Reaction mass of decamethyltetrasiloxane; dodecamethylpentasiloxane; hexamethyldisiloxane; octamethyltrisiloxane

Sediment toxicity

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2015-11-13 to 2016-12-15

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 225 (Sediment-Water Lumbriculus Toxicity Test Using Spiked Sediment)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

SEDIMENT
- Sampling interval: day 0, 3, 7 , 14,. 28

PORE WATER
- Sampling interval: day 0, 3, 7 , 14,. 28

OVERLYING WATER
- Sampling interval: day 0, 3, 7 , 14,. 28

Vehicle:

yes

Remarks:

acetone

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Details of spiking: At day -3, 1.5 kg (equivalent to 1.15 L) wet weight of sediment was weighed in individual 3.5 L glass jars, followed by 0.77 L of fortified well water to give an approximate water volume to sediment to headspace volume ratio of 2:3:4. The jar contents were shaken manually to suspend the sediment immediately prior to dosing. Each jar was manually shaken to suspend the sediment and then dosed with 0.85 mL of the appropriate dosing stock solution. The test substance was applied under the surface of the water using a gas tight syringe. Following dosing, the jars were immediately sealed and manually shaken again to re-suspend the sediment, and thus distribute the test substance. After settling overnight, the overlying water was decanted and 1.66g of both Urtica powder and alpha cellulose (0.25% of the total sediment dry weight each) were weighed out and manually mixed into the sediment for each concentration as a supplemental food source for the test organisms. The addition of the food following dosing was to ensure it was adequately mixed into the sediment and equally incorporated for each control and treatment level. Adding the food prior to dosing could result in food being suspended in the overlying water and never reincorporated into the sediment. The final sediment dry weight following this addition was 0.6653 kg per concentration. The sediment was then allocated to the replicate test vessels.
- Controls: solvent, negative
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (stock solution and final test solution):
- Stock solution: 10 mg/mL
- Dosing stock solutions 23.5, 11.8, 5.85, 3.00, 1.5 mg/mL
- Evaporation of vehicle before use:

Test organisms (species):

Lumbriculus variegatus

Details on test organisms:

TEST ORGANISM
- Common name: Lumbriculus variegatus
- Source: laboratory cultures maintained at Smither Viscient


ACCLIMATION
- Acclimation period: 12-14 days following synchronisation
- Acclimation conditions (same as test or not): organisms were placed in an aquarium with test sediment and laboratory well water under flow-through conditions. Renewal of overlying water in holding aquarium with the fortified well water used in the test at a rate of approximately half a volume replacement per day.
- Type and amount of food: 15 mL of finely ground suspension of flaked fish food (100 mg/mL)
- Feeding frequency: weekly
- Health during acclimation (any mortality observed): none

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

180 mg/L as CaCO3

Test temperature:

18 to 22°C

pH:

overlying water: 6.2 to 8.0 with the exception of one sample (day 21 of the control) which had a pH of 5.9. While this one measurement was outside of the acceptability criteria of pH 6 to 9, the biological performance in the negative control indicates that pH did not adversely affect the test organism.

Dissolved oxygen:

Dissolved oxygen was maintained above 30% air saturation meeting protocol and guideline criteria

Conductivity:

810 µS/cm

Nominal and measured concentrations:

nominal: 1.9, 3.8, 7.5, 15 and 30 mg/kg

measured: concentrations on day 0: 0.38, 0.80, 2.1, 2.6, and 2.7 mg/kg

measured: concentrations on day 3: 0.33, 0.55, 1.6, 1.9, and 1.4 mg/kg

measured concentrations on day 14: 0.24, 0.48, 1.2, 1.7 and 1.4 mg/kg

measured concentrations on day 28: 0.16, 0.22, 0.59, 0.86, and 0.88 mg/kg

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 600 mL clear glass beakers
- Sediment volume: 75 mL
- Sediment wet weight: 116g (average)
- Overlying water volume: 300 mL
- Depth of sediment and overlying water: sediment 1.5 cm, water 6 cm (ratio 1:4)
- Aeration: yes
- Aeration frequency and intensity: 1 to 3 bubbles per second
- Replacement of evaporated test water, if any:

EXPOSURE REGIME
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control / vehicle control: total of 6 control
- Feeding regime: added at start of test
- Type and preparation of food: Urtica powder and alpha cellulose added to sediment during sediment preparation

OVERLYING WATER CHARACTERISTCS
- Type of water (e.g. deionized, ground water, sea water, Elendt medium acc. to OECD 219): fortified well water
- Alkalinity: 180 mg/L as CaCO3
- Conductivity: 810 µS/cm

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Glen Charlie Pond, Wareham, Massachusetts. (SV Batch no. 072015)

HANDLING OF NATURAL SEDIMENT
- Storage conditions: under refrigerated conditions at approximately 4ºC

CHARACTERIZATION OF SEDIMENT
- Particle size distribution
- % sand: 91%
- % silt: 6%
- % clay: 3%
- %solids: 44.13%
- Sediment sieved: yes, wet pressed through a 2.0 mm sieve prior to use and characterisation
- pH dry matter and/or whole sediment: 5.3
- Ammonia content of pore water: 6.7 mg/L as N
- Total organic carbon (%): 3.0%
- Proof of absence of chemical contaminants: representative sample analysed for presence of pesticides, PCBs and toxic metals. None detected at concentrations considered to have an adverse impact on the test.

