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Sediment toxicity

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Administrative data

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: According to international guideline(s), GLP-compliant, performed in recognized contract research organization, no restrictions, fully adequate for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)
Deviations:
yes
Remarks:
(at one inspection day, water temperatures measured differed for 2 °C in some of the test vessels. However, this is considered not to have affected the outcome or the validity of the test as no adverse effects were observed throughout the test.)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
425-220-8
EC Name:
-
Cas Number:
5945-33-5
Molecular formula:
C39H34O8P2
IUPAC Name:
(1-methylethylidene)di-4,1-phenylenetetraphenyl diphosphate

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
SEDIMENT
- Concentrations: solvent control, 1000 mg/kg
- Sampling interval: Days -7, 0 and 28
- Sample storage before analysis: -20 °C (if necessary)

PORE WATER
- Concentrations: solvent control, 1000 mg/kg
- Sampling interval: Days 0 and 28
- Sample storage before analysis: -20 °C (if necessary)

OVERLYING WATER
- Concentrations: solvent control, 1000 mg/kg
- Sampling interval: Days 0 and 28
- Sample storage before analysis: -20 °C (if necessary)

Test substrate

Vehicle:
yes
Details on sediment and application:
PREPARATION OF SPIKED SEDIMENT
Aliquots of solvent stock solutions were added to small sediment portions. After evaporation of the solvent, premixes were incorporated into the formulated sediment with an aliquot of water and mixed using a Hobart mixer. The sediment was then dispensed to glass beakers and covered with Elendt M4 medium using a plastic disk to prevent disturbance of the sediment.
- Equilibration time: 7 days (aerated)
- Controls: Controls were prepared in a similar manner; solvent control sediment received acetone only whilst the control sediment remained untreated
- Chemical name of vehicle: acetone
- Evaporation of vehicle before use: yes

Test organisms

Test organisms (species):
Chironomus riparius
Details on test organisms:
TEST ORGANISM
- Handling of egg masses and larvae: Chironomus riparius were obtained from an in-house Iaboratory culture
Larvae were maintained in glass beakers with a 5-10 mm layer of fine quartz sand covered by reconstituted water (Elendt M4) in a temperature controlled room at 21°C to 24°C. The lighting cycle was controlled to give a 16 hour light and 8 hour darkness cycle with 20 minute dawn and dusk transition periods. The cultures were gently aerated, so as not to disturb the substrate, through narrow bore glass tubes. The culture vessels were housed in a sealed clear perspex cabinet (breeding box) with cotton sleeves to enable access.
Any gelatinous egg masses produced by breeding adult midges were removed from the culture vessels and transferred to separate vessels and, if required, larvae from this used to populate new cultures
- Age of animals at beginning of exposure: first instar larvae (2-3 days old)
- Feeding during breeding
- Food type: Tetramin flake food suspended in water
- Amount: approx. 250 mg per vessel, added to the overlying water
- Frequency: daily
Breeding conditions were the same as in the test.

Study design

Study type:
laboratory study
Test type:
static
Water media type:
freshwater
Type of sediment:
artificial sediment
Limit test:
yes
Exposure duration
Duration:
28 d
Exposure phase:
total exposure duration

