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Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted according to GLP requirements and in line with OECD test method. Study is well documented and the data complete.
Qualifier:
no guideline available
Guideline:
OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)
Version / remarks:
Aspects of this guideline were taken into account.
Principles of method if other than guideline:
The study was conducted in order to determine the potential impact of the test item on the survival, reproduction and biomass of the aquatic oligochaete Lumbriculus variegatus at the end of the exposure phase. The design of this study takes into account aspects of OECD Draft Guideline 218: "Sediment-Water Chironomid Toxicity Test Using Spiked Sediment (OECD 2002)".
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
The test concentrations were measured on day 0, 9, 19 and 28of the 26.5 and 140 mg/kg sediment dw (nominal) samples.
Vehicle:
yes
Details on sediment and application:
Test item dissolved in acetone; test item coated on quartz sand, then mixed with wet sediment
Test organisms (species):
Lumbriculus variegatus
Details on test organisms:
The test system used in this study is the endobenthic oligochaete Lumbriculus variegatus (Müller). This species is tolerant to a wide range of sediment types, and is widely used for sediment toxicity and bioaccumulation testing. The species has been cultured at ECT Oekotoxikologie GmbH since Jan. 1998. The animals were originally obtained from Fischfutter Etzbach (D-53894 Mechernich-Bergheim, Germany). The species identity of the cultured organisms was confirmed according to Brinkhurst (1971).
Study type:
laboratory study
Test type:
static
Water media type:
freshwater
Type of sediment:
artificial sediment
Limit test:
no
Duration:
28 d
Exposure phase:
total exposure duration
Hardness:
Water Hardness used for the test on day -7 [mg/l as CaCO3]: 235
Test temperature:
20.6 - 21.5°C
pH:
Reconstituted water: 8.34-8.49 (mean of all samples)
Dissolved oxygen:
Reconstituted water: 8.00-8.68 mg/l (mean of all samples)
Ammonia:
0.9-1.16 mg/l (mean for all concentrations)
Nominal and measured concentrations:
Test concentrations: 140.0, 60.9, 26.5, 11.5 and 5.0 mg/kg sediment dry weight plus a solvent control and a control.
Number of replicates per treatment: 6 in the controls; 4 in each other treatment; additional vessels for chemical analysis.
Measured concentrations for the 26.5 and 140 mg/kg sediment dw nominal samples were 16 and 79 mg/kg sediment dw respectively.
Details on test conditions:
Overlying water: reconstituted water according to OECD guideline No. 203 (OECD 1992); sediment water ratio approx. 1 : 4
Control media: uncontaminated artificial sediment and reconstituted water.
Sediment conditioning: 7 d prior to application of test item.
Sediment spiking: test item dissolved in acetone; coated on quartz sand; then mixed with wet sediment.
Test medium: spiked artificial sediment according to OECD draft guideline No. 218 (OECD 2002); peat content 5% of sediment d.w.; addition of urtica-powder (0.25% on dry sediment) and cellulose-powder (0.25% on dry sediment) before application of test item.
Equilibration: 7 d prior to addition of organisms.
16 hours light (intensity 313-446 lux) and 8 hours dark.
The total organic carbon content (TOC) of the sediment directly after preparation of the presediment on day -14 of the test was determined to be 2.06 ± 0.02% (average ± standard deviation) of sediment dry weight.
Reference substance (positive control):
no
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
11.5 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
on the basis of dry biomass per replicate
Duration:
28 d
Dose descriptor:
LOEC
Effect conc.:
26.5 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
on the basis of dry biomass per replicate
Duration:
28 d
Dose descriptor:
other: EC15
Effect conc.:
19.4 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
on the basis of dry biomass per replicate
Remarks on result:
other: 95% CL: 16.5-31.6 mg/kg sediment dw
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
120.6 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
on the basis of dry biomass per replicate
Remarks on result:
other: 95% CL: 81.1-254.2 mg/kg sediment dw
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
26.5 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
28 d
Dose descriptor:
LOEC
Effect conc.:
60.9 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
28 d
Dose descriptor:
other: EC15
Effect conc.:
26.4 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: 95% CL: 11.0-39.1 mg/kg sediment dw
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
87.2 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: 95% CL: 65.1-128.9 mg/kg sediment dw
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
> 140 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Reported statistics and error estimates:
Normal distribution of data was tested with the Kolmogorov-Smirnov goodness-of-fit test (two sided, p ≤ 0.05). Cochran´s test (two-sided, p ≤ 0.05) was used to test variance homogeneity. One-way Analysis of Variance (ANOVA) and subsequent multi-comparison tests (Dunnett’s Test; one-sided, smaller) were used to calculate whether there were significant differences (p ≤ 0.05) between the controls and the various test item concentrations.
To determine significant differences between the controls (control and solvent control) the replicates of each control were tested for normal distribution homogeneity (Kolmogorov-Smirnov-test) and for homogeneity of variances (Cochran´s test); thereafter a pair wise comparison test (Student-t Test or Welch T-test) were used. If these tests detected no significant differences, all control and solvent control replicates were pooled.
The ECx were calculated using linear regression analysis (Probit).