OTHER TEST CONDITIONS
- Light quality: fluorescent bulbs
- Photoperiod: 16 hours light, 8 hours darkness
- Light intensity: 350 to 490 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS
- Spacing factor for test concentrations: nominal L2 concentrations chosen for the definitive study were 1.9, 3.8, 7.5, 15, and 30 mg/kg based on sediment dry weight

PRELIMINARY TESTING/EXPOSURE
- range-finding concentrations: nominal concentrations of 0.025, 0.17, 1.1, 7.5 and 50 mg/kg
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 3
- control / vehicle control: negative and solvent control sediments were maintained
- results: Statistical analysis determined no significant reduction in the mean number of surviving oligochaetes or in the biomass among oligochaetes exposed to any treatment level compared to the solvent control.

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 2.7 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Remarks on result:

other: ≥4.5 mg/kg dry weight normalised to 5% organic carbon

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 2.7 mg/kg sediment dw

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Remarks on result:

other:

Remarks:

Since no concentration tested resulted in ≥ 50% reduction in the number of oligochaetes recovered, the 28-day EC50 value for oligochaete reproduction was empirically estimated to be > 2.7 mg/kg-dw, the highest initial measured sediment concentration tested.

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 2.7 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Details on results:

- mean number of oligochaetes recovered in the control and solvent control was 26 and 29, respectively
- mean biomass per replicate in the control and solvent control was 31 and 29 mg, respectively
- control and solvent control data met the minimum performance criteria of the guideline (i.e., population increase of ≥ 1.8)

At exposure termination (day 28), the mean number of surviving oligochaetes observed among the oligochaetes exposed to the 0.38, 0.80, 2.1, 2.6, and 2.7 mg/kg treatment levels was 30, 31, 31, 26, and 30, respectively. Due to a statistically significant difference between the control and solvent control reproduction, results of treatment levels were compared to the solvent control. Statistical analysis (Bonferroni’s Adjusted t-Test) determined no significant reduction in the mean number of surviving oligochaetes in any of the treatment levels tested compared to the solvent control (29 oligochaetes).

Mean biomass per replicate in the 0.38, 0.80, 2.1, 2.6, and 2.7 mg/kg treatment levels was 29, 29, 37, 29, and 28 mg, respectively. Statistical analysis (Bonferroni’s Adjusted t-Test) determined no significant difference in mean biomass in any of the treatment levels tested compared to the pooled control (30 mg).

Because measured sediment concentrations were well below 80% of nominal on test day 0 and continued to decline throughout the exposure, the initial measured concentrations (day 0) were utilised to express the biological endpoints for the exposure, as recommended in OECD guideline 225, and defined the treatment levels tested as 0.38, 0.80, 2.1, 2.6, and 2.7 mg/kg.

Table: Concentrations of L2 measured in sediment samples during the study exposing oligochaetes (Lumbriculus variegatus) to L2 applied to sediment.

Nominal Sediment Concentration (mg/kg)		Measured Sediment Concentration(mg/kg)			Mean Measured (mg/kg)	Percent of Nominal (%)
	Day 0	Day 3	Day 14	Day 28
Negative Control	< 0.074	< 0.072	< 0.0051	< 0.020	NA	NA
Solvent Control	< 0.074	< 0.072	< 0.051	< 0.020	NA	NA
1.9	0.38	0.33	0.24	0.16	0.28	15
3.8	0.80	0.55	0.48	0.22	0.51	14
7.5	2.1	1.6	1.2	0.59	1.4	18
15	2.6	1.9	1.7	0.86	1.8	12
30	2.7	1.4	1.4	0.88	1.6	5.3

Validity criteria fulfilled:

yes

Conclusions:

No effects on survival or biomass have been reported when testing the registered substance at a loading rate of 2.7 mg/kg dwt sediment with Lumbriculus variegatus. Therefore 28-day NOEC and LC50 values of ≥2.7 and >2.7 mg/kg have been determined respectively in a sediment containing 3.0% organic carbon.

Reference 2

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2009-04-29 to 2009-05-27

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to an appropriate OECD test guideline and in compliance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

SEDIMENT

- Sampling interval: Sediment samples were collected from the analytical replicates from each test concentration and control shortly after the introduction of the organisms on Day 0, on Day 7 and at test termination on Day 28.

Vehicle:

no

Details on sediment and application:

SEDIMENT

- Formulated sediment: The sediment used in the study was a formulated sediment based on the recommendations of OECD Guideline 218. The sediment was composed of approximately 10% sphagnum peat moss, 20% silt and clay (kaolin clay) and 70% industrial quartz sand. The sand and clay were mixed in a PK Twinshell mixer for 20 minutes without the peat, since the peat was added later. The targeted organic carbon content of the final mixture was 5.0 ± 1.0%. The dry soil was stored under ambient conditions until used. The final pH of the sediment was 7.0. The percent organic carbon of the sediment was found to be 2.2.

