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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:
Jun - Oct 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
The distribution of 14C, deriving from 14C-labelled LBQ657 (900-04) and/or its transformation products, within the water, pore water and sediment was determined in the limit concentration. Furthermore, the LBQ657 (900-04) concentration in the spike solution used to prepare the sediment, including the radiochemical purity of 14C-labelled LBQ657 (900-04) was determined.
Frequency: Days 0 and 28.
Vehicle:
yes
Remarks:
ethanol
Details on sediment and application:
The batch of LBQ657 (900-04) tested was a white powder. The purity of this batch is described in the Certificate of Analysis. The batch of [14C]LBQ657 was a solid with a radiochemical purity of 99% (as determined by the supplier), which was also verified at WIL Research Europe B.V.
Test concentrations were prepared by mixing spiked sand with sediment. For 1000 mg/kg d.w. a spike solution of 2.0 mg/ml in ethanol1, containing a mixture of 14C-labelled and non-labelled test substance was prepared. The ratio of 14C-labelled and non-labelled test substance was chosen so that the amount of radioactivity in the samples was sufficient to allow quantification of the radioactivity (approximately 0.1 MBq/vessel).
For 1000 mg/kg d.w. the amount of the spike solution
corresponded with approximately 60 mg/vessel. Per replicate (vessel) 30 g sand was spiked with 30 ml ethanol stock. After evaporation of the solvent the coated sand was mixed with sediment. Care was taken to ensure that LBQ657 (900-04) was thoroughly and evenly distributed within the sediment.
Test media were prepared bulk wise and subsequently distributed over replicates. The total amount of wet sediment was 85 g per test vessel, consisting of 30 g treated sand and 55 g OECD medium2. This corresponds theoretically with approximately 60 g dry sediment per vessel, based on the determined moisture (37%) the actual amount was 62 g dry sediment.
Preparation of the 1.0, 10 and 100 mg/kg d.w. test concentrations was comparable to the highest concentration, except that these concentrations were not performed with 14C-labelled LBQ657. Lower stock solutions were prepared by subsequent dilutions in ethanol.
Test organisms (species):
Chironomus riparius
Details on test organisms:
temperature of ca. 20°C. The fertilized egg masses hatch 2 to 3 days after placing in water.
Thereafter the larvae undergo four stages. L2 larvae emigrate to the sediment. After the fourth stage, the larvae change into pupae. Immediately after the pupa moves to the surface of the water the midge emerges from the pupal skin. The emergence of male midges starts earlier than that of the females.
Females are a little larger and darker than males. Males have plumose antennae. Mating occurs in swarming. After 1-2 days the female midge lays an egg mass, 2 to 3 days later a second, but smaller, egg mass can be produced. Midges have a life span of four to eight days.
Study type:
laboratory study
Test type:
static
Water media type:
freshwater
Type of sediment:
artificial sediment
Limit test:
yes
Duration:
28 d
Exposure phase:
total exposure duration
Remarks:
28 days (after introduction of the larvae)
Post exposure observation period:
Frequency: Days 0 and 28.
Hardness:
196 – 232 mg CaCO3/l
Test temperature:
20.0 ± 1.3°C
pH:
7.7 – 8.4
Dissolved oxygen:
7.0 – 8.9 mg/L
Reference substance (positive control):
no
Key result
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
> 280 mg/kg sediment dw
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
emergence rate
Key result
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
> 280 mg/kg sediment dw
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
development rate
Key result
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
>= 280 mg/kg sediment dw
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
emergence rate
Key result
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
>= 280 mg/kg sediment dw
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
development rate
Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study with Chironomus riparius, no statistical significant reduction of emergence and no statistical significant effect on development rate were observed at 280 mg/kg d.w. (NOEC).
The 28-day EC50 for emergence and development rate was higher than 280 mg/kg d.w..

Description of key information

Under the conditions of the present study with Chironomus riparius, no statistical significant reduction of emergence and no statistical significant effect on development rate were observed at 280 mg/kg d.w. (NOEC).

The 28-day EC50 for emergence and development rate was higher than 280 mg/kg d.w..

Key value for chemical safety assessment

EC50 or LC50 for freshwater sediment:
280 mg/kg sediment dw
EC10, LC10 or NOEC for freshwater sediment:
280 mg/kg sediment dw

Additional information