Mecoprop

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please see the read-across justification report in Section 13 of the dossier.

Reason / purpose for cross-reference:

read-across source

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

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).

Considering the very close structural similarity between the source and target substances (as justified in the read-across report that is attached to section 13 of the dossier), results from the study performed with mecoprop-p can be extrapolated to mecoprop.

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.

 

 

Findings from the study conducted with the read-across substance are viewed as representing a 'worst case' scenario bearing in mind it is information on the read-across substance that is driving the environmental classification of the registered substance. Hence relying on information on the read-across substance is viewed as representing a conservative approach to risk assessment of the registered substance.

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 March 1989 to 07 June 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Test Guideline: Prolonged toxicity study with Daphnia magna: Effects on reproduction. EEC-DG XI, Doc. XI/681/86

Version / remarks:

Draft 4 (September 1986)

Deviations:

no

Principles of method if other than guideline:

20 animals per test concentration were used instead of 10

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 4.6, 10, 21, 46, 100 mg/L
- Sampling method: The concentration of the test material was determined in freshly prepared and old medium on four days during the first run of the test.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test material is poorly water soluble and its presence in water causes a change of the pH, which is outside the range that can be supported by the test animal, therefore DMA is added. The stock solution of 1 g/L was prepared by addition of the test material to water to which Dimethylamine (DMA) was added. The dispersion was treated by ultra-sonification for 15 to 30 minutes. The resulting stock solution was neutralised with DMA.
- Other relevant information: The range of test concentrations chosen were based of the acute tests for Daphnia with the test material. The chosen concentrations were prepared by dilution of the stock solution.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia Magna
- Age at study initiation: 24 Hours old
- Feeding during test: Yes, Daphnia were fed on days 0, 2, 5, 7, 9, 12, 14, 16, 19 and 21 in test 1. In test two they were fed on all days apart from day 1, 4, 11, 18 and 21.
- Food type: Fed with living Chlorella cells
- Amount: In test one, between 50 and 300 µL of the cell suspension was added to each test vessel. In test two, between 50 to 200 µL of the cell suspension was added.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

70 mg Ca/L, 20 mg Mg/L, 15 °dH

Test temperature:

19 to 20 °C

pH:

7.5 to 7.9

Dissolved oxygen:

8 to 10 mg/L of O2

Nominal and measured concentrations:

Nominal concentrations: For the first test: 4.6, 10, 21, 46 and 100 mg/L.
Second test: 0.46, 1, 2.1, 4.6, 10 and 21 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Beakers
- Material, size, headspace, fill volume: Polystyrene beaker (50 mL)
- Renewal rate of test solution: Medium is replaced three times a week, at renewal, the animals are transferred to freshly prepared test medium
- No. of organisms per vessel: 1. In the second test, animals were initially kept in a larger group in a 1 litre beaker and transferred to smaller containers on day 5.
- No. of vessels per concentration: 20
- No. of vessels per control: 20

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The natural water in which the animals were cultures was also used as dilution water for the study. Source was a large turtle tank which was purified by a biological filtration system including a mechanical filter, an aerobic sprinkling filter and an anaerobic nitrate removal - Minireef System)
- Ca/mg ratio: 3.5 :1

OTHER TEST CONDITIONS
- Adjustment of pH: DMA was used to neutralise the the stock solution. pH values were measured in the control and in the test concentrations in the fresh and old medium
- Photoperiod: 16 hours artificial light per day

EFFECT PARAMETERS USED:
- Reproduction, mortality, time to production of first brood.

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality: Number of living offspring produced per surviving parental animal {for Daphnia magna, TG 211}

Details on results:

REPRODUCTION AND SURVIVAL:
The results on reproduction and survival are summarised in the Table below. The mean reproduction per surviving female was calculated over 21 days.
In the first test, the reproduction was inhibited almost completely at 100 mg Test material/L. At lower concentrations, a partial inhibition was observed, but a concentration without effect was not found. The mortality in the controls was higher than allowed in the guideline. Therefore, the test was repeated with lower concentrations. The second run confirmed the findings of the first test: at 21 mg/L a partial inhibition occurred, and again a NOEC could not be established, implying that reproduction is inhibited in the range of 0.46 to 100 mg/L. Again, the mortality in the control was too high.