Test organisms (species):

Chironomus riparius

Details on test organisms:

TEST ORGANISM

- Source: Egg masses were obtained from Environmental Consulting and Testing, Superior, Wisconsin. The organisms were held for five days prior to the start of the test at approximately the same temperature and in water from the same source as the water used during the test. At test initiation, the midges were collected from the culture and impartially added one and two at a time to test chambers. All transfers were made below the air/water interface using wide-bore pipettes.

Study type:

laboratory study

Test type:

semi-static

Water media type:

freshwater

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

136-144 mg/L as CaCO3

Test temperature:

20 ± 2 ºC

pH:

pH ranged from 8.1 to 8.6

Dissolved oxygen:

≥7.1 mg/L (79% of saturation)

Salinity:

not applicable

Ammonia:

<0.17 to 6.28 mg/L (Ammonia levels exceeded 4.0 mg/L in the overlying water of some replicates on Days 7 and 14; therefore, the overlying water was partially renewed on those days in each replicate to prevent toxicity caused by high levels of ammonia).

Nominal and measured concentrations:

Nominal concentrations in mg/Kg: 0 (Control), 31, 63, 125, 250, 500 and 1000

Arithmetic mean measured concentrations in mg/Kg in the treated sediments: 7.4, 14, 39, 84, 210 and 435

The mean measured concentrations in the treated sediments are equivalent to 24, 23, 32, 34, 42 and 44% of nominal.

The results are interpreted with reference to the mean measured concentrations.

Details on test conditions:

TEST SYSTEM

- Test container (material, size): Test chambers were 2000-mL glass beakers containing approximately 2 cm of sediment and 8 cm of overlying water

- Aeration: yes

- Overlying water renewal: Overlying water was partially renewed on Days 7 and 14 of the test to prevent the build up of ammonia concentrations to toxic levels

- Aeration frequency and intensity: Loose plastic covers were placed over each test chamber. Each test chamber was gently aerated through a glass pipette that did not extend to a depth closer than 2 cm from the surface of the sediment. Air was bubbled into the test chamber at a rate greater than 1 bubble per second but not so great as to disturb the sediment. .

EXPOSURE REGIME

- No. of organisms per container (treatment): Four replicates were tested in each treatment group with 20 midges in each replicate for a total of 80 midges per treatment group.

- Type and preparation of food: A 28-day ration of food (280 mg Tetramin flake food) was dry mixed into the sediment prior to the addition of the overlying water and 49 hours before adding the test organisms.

OVERLYING WATER CHARACTERISTCS

- Dilution water source: Well Water

- Dilution water chemistry: hardness 136-144 mg/L as CaCO3 , alkalinity 178-180 mg/L as CaCO3 and conductivity 371-393 mhos/cm

OTHER TEST CONDITIONS

- Lighting (quality, intensity, and periodicity): fluorescent lighting with wavelengths similar to natural lighting, intensity was 414 lux at the surface of the water at test initiation, photoperiod was 16 hours light:8 hours dark with a 30-minute transition period.

The sediment contained 72% sand, 10% silt and 18% clay. Textural class: sandy loam. Organic carbon: 2.2%, Organic matter: 3.9%

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

166 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 84-435

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

84 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

development rate

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

39 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks on result:

other: 89 mg/kg dry weight, normalised to 5% organic carbon

Reported statistics and error estimates:

The 28-Day LC50 was calculated using the computer software of C.E. Stephan. The program is designed to calculate the LC50 value and 95% confidence interval by probit analysis, the moving average method, or binomial probability with nonlinear interpolation. In this study, the binomial method was used to calculate the LC50 value. The LC50 value was calculated using the mortality data collected at the end of the test. The no-observed-effect-concentration (NOEC) and the lowest-observed-effect-concentration (LOEC) were determined by visual interpretation of the dose-response pattern and statistical analyses of the mean development times, emergence ratios and development rates.

   Table 1. Results of analysis of sediment exposure concentrations

 

Nominal Test Concentration (mg/Kg)	Mean Measured Concentration (mg/Kg)	Mean Percent of Nominal
Negative Control	--	--
31	7.4	24
63	14	23
125	39	32
250	84	34
500	210	42
1000	435	44

 

 

Table 2. Test results

 

Mean Measured Concentration (mg/Kg)	Number Exposed	Percent Emergence	Percent Mortality	Mean Development Time (Days)	Emergence ratio	Development rate
Negative Control	80	88	13	17.7	0.88	0.0604
7.4	80	90	10	18.0	0.90	0.0588
14	80	94	6.3	17.4	0.94	0.0608
39	80	91	8.8	18.9	0.91	0.0588
84	80	71	29	20.3	0.71	0.0519*
210	80	43*	58	21.8*	0.43*	0.0486*
435	80	4*	96	23.8*	0.04*	0.0431*

^*There was a statistically significant difference (p<0.05) from the negative control using Dunnett’s t-test.

Validity criteria fulfilled:

yes

Conclusions:

A 28-Day LC50 value of 166 mg/kg dry weight has been determined for the effects of the sediment incorporated test substance on mortality of Chironomus riparius. A NOEC of 39 mg/kg dry weight for effects on development rate has been determined in the same test.