Survival

After 28 days of exposure, no dead and missing worms were observed. The parameter survival was not affected up to the highest concentration level, therefore no LCx could be calculated.

Reproduction

The total number of worms (including adult and regenerated worms) found at the end of the test was evaluated as parameter of reproduction and the results are displayed in table 1.

Table 1 Total number of worms per treatment after 28 days of exposure.

Concentration
AHTN[mg/kg sed. dw] mean sd
0 control 29.8 2.2
0 solvent control 27.0 3.7
5.0 31.5 3.7
11.5 29.3 1.5
26.5 25.0 7.0
60.9 16.3 3.5
140.0 10.8 1.0

sd: standard deviation

Biomass

The impact of AHTN on the biomass has also been invetsigated and the results can be found in table 2

Table 2 Total biomass of the animals of each treatment in mg dry weight.

Concentration
AHTN [mg/kg sed dw] mean sd
0 control 26.6 3.3
0 solvent control 29.2 2.4
5.0 26.5 2.9
11.5 24.2 3.5
26.5 22.2 3.2
60.9 19.5 1.5
140.0 12.0 1.4

sd: standard deviation

Validity criteria fulfilled:
yes
Remarks:
see overall remarks
Conclusions:
The sediment toxicity of AHTN was assessed in a 28d study with the aquatic oligochaete worm Lumbriculus variegatus in line with OECD TG 218. The organic carbon content in the medium was 2.06%. No mortality was observed up to the highest concentration level of 140 mg AHTN/kg sediment dry weight (NOEC>140 mg/kg dw). The reproduction and biomass the test showed a clear dose-response relationship. The NOEC was 11.5 mg/kg dw for biomass and 26.5 for reproduction. Based on measured concentrations, the lowest NOEC(biomass) is 7.1 mg/kg dw.
Executive summary:

A toxicity test was carried out with the Lumbriculus variegatus using sediment that was formulated from 5% Sphagnum moss peat, 75% quartz sand (>50% in range 50-200μm), 20% kaolinite clay and 0.05% calcium carbonate to adjust the pH between 6.5 and 7.0.

At the same time 0.2-0.25% Urtica andα-cellulose powder was added as feed. The formulated sediment was conditioned for 7 days prior to application of the test material. The test material was solved in acetone to prepare the stock solutions for each concentration. The proper volumes were mixed first with dry quartz sand allowing the solvent to evaporate. Next the sand was mixed with the formulated sediment to achieve the intended nominal concentration levels. Each glass vessel contained a layer of 1.5 to 3 cm of sediment and the water (Elendt medium M4) volume was 3.5 to 4.5 times the sediment volume.

The test animals were introduced after an equilibration period of 1 week. The tests were carried out at 20ºC under a 16/8 hours L/D cycle. The overlying water was slightly aerated during the test. No additional food was given during the test.

The test medium contained 2.06% organic carbon.

Test concentrations were measured. Samples of porewater and overlying water were extracted by SPE using Speedisks. Sediment samples were freeze-dried and analysed by GC/MS after solvent extraction.The results are reported by Belfroid and Balk (2005).