OTHER OBSERVATIONS:
The time to production of first brood did not seem to be affected in 0.46 mg/L, whereas in all higher concentrations, the production of the first brood was retarded as compared to the control. The parents in 100 mg/L were smaller than in lower concentrations.

Table showing the effect of the test material on the survival and reproduction of Daphnia magna 

 

Con. test material (mg/L)	Mortality			Reproduction
Test 1 (29/03/89)	Day 1-5 (%)	Day 6-21 (%)		X	s.d	c.v
Control I	0	25		110	19	0.17
Control II*	0	21		121	17	0.14
4.6	0	15		54	29	0.53
10	0	20		45	23	0.52
21	0	20		28	20	0.72
46	0	30		29	28	1
100	0	30		7	5	0.77
Test 2 (17/05/1989)
Control III	3	30		122	22	0.18
Control IV**	0	45		96	38	0.4
0.46	3	40		66	34	0.52
1	7	20		68	26	0.38
2.1	3	35		68	35	0.51
4.6	7	35		65	17	0.26
10	0	35		65	29	0.44
21	0	20		68	31	0.4

*: Control II belongs to a test carried out simulataneously.

**: Control IV belongs to the 21 and part of the 10 mg/L groups 

S.d: Standard deviation

C.v: Coefficient of variation

 

Validity criteria:

The proposed EEC Guideline proposes several physical/chemical and biological validity criteria for the test:

1. The concentration of oxygen should be above 2 mg/L. This criterion was met in all cases.


2. The mortality of the parent animals at the end of the test must be =< 10 %. This criterion was not met in either of the two tests.


3. The coefficient of variation around the mean number of offspring per parent animal was less than 25 % in the relevant controls.

The tests were not performed with 10 animals as required by the proposed guideline, but with 20 animals per test concentration. Therefore, in spite of the higher mortality, a sufficient number of animals and reproduction data remained
available for valid interpretation of the test results.

 

Mortality:

During the first test mortality was relatively high. In the highest concentration, however, the reproduction was very low and at the same time, survival was high. Therefore, the mortality in the lower concentrations in the control seemed to be the "cost" of a high reproduction rate. This is confirmed by the observation that mortality occurred mainly towards the end of the test, on day 19. In the second test, mortality was spread more evenly over the whole period. A concentration-dependency of the mortality could not be detected. The NOEC for mortality after 21 days is higher than 100 mg/L, whereas the NOEC for immobility in the acute tests was 320 mg/L. Therefore, it is concluded that an elongation of the exposition period does not decrease the NOEC for mortality.

 

Repoduction:

A partial inhibition of the reproduction was observed over a wide range of concentrations (0. 46 to 46 mg/L), and a good concentration-effect relationship could not be established. This implies that the two parameters survival and reproduction differ in their sensitivity by a relatively high factor of (>100 / <0.46 =) > 217. The inhibition of the reproduction was between 25 and 55% over the whole range. This rather unusual effect might be caused by the presence of a poorly water-soluble impurity in the test material sample, which consisted of a mixture, containing a number of specified impurities. A poorly water-soluble impurity would then be present in approximately the same concentration, in all test concentrations. If this impurity is toxic at its saturation value, it could cause similar inhibitory effects. If this might be the case, the test should not be repeated with this sample, but with another, more purified one.

Validity criteria fulfilled:

no

Remarks:

Mortality was not less than 10 %, however 20 animals per test concentration were used deviating from the test guideline. In spite of a higher mortality, a sufficient number of animals remained available for valid interpretation of test results

Conclusions:

Under the conditions of this study, the No Observed Effect Concentration (NOEC) for mortality (living offspring per surviving parent animal) was found to be higher than 100 mg/L which was the highest concentration used in the study. The NOEC for reproduction could not be established.

Executive summary:

The long-term toxicity of the test material to Daphnia magna was assessed according to EEC Test Guideline (1986) ‘"Test Guideline Prolonged Toxicity Study with Daphnia magna: Effects on Reproduction" and in compliance with GLP.

Young female Daphnia, aged less than 24 hours, were exposed to the test material added to water at a range of concentrations over a period of 21 days. At the end of this period the mean number of living offspring per surviving parent animal in each of the test concentrations was compared to the mean in the control and the NOEC (no observed effect concentration) was determined. Other relevant effects, e.g., mortality of parent animals and delayed production of the first brood, were also recorded. In acute tests, the NOEC for mortality and immobility was 320 mg test material/L. In the prolonged test with 100 mg/L as the highest concentration, no increased mortality was observed. The reproduction was partially inhibited over a large range of concentrations: from 0.46 to 46 mg/L, and the reproduction was approximately 55 to 25 % of reproduction in the control. The reproduction was inhibited almost completely in 100 mg/L and a NOEC for reproduction could not be established.