Reference 3

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2015-05-22 to 2016-05-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 225 (Sediment-Water Lumbriculus Toxicity Test Using Spiked Sediment)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 0005376712
- Expiration date of the lot/batch: 6 June 2016
- Purity: 98.3%, test date 27 June 2012

INTERNAL STANDARD - RADIOLABELLING INFORMATION
- Radiochemical purity: 90 to 100% (tested as 100%)
- Batch no. 26254-17
- Expiration date of radiochemical substance: 19 March 2019

Analytical monitoring:

yes

Details on sampling:

SEDIMENT
- Sampling interval: day 0, 7 , 28

PORE WATER- not sampled

OVERLYING WATER - not sampled

Vehicle:

yes

Remarks:

acetone

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Details of spiking: At day -3, 1.2 kg (equivalent to 0.90 L) wet weight of sediment was weighed in individual glass jars, followed by 2.7 L of fortified well water to give an approximate water volume to sediment volume ratio of 3:1. The jar contents were shaken manually to suspend the sediment immediately prior to dosing. Each jar was then dosed with 3.0 mL of the appropriate dosing stock solution. After settling overnight, the overlying water was decanted and 1.592 g of both Urtica powder and alpha cellulose (0.25% of the total sediment dry weight each) were weighed out and manually mixed into the sediment for each concentration as a supplemental food source for the test organisms. The final sediment dry weight following this addition was 0.6401 kg per concentration. The sediment was then allocated to the replicate test vessels.
- Controls: solvent, negative
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (stock solution and final test solution):
- Stock solution: 10 mg/mL
- Dosing stock solutions 6.80, 3.40, 1.70, 0.860, 0.420 mg/mL
- Evaporation of vehicle before use:

Test organisms (species):

Lumbriculus variegatus

Details on test organisms:

TEST ORGANISM
- Common name: Lumbriculus variegatus
- Source: laboratory cultures maintained at Smither Viscient


ACCLIMATION
- Acclimation period: 13 days following synchronisation
- Acclimation conditions (same as test or not): organisms were placed in an aquarium with test sediment and laboratory well water under flow-through conditions. Renewal of overlying water in holding aquarium with the fortified well water used in the test at a rate of approximately half a volume replacement per day.
- Type and amount of food: 15 mL of finely ground suspension of flaked fish food (100 mg/mL)
- Feeding frequency: weekly
- Health during acclimation (any mortality observed): none

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

120-180 mg/L as CaCO3

Test temperature:

19 to 22°C

pH:

overlying water: 7.1 to 8.2

Dissolved oxygen:

6.2 to 9.1 mg/L

Ammonia:

≤0.10 to 9.5 mg/L as N

Conductivity:

500-550 µS/cm

Nominal and measured concentrations:

nominal: 2.0, 4.0, 8.0, 16, and 32 mg/kg
measured: dosed sediment after mixing and prior to allocation to test vessels 1.3, 3.0, 4.5, 9.2, and 18 mg/kg
measured: mean measured concentrations during exposure period: 1.2, 2.8, 5.3, 9.5 and 17 mg/kg

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 600 mL clear glass beakers
- Sediment volume: 75 mL
- Sediment wet weight: 115g (average)
- Overlying water volume: 300 mL
- Depth of sediment and overlying water: sediment 1.5 cm, water 6 cm (ratio 1:4)
- Aeration: yes
- Aeration frequency and intensity: 1 to 3 bubbles per second
- Replacement of evaporated test water, if any:

EXPOSURE REGIME
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control / vehicle control: total of 6 control
- Feeding regime: added at start of test
- Type and preparation of food: Urtica powder and alpha cellulose added to sediment during sediment preparation



OVERLYING WATER CHARACTERISTCS
- Type of water (e.g. deionized, ground water, sea water, Elendt medium acc. to OECD 219): fortified well water
- Alkalinity: 88 mg/L as CaCO3
- Conductivity: 560 to 620 µS/cm

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Glen Charlie Pond, Wareham, Massachusetts. (SV Batch no. 042115-M-1-1)

HANDLING OF NATURAL SEDIMENT
- Storage conditions: under refrigerated conditions at approximately 4ºC

CHARACTERIZATION OF SEDIMENT
- Particle size distribution
- % sand: 91%
- % silt: 8%
- % clay: 1%
- %solids: 53.08%
- Sediment sieved: yes, wet pressed through a 2.0 mm sieve prior to use and characterisation
- pH dry matter and/or whole sediment: 5.6
- Ammonia content of pore water: 4.6 mg/L as N
- Total organic carbon (%): 2.5%
- Proof of absence of chemical contaminants: representative sample analysed for presence of pesticides, PCBs and toxic metals. None detected at concentrations considered to have an adverse impact on the test.

OTHER TEST CONDITIONS
- Light quality: fluorescent bulbs
- Photoperiod: 16 hours light, 8 hours darkness
- Light intensity: 390 to 490 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS
- Spacing factor for test concentrations: nominal concentrations chosen for the definitive study were 2.0, 4.0, 8.0, 16 and 32 mg/kg, based on sediment dry weight.

PRELIMINARY TESTING/EXPOSURE
- range-finding concentrations: nominal concentrations of 0.025, 0.17, 1.1, 7.5 and 50 mg/kg
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 3
- control / vehicle control: negative and solvent control sediments were maintained
- results: Statistical analysis determined no significant reduction in the mean number of surviving oligochaetes or in the biomass among oligochaetes exposed to any treatment level compared to the solvent control.