Spiked artificial sediment and reconstituted water were used in the test with nominal AHTN concentrations of 140.0, 60.9, 26.5, 11.5 and 5.0 mg/kg sediment dry weight plus a solvent control and a control. The end points that were determined were survival, reproduction, and biomass. Survival was not affected up to the highest AHTN concentration of 140 mg/kg sediment dry weight, which is the NOEC for this end point. With respect to biomass and reproduction the test showed a clear dose-response relationship. The NOEC and EC50 for reproduction were 26.5 and 87.2 mg/kg sediment dw respectively, while these parameters for biomass were 11.5 and 120.6 mg/kg sediment dw. However, the lowest NOEC (biomass) was 11.5 mg/kg, which was corrected to 7.1 mg/kg sediment dw on the basis of recovery experiments.

Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
6 April - 16 November 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted according to GLP requirements and in line with OECD test method. Study is well documented and the data complete.
Qualifier:
according to
Guideline:
OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)
Principles of method if other than guideline:
For this study no standard guideline is available. The design of this study takes into account aspects of OECD Draft Guideline 218: "Sediment-Water Chironomid Toxicity Test Using Spiked Sediment (OECD 2002)".
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
The test concentrations were measured on day 0, 9, 19 and 28 in the control, 29 and 140 mg/kg.
Vehicle:
no
Details on sediment and application:
The sediment was formulated from 5% Sphagnum moss peat, 75% quartz sand (>50% in range 50-200 μm), 20% kaolinite clay and 0.05% calcium carbonate to adjust the pH between 6.5 and 7.1. The organic carbon content was 2%. At the same time 0.2-0.25% Urtica powder was added as feed. The formulated sediment was conditioned for 7 days prior to application of the test material.
Test organisms (species):
Hyalella azteca
Details on test organisms:
The test animals were 7 to 14 days old, and between 355 and 500 mm.
Study type:
laboratory study
Test type:
static
Water media type:
freshwater
Type of sediment:
artificial sediment
Limit test:
no
Duration:
28 d
Exposure phase:
total exposure duration
Hardness:
Water hardness was measured before introducing test organisms, and on day 28 of the test. The values determined ranged between 19.2 and 23.0 [°dH], i.e. 341.8 and 409.4 mg/l as CaCO3.
Test temperature:
Temperature in the test vessels is 20.4-20.7°C.
pH:
pH values in the overlying water is 8.3-8.5.
Dissolved oxygen:
Mean oxygen concentrations [mg/l] is 8.7-9.0
Ammonia:
Mean ammonium content (as NH4+) in the overlying water is 2.0-3.2 mg/l
Nominal and measured concentrations:
Nominal: 140.0, 63.6, 28.9, 13.1, 6.0 mg/kg sediment (dry weight).
Details on test conditions:
The test was carried out at 20 ºC under a 16/8 hours L/D cycle with a light intensity of 400 to 600 lux.
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
18.2 mg/kg sediment dw
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
and mortality
Remarks on result:
other: Sediment contained 2.15% organic carbon. Concentration measured on day 0 at NOEC: 18.2 mg/kg. During the test the concentration remained at this level.
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
28.9 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
and mortality
Duration:
28 d
Dose descriptor:
LOEC
Effect conc.:
63.6 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks:
and mortality
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
57.6 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: biomass
Remarks on result:
other: 95% CL 45.7 - 72.4

At the start of the test the test concentration was on average 66% of the intended nominal test concentration. At termination of the test, the average concentration was 92% of the concentration at the start. Survival was not affected up to 29 mg/kg, whereas the mortality in 64 mg/kg was 28% and 98% in 140 mg/kg. Thus the LC50was 77.3 68 – 87> mg/kg. Growth was inhibited at 64 mg/kg (LOEC). The length of the amphipods was 15% below the pooled control at 64 mg/kg, whereas the (total) biomass per replicate and the individual biomass were 54% and 38% below the control, respectively. At 29 mg/kg the inhibition was 3.5% for length and 15% for biomass. The EC15 for total biomass was 30.2 15.9 – 39.6> mg/kg, the EC50 was 57.6 45.7 – 72.4> mg/kg. The actual concentration on day 0 at the NOEC level was measured: 18.2 mg/kg. During the test, the concentration remained at this level. Thus 18.2 mg/kg dwt is considered as the NOEC in this study.