Under the conditions of this study, the No Observed Effect Concentration (NOEC) for mortality (living offspring per surviving parent animal) was found to be higher than 100 mg/L which was the highest concentration used in the study. The NOEC for reproduction could not be determined.

Reference 3

Endpoint:

long-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:

25 daphniae were exposed for a period of 3 weeks. The new-born daphniae were separated from their mothers twice a week and counted.

GLP compliance:

no

Remarks:

Study pre-dates GLP.

Analytical monitoring:

yes

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: 6 to 24 hours old
- Age of parental stock (mean and range, SD): Born of 3 weeks old mothers.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 wk

Nominal and measured concentrations:

The concentrations tested were a control, 0.01 x LC50, 0.032 x LC50, 0.1 x LC50, 0.32 x LC50 and the LC50, as determined in the acute toxicity test for water fleas.

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 litre aquaria
- No. of vessels per concentration: Duplicate
- To each concentration 25 daphniae were added.
- Renewal: The new-born daphniae were separated from their mothers twice a week and counted. At the same time the solutions were completely replaced.

EFFECT PARAMETERS MEASURED
- The mortality also was recorded and the LC50 determined according to Litchfield and Wilcoxon 1949.
By plotting the number of juveniles per daphnia after three weeks against the logarithm of the concentration of test material, the EC50 was determined.

Duration:

3 wk

Dose descriptor:

EC50

Effect conc.:

440 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 250 - 780 mg/L

Key result

Duration:

3 wk

Dose descriptor:

EC50

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the test the EC50 for daphnia reproduction was 100 mg/L.

Executive summary:

The effects of the test material on daphnia reproduction was assessed over 3 weeks exposure. The new-born daphniae were separated from their mothers twice a week and counted.

Under the conditions of the test the EC50 for daphnia reproduction was 100 mg/L.

Description of key information

Key Study: Balk (1989)

Under the conditions of this study, the No Observed Effect Concentration (NOEC) for mortality (living offspring per surviving parent animal) was found to be higher than 100 mg/L which was the highest concentration used in the study. The NOEC for reproduction could not be determined.

 

 

Key study: Dohmen (1993) - Read across (MCPP-P)

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).

 

Supporting Study: ten Berge (1978)

Under the conditions of the test the EC50 for daphnia reproduction was 100 mg/L.

 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

50 mg/L

Additional information

Key Study: Balk (1989)

The long-term toxicity of the test material to Daphnia magna was assessed according to EEC Test Guideline (1986) ‘"Test Guideline Prolonged Toxicity Study with Daphnia magna: Effects on Reproduction" and in compliance with GLP. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Young female Daphnia, aged less than 24 hours, were exposed to the test material added to water at a range of concentrations over a period of 21 days. At the end of this period the mean number of living offspring per surviving parent animal in each of the test concentrations was compared to the mean in the control and the NOEC (no observed effect concentration) was determined. Other relevant effects, e.g., mortality of parent animals and delayed production of the first brood, were also recorded.

In acute tests, the NOEC for mortality and immobility was 320 mg test material/L. In the prolonged test with 100 mg/L as the highest concentration, no increased mortality was observed. The reproduction was partially inhibited over a large range of concentrations: from 0.46 to 46 mg/L, and the reproduction was approximately 55 to 25 % of reproduction in the control. The reproduction was inhibited almost completely in 100 mg/L and a NOEC for reproduction could not be established.

Under the conditions of this study, the No Observed Effect Concentration (NOEC) for mortality (living offspring per surviving parent animal) was found to be higher than 100 mg/L which was the highest concentration used in the study. The NOEC for reproduction could not be determined.

 

Key study: Dohmen (1993) - Read across (MCPP-P)

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.

 

The NOEC from this study was taken forward for risk assessment as it represents the most conservative approach.

 

 

Supporting Study: ten Berge (1978)

The effects of the test material on daphnia reproduction was assessed over 3 weeks exposure. The new-born daphniae were separated from their mothers twice a week and counted.

Under the conditions of the test the EC50 for daphnia reproduction was 100 mg/L.