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 17 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Remarks on result:

other: ≥34 mg/kg dw normalised to 5% organic carbon

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 17 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 17 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Details on results:

- 29 oligochaetes was recovered in both the control and solvent control (pooled control = 29)
- mean biomass per replicate in the control and solvent control was 32 and 34 mg (pooled control = 33 mg)
- control and solvent control data met the minimum performance criteria of the guideline (i.e., population increase of ≥ 1.8)

At exposure termination (day 28), the mean number of surviving oligochaetes observed among the oligochaetes exposed to the 1.2, 2.8, 5.3, 9.5 and 17 mg/kg treatment levels was 29, 27, 27, 29 and 28, respectively, and mean biomass per replicate was 39, 36, 41, 38 and 43 mg, respectively. Statistical analysis determined no significant difference in mean number of surviving oligochaetes or biomass in any of the treatment levels tested compared to the pooled controls.

Validity criteria fulfilled:

yes

Conclusions:

No effects on survival or biomass have been reported when testing the registered substance at a loading rate of 17 mg/kg dwt sediment with Lumbriculus variegatus. Therefore 28-day NOEC and LC50 values of ≥17 and >17 mg/kg have been determined respectively in a sediment containing 2.5% organic carbon.

Reference 4

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

The experimental phase of the 28-day definitive test was conducted from 11 June to 13 July 2012 (dates encompass test substance application on day -2 to completion of the dry weight data collection at test termination)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

This study was conducted according to the appropriate OECD guideline, under GLP and analytical monitoring was carried out.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1735 (Whole Sediment Acute Toxicity of Invertebrates, freshwater)

Deviations:

yes

Remarks:

water quality range were slightly above (temperature of holding water), or below (pH of overlying water, DO%), however these were within the tolerance range of the animals and are not thought to affect the outcome of the study.

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

SEDIMENT

- Concentrations: all

- Sampling interval: Exposure concentrations of the test substance in sediment were measured on days 0 (test initiation), 7 and 28 (test termination)

- Sample storage before analysis: not reported


PORE WATER - discarded.


OVERLYING WATER - discarded

Vehicle:

yes

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT

- Details of spiking: A 20 mg/mL primary stock solution was prepared by placing 0.5097 g of the test substance (0.5000 g as active ingredient) into a 25-mL volumetric flask and bringing to volume with acetone. Appropriate amounts of the stock solution were taken and diluted with well water to give secondary stock solutions 17.6, 8.8., 4.4, 2.3 and 1.1 mg/ml solutions. 2 days prior to test initiation the test substance was applied to the sediment. For each treatment level 2 kg wwt (1.5 L, 0.879 kg dwt) sediment was added to a glass jar, along with 4.5 L water (1:3 sediment:water ratio). The jar contents were mixed by shaking to suspend the sediment prior to dosing. 5 ml of secondary stock solutions were used to achieve the nominal concentrations. Following dosing, the jars were shaken again to distribute the test substance. After settling overnight, the water was decanted and the treated sediments were allocated to the replicate test vessels for each exposure level.

- Equilibration time: 48 h

- Equilibration conditions: not reported

- Controls: dilution water

- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone

- Concentration of vehicle in test medium (stock solution and final test solution): 5.0 ml

- Evaporation of vehicle before use: the water of the stock solution was decanted


PREPARATION OF SPIKED WATER - not applicable

Test organisms (species):

Hyalella azteca

Details on test organisms:

TEST ORGANISM

- Common name: midge (freshwater amphipod)

- Source: Environmental Consulting & Testing, Superior, Wisconsin, USA

- Age of parental stock (mean and range, SD): not reported, received as 5 days old organisms

- Breeding conditions: not reported

- Handling of egg masses and larvae: not reported

- Age of animals at beginning of exposure: 10 days old

- Feeding during test

- Food type: combination of yeast, cereal leaves and flaked fish food suspension (YCT)

- Amount: 1.5 ml

- Frequency: daily


ACCLIMATION

- Acclimation period: 5 days

- Acclimation conditions (same as test or not): same conditions and holding water, though temperature was maintained at 25 °C

- Type and amount of food: 2.5 mL of YCT

- Feeding frequency: every other day

- Health during acclimation (any mortality observed): no mortality

Study type:

laboratory study

Test type:

semi-static

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

holding water: 64 to 70 mg/l as CaCO3

Test temperature:

range: 22 to 25 ºC

Dissolved oxygen:

range: 40 to 100%, with the exception of the solvent control on day 8. But this is not thought to have affected the outcome of the study.

Ammonia:

<0.65 mg/L

Nominal and measured concentrations:

Nominal concentrations: 0, solvent control, 6.3, 13, 25, 50 and 100 mg/kg dry weight
Mean measured concentrations:

Details on test conditions:

TEST SYSTEM

- Test container (material, size): 300 ml glass vessels. Each test vessel had a hole cut on the top edge of the beaker which was covered with 40-mesh Nitex® screen for drainage.

