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Sediment toxicity

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sediment toxicity: short-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 April 2011 to 9 May 2011
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The test was conducted according to the principles of GLP and to recognised OSPARCOM guideline.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
other: OSPARCOM guidelines (2006) Part A. A sediment bioassay using an amphipod Corophium sp
On day 3 Dissolved Oxygen levels for 2 beakers fell below guideline criteria by 2% and 5% respectively. This deviation is thought to not to have had an effect on the result as mortalities were consistent with other replicates
GLP compliance:

Test material

Constituent 1
Test material form:
other: Solid

Sampling and analysis

Analytical monitoring:

Test substrate

Details on sediment and application:
Sediment was collected on 14th April 2011 from a site in the Bay of Suckquoy, Toab in Orkney from a point adjacent to the site of Corophium collection and received on site on 15th April 2011. On return to the laboratory, the 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, the supernatant water was decanted and the sediment stored at approximately 4±2 °C, until required for testing.

Particle size analysis characterised the sediment as well-sorted, fine sand with a silt/clay content of 31.6% by weight. Median particle diameter was 100 μm. The organic material content was estimated from weight loss on ignition to be 2%.

Immediately before the initiation of the test, the sediment was thoroughly homogenised and a representative sample taken for wet and dry weight determination. The ratio of wet weight to dry weight was subsequently used to convert nominal exposure concentrations on a wet weight basis to nominal exposure concentrations on a dry weight basis.

Test material preparation
In order to determine an appropriate test preparation method, an assessment was made of its behaviour in seawater. A 1000 mg.l-1 stock was prepared in filtered seawater, and the resulting mixture was stirred for one hour. If the material was observed to be soluble then its behaviour was assessed. If it was poorly soluble after one hour then it was stirred for approximately a further 19 hrs and then left to settle for one hour and its behaviour assessed.
The test material was poorly soluble in seawater and was prepared by mixing initially with a small quantity of dry sediment. The dried sediment and mixed test material was then incorporated with the wet sediment within the mixing container.
The mixing vessels were then placed on a platform shaker at approximately150 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.

Test organisms

Test organisms (species):
Corophium volutator
Details on test organisms:
The test population of Corophium volutator was collectedon 14 April 2011 from an uncontaminated site in Orkney. The site location at Bay of Suckquoy, Toab, Orkney was chosen because of its high natural densities of Corophium and, in accordance with the guidance document ‘Biological Effects of Contaminants; Corophium sp. sediment bioassay and toxicity test’, BD Roddie & JE Thain, published by ICES in 2001.
Initial parameters of the holding water were recorded upon arrival at the Opus laboratory. Specimens were gently sieved from their native sediment and held in plastic containers (approximately 5l capacity) 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 of approximately 200 litre capacity, gentle aeration was supplied. The tanks were held at approximately 15±2 °C.

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. The holding period in the laboratory is between 3 and 14 days. Sufficient detrital material is retained in each tank to provide food and some bottom cover, but not of a density that prevents daily observation of mortality and morbidity. Dead or impaired animals are removed when observed.

Specimens of approximately 5 mm in body length (excluding rostrum) were used in the toxicity tests.

Study design

Study type:
laboratory study
Test type:
Water media type:
Type of sediment:
natural sediment
Limit test:
Exposure duration
10 d
Exposure phase:
total exposure duration

Test conditions

Test temperature:
The temperature was measured on Day0, 3, 7 and 10.
Temperature ranged from 15.2-15.9°C
The pH was measured on Day0, 3, 7 and 10.
pH ranged from 7.87-8.18
Dissolved oxygen:
The dissolved oxygen was measured on Day0, 3, 7 and 10.
The dissolved oxygen ranged from 80-99%.
The salinity was measured on Day0, 3, 5, 7 and 10.
The salinity ranged from36-43ppt (Maintained at ±4 ppt from the initial 0h figure during the test)
Nominal and measured concentrations:
Nominal test concentrations:
13.93, 138.87, 442.22, 1344.54 and 13093.74 mg/kg dry weight
Details on test conditions:
Tests were conducted in 1 litre capacity glass beakers each containing 2 cm depth (approximately 150 ml) of amended sediment and 850 ml of overlying seawater (1 μm filtered ultra violet treated seawater). Test beakers were maintained in a controlled temperature room for a test period of 10 days.

Three replicates were prepared for each test concentration; controls are replicated five times. The beakers were assigned positions within the test area, arranged in rows of three to five and spaced to maintain effective separation of different treatments. Each row was covered with a rectangular sheet of perspex perforated with a small hole above the centre of each beaker. Aeration was provided and a stream of air bubbles was released at a depth of approximately 6 cm.

Twenty animals were added to receiving vessels in two groups of ten and then dispensed into a test vessel. Sixty organisms were exposed in total per concentration and one hundred in five vessels for controls. The final level of water in each test vessel was marked with a permanent marker.

Any visible signs of animals on the sediment surface whether alive or dead were recorded.

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; early mortalities will either have been consumed by survivors or have decomposed during the test period.

Results and discussion

Effect concentrationsopen allclose all
10 d
Dose descriptor:
Effect conc.:
6 116.15 mg/kg sediment dw
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
Remarks on result:
other: 95% confidence range was 5502.47 - 6691.14 mg/kg (dry weight) sediment
10 d
Dose descriptor:
Effect conc.:
138.87 mg/kg sediment dw
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
Results with reference substance (positive control):
No positive control

Any other information on results incl. tables

Result tables see attached background material

Applicant's summary and conclusion

Validity criteria fulfilled:
Temperature, pH & salinity were within recommended ranges.Dissolved Oxygen in 2 beakers on day 3 was below guideline criteria by 2% & 5%..This deviation is considered to have had no effect on the result as mortalities were consistent with other replicates
The 10 day LC50 value for the test substance was found to be 6116.15 (via dried sediment) to the marine amphipod Corophium volutator in the sediment phase.
Executive summary:

The test substance exhibited a 10 day LC50 value of 6116.15 mg/kg, (95% confidence range was 5502.47 - 6691.14 mg/kg) dry weight of sediment to the marine amphipod Corophium volutator. The NOEC value was 138.87 mg/kg dry weight of sediment.

The result is based on nominal concentrations and was calculated by Linear Interpolation within the Toxcalc suite of statistical analysis.

There were no interferences in this test.