 mg/L and the LC0 was 100 mg/L (nominal concentrations, measured values being > 80 % of nominal).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

50 mg/L

Additional information

Dohmen (1993)

The effect of the test material on daphnia reproduction was assessed according to OECD Test Guideline 202 and in compliance with GLP for 21 days under semi-static conditions at nominal concentrations of 0, 1, 2.5, 10, 25, 50, 100 mg/L. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The data indicate a low toxicity of the test material to daphnids. At the lower concentrations (up to 25 mg/L) there seems to be a slight tendency for stimulating and at 50 mg/L for inhibitory effects on reproduction. However, a statistically significant effect (p < 0.05) on reproduction was only observed at the highest test concentration, 100 mg/L, which caused a 43 % reduction in the number of live offspring.

The tested concentration of the test material (up to 100 mg/L) caused no significant mortality of the parent daphnids.

At the highest concentration (100 mg/L) next to a reduction in the number of live offspring some offspring appeared dead and aborted eggs were also observed.

The results are based on nominal concentrations as a concentration control analysis study revealed satisfactory agreement between nominal and measured data.

Under the conditions of the study the NOEC was 50 mg/L and the LOEC was 100 mg/L. The LC0 was 100 mg/L.