- Sediment volume: 100 ml (4cm layer)

- Weight of wet sediment with and without pore water: 121 g wet weight per vessel

- Overlying water volume: 175 ml

- Depth of sediment and overlying water: 275 ml

- Aeration: no

- Replacement of evaporated test water, if any: not reported


EXPOSURE REGIME

- No. of organisms per container (treatment): 10

- No. of replicates per treatment group: 12, 8 with test organisms 4 for chemical analysis

- No. of replicates per control / vehicle control: 12, 8 with test organisms 4 for chemical analysis

- Feeding regime: daily

- Type and preparation of food: combination of yeast, cereal leaves and flaked fish food suspension (YCT)

- Amount of food: 1.5 ml


RENEWAL OF OVERLYING WATER

- Details on volume additions: renewed by adding two volume additions (350 ml) per test vessel

- Flow-rate: 50 mL of water per cycle per vessel, 7 cycles per day


OVERLYING WATER CHARACTERISTCS

- Type of water: ground water

- Alkalinity: water hardness (CaCO3) of 64 to 70 mg/L

- Conductivity: 320 to 420 µS/cm

- Total organic carbon: 0.38 and 0.44 mg/L

- Unionized ammonia: 2.9 mg/l as nitrogen

- Total organophosphorous compounds: none detected


SOURCE OF NATURAL SEDIMENT

- Location and description of sampling site: Glen Charlie Pond, Wareham, Massachusetts, USA

- Contamination history of site: not reported


HANDLING OF NATURAL SEDIMENT: The sediment was obtained by removing the top 10 to 15 cm of sediment beneath a water depth of approximately 60 cm. The sediment was transferred from the collection site to Smithers Viscient in multiple 20-liter, sealed, polyethylene buckets where it was stored in a refrigerator at approximately 4 °C for 4 weeks prior to testing.


CHARACTERIZATION OF SEDIMENT

- Particle size distribution

- % sand: 93

- % silt: 4

- % clay: 3


- Moisture: percent moisture at 1/3 bar (water holding capacity) of 21.5%
.
- Presence of macrophytes/animals: not reported

- Further constituents

- Metals, organic compounds, petroleum hydrocarbons: None of these compounds were detected at concentrations that would be considered to have an adverse impact on the results of the test.

- Other: percent solids 43.93%.

- Sediment sieved: yes

- pH pore water: not reported

- pH whole sediment: 5.6

- Ammonia content of pore water: 2.9 mg/L as nitrogen

- Total organic carbon (%): 3.7%

- Total inorganic carbon (%):

- Proof of absence of chemical contaminants: yes


OTHER TEST CONDITIONS

- Photoperiod: 16 h light, 8h dark

- Light intensity: 510 to 910 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : all vessels were examined at test initiation and every 24 hours. Observations of mortality and abnormal behaviour were made and the physical characteristics of the test samples were recorded. At the endo f the study dry weight of surviving animals were also determined.


VEHICLE CONTROL PERFORMED: yes


TEST CONCENTRATIONS

- Spacing factor for test concentrations: 2

- Range finding study

- Test concentrations: 0.010, 0.10, 1.0, 10 and 100 mg/kg

- Results used to determine the conditions for the definitive study: no effects at the highest concentration tested.

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 68 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: survival and growth

Remarks on result:

other: ≥92 mg/kg dw normalised to 5% organic carbon

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 68 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: survival and growth

Duration:

28 d

Dose descriptor:

LC50

Effect conc.:

> 68 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: survival and growth

Reported statistics and error estimates:

Wilcoxon's Rank Sum Two-Sample Test (U.S. EPA, 2002) and Equal Variance Two Sample t-Test (U.S. EPA, 2002) were conducted on the survival and dry weight data to compare the performance of the control organisms with that of the solvent control organisms. During this study, the t-Test indicated no significant difference between control and solvent control data. Shapiro-Wilks’ Test (U.S. EPA, 2002) for normality was conducted. Bartlett’s Test (U.S. EPA, 2002) was conducted to check assumption of homogeneity. Dry weight met the assumption for normal distribution. Survival had non-normal distribution of data.
Survival treatment related effects were tested with Wilcoxon's Test with Bonferroni's Adjustment (U.S. EPA, 2002), dry weight treatment related effects were tested with Bonferroni's Adjusted t-Test (U.S. EPA, 2002).
CETISTM Version 1.8.4.20 (Ives, 2011) was used to perform the computations.

Validity criteria fulfilled:

yes

Conclusions:

No effects on growth and survival have been reported when testing the registered substance at a loading rate of 100 mg/kg dwt sediment (68 mg/kg dwt mean measured) with the freshwater amphipod Hyalella azteca. Therefore 28-day NOEC and LC50 values of ≥68 and >68 mg/kg have been determined respectively in a sediment containing 3.7% organic carbon.

