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Sediment toxicity

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Description of key information

28d-NOEC for Chironomus riparius = 250 mg/kg dwt (emergence rate, nominal; Egeler and Gilberg 2004)
28d-NOEC for Lumbriculus variegatus = 26.5 mg/kg dwt (reproduction, nominal; Egeler and Gilberg 2004)
28d-NOEC for Hyalella azteca = 14.5 mg/kg dwt (growth, nominal, Egeler 2004), NOEC = 7.1 mg/kg dwt expressed as measured concentration.
The organic carbon content in the tests was circa 2%. Standardised for 5% OC the lowest NOEC was 19.7 mg/kg dwt (based on measured concentration).

Key value for chemical safety assessment

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

Additional information

Toxicity tests were carried out with three species of sediment organisms, according to or in line with the OECD TG 218 (Draft December 2002): Sediment-water chironomid toxicity test using spiked sediment.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. 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 toof 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). These tests were carried out under GLP and they are completely documented. The results are summarised in the table:

 Sediment toxicity of HHCB (GLP and completely documented):

Test species

Guideline

Results1(mg/kg dwt) <95% c.l.>

Remarks2

Insectae

Chironomus riparius

 

OECD 218

NOEC >1000 (development rate)

NOEC = 250 (emergence ratio)

LOEC = 500  (emergence ratio)

EC50= 402 <260 – 829> (emergence ratio)

 

Key study, Rel. 1

Egeler & Gilberg 2004a

28 d

solvent: acetone, 2.6% OC

n=5

identification by GC/MS

start conc. 80% of nomi­nal

end conc. 82% of start

Crustaceae, Amphipoda

Hyalella azteca

 

OECD 218

NOEC = 34.7 (survival)

LC50= 62.5 <49.8 – 78.4>

NOEC = 14.5 (growth, nominal)

NOEC = 7.1 (growth, measured)

LOEC = 34.7 (growth)

EC50= 53.5 <53.0 – 54.0> (growth)

Key study, Rel. 1

Egeler 2004

28 d

solvent: acetone, 1.8% OC

n=5

identification by GC/MS

start conc. 54% of nomi­nal

end conc. 96% of start

Oligochaeta

Lumbriculus variegatus

 

OECD 218

NOEC = 140 (survival)

NOEC = 26.5 (reproduction)

LOEC = 60.9 (reproduction)

EC50= 74.1 <42.5 – 165.7> (reproduction)

NOEC = 60.9 (biomass)

LOEC = 140 (biomass)

Key study, Rel. 1

Egeler & Gilberg 2004b 48h 28 d

solvent: acetone, 2.1% OC

n=5

identification GC/MS

start conc. 60% of nomi­nal

end conc. 85% of start

1   nominal concentrations; <95% confidence limits>

2   The number of concentrations tested (n) excludes control and solvent control

Chironomus

A toxicity test was carried out with Chironomus riparius, according to OECD TG 218 (Draft December 2002): Sediment-water chironomid toxicity test using spiked sediment (Egeler and Gilberg 2004).The test was carried out with five concentrations ranging from 62.5 to 1000 mg/kg dwt with step size 2. Twenty animals, first instar larvae, were used in each of the four replicates per test concentration, in the control and in the solvent control. The test concentrations were measured on day 0, 14, 20 and 28 in the control, 125 and 1000 mg/kg. After the equilibrium period the test concentration was on average 80% of the intended nominal test concentration. At termination of the test, the average concentration was 82% of the concentration at the start. The development rate was not affected up to 1000 mg/kg for both males and females. The emergence ratio was the more sensitive endpoint. A clear dose response relation was found for the emergence of the midges. The data for males and females were pooled for the statistical analysis.The NOECemerg. was 250 mg/kg (-4%), the EC15 was 259 mg/kg with 95% confidence limits <164 – 435> and the EC50 was 402 <260 – 829> mg/kg dwt.The actual concentrations remained largely within 80% of the initial concentrations at day 0. The NOEC in this study was 80% of 250 mg/kg or 200 mg/kg dwt (measured concentration).

Hyalella

A toxicity test was carried out with the Amphipoda Hyalella azteca, in line with the OECD TG 218 (Draft December 2002): (Egeler 2004).Hyalella Azteca was tested in five concentrations ranging from 6 to 200 mg/kg sediment with step size 2.4.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, 35 and 200 mg/kg. At the start of the test the test concentration was on average 54% of the intended nominal test concentration. At termination of the test, the average concentration was 96% of the concentration at the start. Survival was not affected up to 35 mg/kg, whereas the mortality in 83 mg/kg was 88% and 100% in 200 mg/kg. Thus the LC50 was 62.5 mg/kg. Growth was inhibited at 35 mg/kg (LOEC). The length of the amphipods was 9% below the pooled control at 35 mg/kg, whereas the inhibition for the (total) biomass per replicate was 15%. At the NOEC, 14.5 mg/kg, the inhibition was 3% for length and none for biomass. The EC50 for biomass was 53.5 mg/kg. The actual concentrations at day 0 were on average 49% of the initial concentrations and remained at this level during the test. The actual concentration on day 0 at the LOEC level was measured: 16.3 mg/kg.The actual concentration at the level of the NOEC (nominal 14.5 mg/kg) was 7.1 mg/kg in this study

Lumbriculus

A toxicity tests was carried out with the aquatic oligochaete worm Lumbriculus variegatus, in line with the OECD TG 218 (Draft December 2002): Sediment-water chironomid toxicity test using spiked sediment (Egeler and Gilberg 2004). Lumbriculus variegatus was tested in concentrations ranging from 5 to 140 mg/kg with step size 2.3 .The test animals were 'synchronised' before the start of the test to avoid high variation in the test results. Four replicates each with 10 regenerated 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, 20 and 28 in the control, 26.5 and 140 mg/kg. At the start of the test the test concentration was on average 60% of the intended nominal test concentration. At termination of the test, the average concentration was 85% of the concentration at the start. Survival was not affected up to the highest test concentration. The total number of worms (including adult and regenerated worms) at the end of the test was evaluated as a parameter of reproduction. As compared to the solvent control, reproduction was significantly inhibited by 50% in 61 mg/kg, whereas the inhibition was 8% at 26.5 mg/kg (NOECrepr.).The EC50(repr.)was 74.1 <42.5 – 165.7> mg/kg, the EC15(repr.)was 24.1 <1.8 – 42.1> mg/kg.Growth as measured by biomass was significantly inhibited by 80% at 140 mg/kg, whereas at 61 mg/kg the inhibition was 13% (NOECbiomass). The EC50(biomass) was 97.7 <77.7 – 119.7> mg/kg, the EC15(biomass) was 62.4 <37.7 – 78.3> mg/kg. The NOEC in this study was 26.5 mg/kg. The actual concentration on day 0 at the level of the NOEC was measured: 16.2 mg/kg sediment. The NOEC in this study is taken to be 16.2 mg/kg (measured concentration).

These studies are KEY studies for the derivation of PNECsedment.