Test conditions

Hardness:
242 - 322 mg/L as CaC03
Test temperature:
21±1 °C water temperature. Water temperatures of 23 °C were measured on Day 15 in some of the test vessels. This was considered not to have affected the outcome or the validity of the test as no effect on emergence was observed throughout the test.
pH:
7.8 - 8.7; no treatment related differences observed
Dissolved oxygen:
5.8 - 8.9 mg O2/L (65 - 100% air saturation); no treatment related differences observed
Ammonia:
solvent control: 0.019 and 0.92 mg/L as NH3 (Day 0 and 28)
test group: 0.021 and 0.20 mg/L as NH3 (Day 0 and 28)
Nominal and measured concentrations:
nominal: 1000 mg/kg dry weight sediment
measured:
Day -7: 92% of nominal in sediment before placement of overlaying water
Day 0: 93% of nominal in sediment; 0.0038 mg/L in overlying water, 1.99 mg/L in interstitial water
Day 28: 74% of nominal in sediment; 0.0029 mg/L in overlying water, 1.02 mg/L in interstitial water.
Details on test conditions:
TEST SYSTEM
- Test container: 600 mL glass beakers, diameter approx. 8 cm
- Depth of sediment and overlying water: sediment: 2 cm; overlying water: 8 cm
- Aeration: yes
- Aeration frequency and intensity: continuous, approximately 1 bubble/second via narrow bore glass tubes approximately 2 - 3 cm above the sediment layer
EXPOSURE REGIME
- No. of organisms per container (treatment): 20
- No. of replicates: 6 replicates were prepared for each of the control, solvent control and 1000 mg/kg test concentration, plus an additional two replicates of each for sacrificing on Day 10 of the exposure period.
- Feeding regime: added to the overlying water
- Type and preparation of food: suspensions of Tetramin flake food
- Amount of food: 0.25-0.5 mg per larvae and day; increased to 0.5-1 mg per larvae and day after the first ten days
OVERLYING WATER CHARACTERISTCS
- Type of water: Elendt M4 medium (final concentrations differed from those indicated in OECD 218. However, this did not affect the outcome or the validity of the test)
CHARACTERIZATION OF ARTIFICIAL SEDIMENT
- Composition (artificial substrate):
Industrial quartz sand: 76 % w/w
Kaolinite clay: 20% w/w% w/w
Sphagnum moss peat: 4% w/w
- Method of preparation (if artificial substrate): not specified
- Maturation of artificial substrate (if any): not specified
- Moisture: approx. 40% of dry weight
- pH whole sediment: 7.0 ± 0.5
- Total organic carbon (%): 2.2
OTHER TEST CONDITIONS
- Photoperiod: 16 h light, 8 h dark with a 20 minute dawn and dusk transition period
- Light intensity: 817 – 882 lux
EFFECT PARAMETERS MEASURED (with observation intervals if applicable): number and sex of live, emerged adult midges was recorded daily. On Day 10 of the exposure period, larval survival and weight was measured
VEHICLE CONTROL PERFORMED: yes
TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 1.0, 10, 100 and 1000 mg/kg (dry weight of sediment)
- Results used to determine the conditions for the definitive study: no significant reduction in emergence of adult midges observed at any test concentration employed in the 28-day range-finding test
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
28 d
Dose descriptor:
NOEC
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:
EC50
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:
EC50
Effect conc.:
>= 1 000 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
development rate
Details on results:
No significant differences were observed between the solvent control and control and 1000 mg/kg test groups
- in Day 10 larval survival and growth (mean larval dry weight);
- between the numbers of males and females.
The cumulative number of visible pupae that failed to emerge was <3% for the solvent control and control and 1000 mg/kg test groups, respectively.
There were no sub-lethal effects observed.
Reported statistics and error estimates:
Statistical analysis of the emergence data was performed using a Students t-test. All statistical analyses were performed using the SAS computer software package (SAS 1999 - 2001). Analysis was performed on the emergence ratio (ER) values transformed by the square root arcsin function prior to statistical analysis in order to obtain an approximate normal distribution and to equalise the variance.

Any other information on results incl. tables

Table 1: Cumulative Daily Emergence of Male and Female Chironomids and Percent Emergence of Test Animals at End of Exposure Period (Day 28)

 

BDP (mg/kg)

Number of Female and Male Chironomids Emerged

Total

% Cumulative

Emergence

Day

15

16

17

18

19

20

21

22

23

24

25

26

27

28

Control

-

-

2M

-

15M

-

19M

-

13M

1F

8M

1F

2M

8F

1M

12F

-

8F

-

10F

1M

2F

-

2F

-

3F

-

-

61M

47F

90

Solvent Control

-

-

3M

-

9M

-

16M

-

12M

-

10M

4F

5M

6F

-

9F

-

12F

-

6F

-

6F

-

5F

-

3F

-

-

55M

51F

88

1000

2M

-

2M

-

6M

-

10M

-

22M

1F

7M

2F

9M

2F

3M

1F

1M

10F

-

12F

1M

12F

1M

2F

-

2F

-

2F

64M

46F

92

M = Male

F = Female

- = No emergence

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Emergence started between Day 15 and 16 and was >70% at test end, O2 concentration >60%, pH 6-9, water temperature 21±1°C (except 23°C in some vessels on one occasion. However this did not affect the validity of the test since no effects were observed).