Reference 5

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2015-05-22 to 2016-05-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 225 (Sediment-Water Lumbriculus Toxicity Test Using Spiked Sediment)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

SEDIMENT
- Sampling interval: day 0, 7 , 28

PORE WATER- not sampled

OVERLYING WATER - not sampled

Vehicle:

yes

Remarks:

acetone

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Details of spiking: At day -3, 1.2 kg (equivalent to 0.90 L) wet weight of sediment was weighed in individual glass jars, followed by 2.7 L of fortified well water to give an approximate water volume to sediment volume ratio of 3:1. The jar contents were shaken manually to suspend the sediment immediately prior to dosing. Each jar was then dosed with 3.0 mL of the appropriate dosing stock solution. After settling overnight, the overlying water was decanted and 1.534 g of both Urtica powder and alpha cellulose (0.25% of the total sediment dry weight each) were weighed out and manually mixed into the sediment for each concentration as a supplemental food source for the test organisms. The final sediment dry weight following this addition was 0.6167 kg per concentration. The sediment was then allocated to the replicate test vessels.
- Controls: solvent, negative
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium (stock solution and final test solution):
- Stock solution: 10 mg/mL
- Dosing stock solutions 6.20, 3.10, 1.54, 0.780, 0.400 mg/mL
- Evaporation of vehicle before use:

Test organisms (species):

Lumbriculus variegatus

Details on test organisms:

TEST ORGANISM
- Common name: Lumbriculus variegatus
- Source: laboratory cultures maintained at Smither Viscient


ACCLIMATION
- Acclimation period: 13 days following synchronisation
- Acclimation conditions (same as test or not): organisms were placed in an aquarium with test sediment and laboratory well water under flow-through conditions. Renewal of overlying water in holding aquarium with the fortified well water used in the test at a rate of approximately half a volume replacement per day.
- Type and amount of food: 12 mL of finely ground suspension of flaked fish food (100 mg/mL)
- Feeding frequency: weekly
- Health during acclimation (any mortality observed): none

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

92-160 mg/L as CaCO3

Test temperature:

18 to 22°C

pH:

overlying water: 7.1 to 8.4

Dissolved oxygen:

5.1 to 9.0 mg/L

Ammonia:

≤0.10 to 3.9 mg/L as N

Conductivity:

510-580 µS/cm

Nominal and measured concentrations:

nominal: 1.9, 3.8, 7.5, 15 and 30 mg/kg
measured: dosed sediment after mixing and prior to allocation to test vessels 1.7, 2.5, 6.0, 12 and 25 mg/kg
measured: mean measured concentrations during exposure period: 1.3, 2.7, 6.3, 12 and 19 mg/kg

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 600 mL clear glass beakers
- Sediment volume: 75 mL
- Sediment wet weight: 115g (average)
- Overlying water volume: 300 mL
- Depth of sediment and overlying water: sediment 1.5 cm, water 6 cm (ratio 1:4)
- Aeration: yes
- Aeration frequency and intensity: 1 to 3 bubbles per second
- Replacement of evaporated test water, if any:

EXPOSURE REGIME
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 4
- No. of replicates per control / vehicle control: total of 6 control
- Feeding regime: added at start of test
- Type and preparation of food: Urtica powder and alpha cellulose added to sediment during sediment preparation

OVERLYING WATER CHARACTERISTCS
- Type of water (e.g. deionized, ground water, sea water, Elendt medium acc. to OECD 219): fortified well water
- Alkalinity: 88 mg/L as CaCO3
- Conductivity: 560 to 620 µS/cm

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Glen Charlie Pond, Wareham, Massachusetts. (SV Batch no. 042115-M-1-1)

HANDLING OF NATURAL SEDIMENT
- Storage conditions: under refrigerated conditions at approximately 4ºC

CHARACTERIZATION OF SEDIMENT
- Particle size distribution
- % sand: 91%
- % silt: 8%
- % clay: 1%
- %solids: 51.13%
- Sediment sieved: yes, wet pressed through a 2.0 mm sieve prior to use and characterisation
- pH dry matter and/or whole sediment: 5.6
- Ammonia content of pore water: 3.9 mg/L as N
- Total organic carbon (%): 2.5%
- Proof of absence of chemical contaminants: representative sample analysed for presence of pesticides, PCBs and toxic metals. None detected at concentrations considered to have an adverse impact on the test.

OTHER TEST CONDITIONS
- Light quality: fluorescent bulbs
- Photoperiod: 16 hours light, 8 hours darkness
- Light intensity: 350 to 490 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS
- Spacing factor for test concentrations: nominal L5 concentrations chosen for the definitive study were 1.9, 3.8, 7.5, 15 and 30 mg/kg, based on sediment dry weight

PRELIMINARY TESTING/EXPOSURE
- range-finding concentrations: nominal concentrations of 0.025, 0.17, 1.1, 7.5 and 50 mg/kg
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 3
- control / vehicle control: negative and solvent control sediments were maintained
- results: Statistical analysis determined no significant reduction in the mean number of surviving oligochaetes or in the biomass among oligochaetes exposed to any treatment level compared to the solvent control.