Validity criteria fulfilled:
yes
Conclusions:
A toxicity test was carried out with the Amphipoda Hyalella azteca in accordance with OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment). The organic carbon content in the sediment was 2.15%. The actual concentration on day 0 at the NOEC level (28.9 mg/kg) was measured: 18.2 mg/kg. During the test the concentration remained at this level (92%). Thus 18.2 mg/kg dwt is considered as the NOEC in this study.
Executive summary:

A toxicity test was carried out with the Amphipoda Hyalella azteca in accordance with OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment). The sediment was formulated from 5% Sphagnum moss peat, 75% quartz sand (>50% in range 50-200μm), 20% kaolinite clay and 0.05% calcium carbonate to adjust the pH between 6.5 and 7.1.

 

At the same time 0.2-0.25% Urtica powder was added as feed. The formulated sediment was conditioned for 7 days prior to application of the test material. The test material was solved in acetone to prepare the stock solutions for each concentration. The proper volumes were mixed first with dry quartz sand allowing the solvent to evaporate. Next the sand was mixed with the formulated sediment to achieve the intended nominal concentration levels. Each glass vessel contained a layer of 1.5 to 3 cm of sediment and the water (Elendt medium M4) volume was 3.5 to 4.5 times the sediment volume. Both a control and a solvent control were included. The test animals were introduced after an equilibration period of 1 week. The tests were carried out at 20 ºC under a 16/8 hours L/D cycle with a light intensity of 400 to 600 lux. The overlying water was slightly aerated during the test. No additional food was given during the test. Test concentrations were measured. Samples of porewater and overlying water were extracted by SPE using Speedisks. Sediment samples were freeze-dried and analysed by GC/MS after solvent extraction. The results are reported by Belfroid and Balk (2005). The Amphipoda Hyalella azteca was tested in five concentrations ranging from 6 to 140 mg/kg sediment with step size 2.2. The test animals were 7 to 14 days old, and between 355 and 500 mm. Four replicates each with 10 animals were used per test concentration and in the solvent control, whereas six replicates were used in the control. The test concentrations were measured on day 0, 9, 19 and 28 in the control, 29 and 140 mg/kg.

 

The test was carried out in a substrate containing 2.15 % organic carbon.

 

At the start of the test the test concentration was on average 66% of the intended nominal test concentration. At termination of the test, the average concentration was 92% of the concentration at the start. Survival was not affected up to 29 mg/kg, whereas the mortality in 64 mg/kg was 28% and 98% in 140 mg/kg. Thus the LC50was 77.3 68 – 87> mg/kg. Growth was inhibited at 64 mg/kg (LOEC). The length of the amphipods was 15% below the pooled control at 64 mg/kg, whereas the (total) biomass per replicate and the individual biomass were 54% and 38% below the control, respectively. At 29 mg/kg the inhibition was 3.5% for length and 15% for biomass. The EC15 for total biomass was 30.2 15.9 – 39.6> mg/kg, the EC50 was 57.6 45.7 – 72.4> mg/kg. The actual concentration on day 0 at the NOEC level was measured: 18.2 mg/kg. During the test the concentration remained at this level. Thus 18.2 mg/kg dwt is considered as the NOEC in this study.

Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 february - 16 November 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted according to GLP requirements and OECD test method. Study is well documented and the data complete.
Qualifier:
according to
Guideline:
OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
Four replicates each with 20 organisms were used per test concentration and in the solvent control and control.
The AHTN concentrations in sediment, the porewater and overlying water were measured on day 0, 9, 19 and 28 for the 125 and 1000 mg/kg sediment dw.
Vehicle:
yes
Details on sediment and application:
The sediment was formulated from 5% Sphagnum moss peat, 75% quartz sand (>50% in range 50-200 μm), 20% kaolinite clay and 0.05% calcium carbonate to adjust the pH between 6.5 and 7.0. The organic carbon content was 2%. At the same time 0.2-0.25%. Urtica powder was added as feed. The formulated sediment was conditioned for 7 days prior to application of the test material. The test material was solved in acetone to prepare the stock solutions for each concentration. The proper volumes were mixed first with dry quartz sand allowing the solvent to evaporate. Next the sand was mixed with the formulated sediment to achieve the intended nominal concentration levels. Each glass vessel contained a layer of 1.5 to 3 cm of sediment and the water (Elendt medium M4) volume was 3.5 to 4.5 times the sediment volume. Both a control and a solvent control were included. The test animals were introduced after an equilibration period of 1 week. The overlying water was slightly aerated during the test. No additional food was given during the test.
Test organisms (species):
Chironomus riparius
Details on test organisms:
Chironomus riparius (Meigen) 1st instar larvae.
20 organisms per test chamber and 4 replicates.
Study type:
laboratory study
Test type:
not specified
Water media type:
freshwater
Type of sediment:
artificial sediment
Limit test:
no
Duration:
28 d
Exposure phase:
total exposure duration
Hardness:
Water hardness was measured before introducing the test organisms, and on day 28 of the test. The values determined ranged between 18.8 and 23.4 [°dH], i.e. 334.6 and 416.5 mg/l as CaCO3.
Test temperature:
20.0 – 21.6°C (46 measurements)
pH:
The pH of the overlying water ranged between 7.8 and 8.5.
Dissolved oxygen:
>74% of air saturation value
Ammonia:
Control 4.8; Solvent control 6.05 and samples 4-6 mg/l NH4 of overlaying water. The measured ammonium is assumed to originate from the organic components of the sediment (peat, cellulose and urtica powder), where the nitrogen-rich urtica powder is considered to contribute a major portion of the measured ammonium. The ammonium concentration increases to a certain peak level, whereafter the ammonium decreases. These changes in the ammonium concentrations over the course of the test are presumably due to the presence and the varying quantity of nitrifying microflora in the test system.
Baswed on historical data ,the temporarily elevated ammonium concentration is not assumed to have an influence on the performance of the test organisms.
Nominal and measured concentrations:
1000, 500, 250, 125, 62.5 mg/kg sediment dry weight plus a solvent control and a control.
On day 0, the measured concentration of the nominal 125 mg/kg sediment dry weigh was 100 mg/kg sedient dw. and the 1000 mg/kg sediment dw was 930 mg/kg sediment dw.
Details on test conditions:
Sediment conditioning: 7 d prior to application of test item.
Sediment spiking: test item dissolved in acetone; coated on quartz sand; then mixed with wet sediment.
Equilibration: 7 d prior to addition of organisms.
Light regime: 16h light (Light intensity: 506.4 lux) and 8h dark.
The pH as measured in the sediment on day -7 was 6.5 ± 0.1 (SD).
The Total Organic Carbon (TOC) of the sediment as measured directly after preparation of the pre-sediment on day -14 of the test was determined to be 2.42 ± 0.06%.
Reference substance (positive control):
no
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
101 mg/kg sediment dw
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
development rate
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
125 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
development rate
Duration:
28 d
Dose descriptor:
LOEC
Effect conc.:
250 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
development rate
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
500 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
emergence rate
Duration:
28 d
Dose descriptor:
LOEC
Effect conc.:
1 000 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
emergence rate
Duration:
28 d
Dose descriptor:
other: EC15
Effect conc.:
549 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
emergence rate
Remarks on result:
other: 95% CL: 472-639 mg/kg sediment dw
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
785 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
emergence rate
Remarks on result:
other: 95% CL: 714-862 mg/kg sediment dw
Details on results:
After the equilibrium period at the start of the test the concentration was on average 87% of the intended nominal test concentration. At termination of the test, the average concentration was 67% of the concentration at the start.
Reported statistics and error estimates:
Probit analysis, ANOVA and multiple comparison tests (Dunnett's t-test, Welch t-test)
The pair-wise comparison of solvent control with the control (ER) by the t-test procedure showed no significant differences between the means of males and females. Therefore an influence of the solvent used to apply the test item to the sediment on the emergence of the midges could be excluded.
At 1000 mg/kg sediment d.w., no female midges emerged. The Chi2 r-x-2-table test showed a significant effect (p = 0.05). Therefore the parameter development rate (DR) was evaluated separately for male and female emerged midges.
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Emergence ratio

The observations showed a clear dose-response relationship in the emerged midges. An influence of the solvent used on the emergence of the midges could be excluded. At 1000 mg/kg sediment d.w., no female midges emerged.

Development Rate

An influence of the solvent used to apply the test item to the sediment on the development rate of the midges could be excluded for males, but not for females.

