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Sediment toxicity

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Reference
Endpoint:
sediment toxicity: short-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16 - 26 Jan 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP- guideline study
Qualifier:
according to
Guideline:
other: OSPARCOM guidelines (2005) A sediment Bioassay using an amphipod corophium sp
GLP compliance:
yes
Remarks:
GLP administered by the UK Dept of Health as stated by the study director.
Analytical monitoring:
no
Vehicle:
yes
Details on sediment and application:
PREPARATION OF SPIKED SEDIMENT
- Mixing of different substrates: test material was mixied with a small quantity of dry sediment and a solvent of low toxicity. Dry sediment was then incorporated with the wet sediment. The mixing vessels were then placed on a platform shaker at 150 rpm for 3 hours. After this period, the contents of each container were equally distributed between the replicate vessels, three for test concentrations and five for control vessels.
- Chemical name of vehicle: a solvent of low toxicity such as acetone, ethanol or triethylene glycol if necessary (not further specified in study)
- Source of sediment: sediment was collected from a site in the Bay of Suckquoy, Toab in Orkney
Details on test organisms:
TEST ORGANISM
- Common name: mud shrimp
- Source: test organisms and sediment were collected from a site in the Bay of Suckquoy, Toab in Orkney
- Details on collection: specimens were gently sieved from their native sediment and held in plastic containers (5 L) containing some ambient water, with a small amount of detritus, until transfer to the laboratory. On return to the laboratory, the Corophium were transferred in ambient water to polythene tanks (200 L) capacity, gentle aeration was supplied.
- Holding period in the laboratory: between 3 and 14 d
- Holding temperature: 15 ± 2 °C

ACCLIMATION
- Acclimation period: 4 d
- Acclimation conditions: the stock animals were gradually acclimated from the ambient salinity of less than 5‰ to that of undiluted seawater (approximately 35‰) in increments of approximately 10‰ per day. Once acclimation is complete, the stock tanks were maintained under semi-static conditions until the initiation of the test. Dead or impaired animals are removed when observed.
- Type and amount of food: sufficient detrital material is retained in each tank to provide food and some bottom cover
Study type:
laboratory study
Test type:
not specified
Water media type:
saltwater
Type of sediment:
natural sediment
Limit test:
no
Duration:
10 d
Exposure phase:
total exposure duration
Test temperature:
13.4 - 14.9°C
pH:
7.98 - 8.34
Dissolved oxygen:
92 - 98%
Salinity:
31 - 38‰
Nominal and measured concentrations:
Nominal target wet weight concentrations: control, 10, 100, 320, 1000 and 10000 mg/kg
Nominal dry weight concentrations: control, 14.68, 146.44, 468.14, 1442.30 and 13864.37 mg/kg
Details on test conditions:
TEST SYSTEM
- Test container (material, size): 1 L glass beakers. Each row of beakers was covered with a rectangular sheet of perspex perforated with a small hole above the centre of each beaker.
- Sediment volume: approx. 150 mL
- Weight of wet sediment: 750.56, 751.56, 750.34, 751.06, 749.62 g (corresponding to the 10, 100, 320, 1000, 10000 mg/kg respectively)
- Overlying water volume: 850 mL
- Aeration: yes
- Aeration frequency and intensity: a stream of air bubbles were released at a depth of approximately 6 cm

EXPOSURE REGIME
- No. of organisms per container (treatment): 20
- No. of replicates per treatment group: 3
- No. of replicates per control: 5

OVERLYING WATER CHARACTERISTCS
- Type of water: 1 µm filtered UV treated seawater (supplied by pump from Scapa Flow, Orkney)

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Bay of Suckquoy, Toab in Orkney

HANDLING OF NATURAL SEDIMENT
- Treatment after sampling and storage: sediment was wet-sieved through 0.6 mm mesh to remove larger infaunal organisms and Corophium within the test size range, and allowed to settle in tall polyethylene containers. After settling, supernatant water was decanted and sediment was stored in a room at approx. 4 ± 2 °C, until required for testing
- Sediment treatment prior to test beginning: sediment was thoroughly homogenised and a representative sample was taken for wet and dry weight determination

CHARACTERIZATION OF SEDIMENT
- Particle size distribution: well sorted sediment (fine sand with silt/clay), 151 µm median particle diameter
- silt/clay content: 3.56%
- Total organic material content (%): 1.34%

OTHER TEST CONDITIONS
- Photoperiod: constant dim illumination

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : at the end of the test period, the contents of each beaker were gently sieved through a 0.6 mm mesh, and all surviving animals separated and counted. Missing animals were counted as dead
Reference substance (positive control):
no
Duration:
10 d
Dose descriptor:
LC50
Effect conc.:
901.92 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% CI: 808.96 - 971.84 mg/kg
Reported statistics and error estimates:
Effect values were calculated using ToxCalc Version 5 Tidepool Scientific Software.
The ratio of wet weight to dry weight in sediment was used to convert nominal exposure concentrations on a wet weight basis to nominal exposure concentrations on a dry weight basis (1.47).

LC90 (10 d): 1334.22 mg/kg sediment (dw)

NOEC (10 d): 146.44 mg/kg sediment (dw)

Control mortality: 2% (guideline criterion: =< 15%)

Table 1: Observed mortalities of the testet organism in the test item and in the controls after 10 d

Treatment (mg/kg dry weight) Mortality (proportion dead) Raw mean
Control 0.05 0 0 0.05 0 0.02
14.68 0 0.05 0.05 - - 0.03
146.44 0 0.05 0.05 - - 0.03
468.14 0.2 0.1 0.05 - - 0.12
1442.3 1 1 1 - - 1
13864.37 1 1 1 - - 1

Description of key information

LC50 (10 d) = 901.92 mg/kg dw sediment for Corophium volutator (OSPAR community guideline)

Key value for chemical safety assessment

Additional information

One study is available with D-Glucopyranose, oligomeric, undecyl glycoside (CAS 98283-67-1) in which the toxicity to the saltwater sediment organism Corophium volutator was tested (Hudson, 2009). The laboratory test was conducted according to GLP and OSPAR community guideline (2005). The mud shrimp in natural sediment were exposed to concentrations of 14.68, 146.44, 468.14, 1442.30 and 13864.37 mg/kg (nominal, dry weight sediment) for 10 d in a laboratory study. A solvent of low toxicity was used as a vehicle. A LC50 (10 d) of 901.92 mg/kg dw sediment based on mortality was determined.