Validity criteria fulfilled:
yes
Remarks:
see overall remarks for details. The data provide evidence that the validity criteria were fulfilled.
Conclusions:
The sediment toxicity of AHTN was assessed in a 28d test with midge larvae of Chironomus riparius according to OECD TG 218. The organic carbon content in the sediment was 2.4 %. The NOEC of the emergence ratio is 500 mg AHTN/kg sediment dry weight (nominal). The NOEC for the developmental rate is more sensitive: nominal 125 mg/kg dw and 101 mg AHTN/kg dw for both males and females after correcting the NOEC for the measured concentration of AHTN.
Executive summary:

A toxicity test was carried out with the Chironomus riparius using sediment that was formulated from 5% Sphagnum moss peat, 75% quartz sand (>50% in range 50-200μm), 20% kaolinite clay and 0.05% calcium carbonate to adjust the pH between 6.5 and 7.0.

At the same time 0.2-0.25% Urtica powder was added as feed. The formulated sediment was conditioned for 7 days prior to application of the test material. The test material was solved in acetone to prepare the stock solutions for each concentration. The proper volumes were mixed first with dry quartz sand allowing the solvent to evaporate. Next the sand was mixed with the formulated sediment to achieve the intended nominal concentration levels. Each glass vessel contained a layer of 1.5 to 3 cm of sediment and the water (Elendt medium M4) volume was 3.5 to 4.5 times the sediment volume.

The test animals were introduced after an equilibration period of 1 week. The tests were carried out at 20 ºC under a 16/8 hours L/D cycle. The overlying water was slightly aerated during the test. No additional food was given during the test.

Test concentrations were measured. Samples of porewater and overlying water were extracted by SPE using Speedisks. Sediment samples were freeze-dried and analysed by GC/MS after solvent extraction. The results are reported by Belfroid and Balk (2005).

Midge larvae of the Chironomus riparius were exposed to nominal concentrations of 1000, 500, 250, 125, 62.5 mg AHTN/kg sediment dry weight (plus control and solvent control).

The test was carried out in a substrate containing 2.4% organic carbon.

The emergence ratio for males remained stable up to 500 mg/kg sediment dry weight, but at 1000 mg/kg sediment d.w., no female midges emerged. The NOEC for both males and females determined was the nominal concentration of 125 mg/kg dw, which is equivalent to measured 100 mg/kg dw when taking the results of the recovery experiments into account.

Description of key information

Long term toxicity studies were carried out with three species of sediment organisms i.e. the midge larvae Chironomus riparius, the Amphipoda Hyalella azteca and the aquatic oligochaete worm Lumbriculus variegatus. The studies were performed according to or in line with OECD TG 218 and under GLP (Rel. 1). The most sensitive species was Lumbriculus variegatus with NOEC 7.1 mg/kg dw (measured concentration).

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:
7.1 mg/kg sediment dw

Additional information

The tests with sediment organisms were carried out according or similar to OECD TG 218 and under GLP (Rel. 1). The three selected species represent a variety of taxonomic groups: insects, crustaceans and worms.

After preparation of the artificial sediment, food was added and the sediment was spiked with the appropriate amounts of AHTN. The test animals were introduced in the test system after an equilibration period of 1 week. No additional food was given to ensure oral exposure with spiked material. Samples of the sediment, overlying water and porewater were analysed to establish the actual exposure concentrations.

The lowest NOECs for Lumbriculus variegatus and Hyalella azteca were of the same order of magnitude: 7.1 and 18.2 mg/kg dw (measured). With a NOEC of 101 mg/kg dw, Chironomus riparius was considerably less sensitive.

In line with the protocol, the sediment contained circa 2% organic carbon. Note that for the derivation of the PNEC and for the estimation of the PEC, the organic carbon content is assumed to be 5%.The lowest NOEC of 7.1 mg/kg dw for L. variegatus, after correction for the content of organic carbon from 2.06 to 5 %, is equivalent to 17.2 mg/kg dw in a standard sediment containing 5% organic carbon.

Summary of the sediment toxicity tests with AHTN

Species

Guideline

Result (mg/kg ds, measured)

OC content

Reference

Remarks

 

 

 

 

 

 

Hyalella azteca

OECD 218

28d-NOECgrowth = 18.2 (meas.)

2.15 %

Egeler 2004

Rel. 1

Chironomus riparius

OECD 218

28d-NOECdev. = 101

2.4 %

Egeler 2004a

Rel. 1

Lumbriculus variegatus

OECD 218

28d-NOEC growth = 7.1

2.06%

Egeler 2004b

Rel. 1