Reference substance (positive control):

no

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 19 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Remarks on result:

other: ≥38 mg/kg dw normalised to 5% organic carbon

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 19 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 19 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

total number of worms

Remarks:

oligochaete biomass

Details on results:

- mean number of oligochaetes recovered in the control and solvent control was 30 and 27, respectively
- mean biomass per replicate in the control and solvent control was 37 and 30 mg, respectively
- control and solvent control data met the minimum performance criteria of the guideline (i.e., population increase of ≥ 1.8)

At exposure termination (day 28), the mean number of surviving oligochaetes observed among the oligochaetes exposed to the 1.3, 2.7, 6.3, 12 and 19 mg/kg treatment levels was 32, 24, 28, 25 and 24, respectively. Statistical analysis (Bonferroni’s Adjusted t-Test) determined a significant difference in the mean number of surviving oligochaetes in the 2.7 mg/kg treatment level compared to the pooled control (28 oligochaetes). Due to the lack of a dose response and lack of significant reductions at higher dose levels, the significant reduction determined for the 2.7 mg/kg was determined not to be treatment related.

Mean biomass per replicate in the 1.3, 2.7, 6.3, 12 and 19 mg/kg treatment levels was 33, 31, 31, 30 and 29 mg, respectively. Statistical analysis (Bonferroni’s Adjusted t-Test) determined no significant difference in mean biomass in any of the treatment levels tested compared to the pooled control (34 mg).

Validity criteria fulfilled:

yes

Conclusions:

No effects on survival or biomass have been reported when testing the registered substance at a loading rate of 19 mg/kg dwt sediment with Lumbriculus variegatus. Therefore 28-day NOEC and LC50 values of ≥19 and >19 mg/kg have been determined respectively in a sediment containing 2.5% organic carbon.

Reference 6

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2010-06-07 to 2010-07-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Stock solutions used to dose the exposure solutions were analysed at the approximate time of dosing. In addition, a sample of sediment from each treatment level and control were analysed prior to test initiation to confirm that the appropriate levels were achieved.

During the in-life phase of the definitive study, sediment samples were collected from each treatment level and control on day 0 (replicate E), day 7 (replicate F) and day 28 (replicate G). Overlying water from each replicate vessel was decanted and discarded. Pore water samples were collected by removing the entire sediment sample and centrifuging for 15 to 30 minutes at approximately 10,000 g. The resulting pore water was removed from the centrifuge tube and discarded. Sediment samples were collected with a stainless steel spatula from the centrifuge tubes, following centrifugation and removal of the pore water samples.

In addition, three quality control (QC) samples were prepared at each sampling interval and were stored and analysed with the set of study samples. These QC samples were prepared in sediment at concentrations of D6 similar to the treatment level range. Results of the analyses of the QC samples were used to judge the precision and quality control maintained during the analysis of sediment samples.

Vehicle:

yes

Details on sediment and application:

PREPARATION OF TREATMENT SOLUTIONS

A 200 mg/mL primary stock solution was prepared by placing 4.9996 g of D6 into a 25-mL volumetric flask and bringing it to volume with acetone (CAS No. 67-64-1). The resulting stock solution was observed to be clear and colourless with no visible undissolved test substance. Further treatment solutions were prepared by dilution. All solutions were observed to be clear and colourless with no visible undissolved test substance following preparation.

PREAPARATION OF TREATED SEDIMENTS

Application of the test substance (day -3) to the sediment occurred prior to the allocation of the sediment to the test vessels. Sediment jars were prepared by adding 1.5 kg of wet sediment (0.8154 kg dry weight based on a percent solids of 54.36%) followed by 4.5 L of laboratory well water and shaking to suspend sediment prior to dosing. Each test concentration was prepared individually by adding the appropriate dosing stock solution directly to each jar and shaking again following dosing to distribute the test substance.

Following settling for approximately 24 hours, water was decanted from the treated sediments and the sediments were allocated to the replicate test vessels for each exposure level. A solvent control sample was prepared in a similar manner as the treated sediment by adding 5.0 mL of acetone, containing no test substance, to 1.5 kg of wet sediment suspended in 4.5 L of laboratory well water. The negative control sediment consisted of 1.5 kg of unadulterated wet sediment suspended in 4.5 L of laboratory well water without the addition of solvent or test substance. Both the solvent and negative control sediments were also allowed to settle for approximately 24 hours after shaking. The water was then decanted from the control sediments and the sediments were allocated to the appropriate replicate test vessels.

Test organisms (species):

Chironomus riparius

Details on test organisms:

TEST ORGANISM

- Source: The midges used during this study were obtained from laboratory cultures maintained at Springborn Smithers. The culture water was laboratory well water and was characterized as soft water.

- Feeding: During rearing, the midge larvae were fed a finely-ground suspension of flaked fish food (i.e., 10 mg/mL). Midge larvae were fed daily during the culturing and rearing period.

- Test organism production: Prior to test initiation, egg masses were removed from culture aquaria and each individual egg mass was placed in a 30-mL plastic cup with approximately 25 mL of culture water. The egg masses were observed daily until hatching was complete (approximately 24 to 48 hours after release of egg masses by the female midges). Hatched midge larvae were transferred to a shallow glass bowl containing 1 L of culture water (laboratory well water) and 5 mL of the algae, Ankistrodesmus falcatus, to serve as a substrate. Midge larvae were reared under static conditions in laboratory well water. During the rearing of the midge larvae, the temperature ranged from 20 to 21 ºC and the dissolved oxygen ranged from 9.1 to 9.4 mg/L. The larvae were reared in the culture bowls for three days after hatching to provide first-instar larvae (3 days old) for use during the exposure to D6. No mortality of midge larvae was observed 48 hours prior to test initiation.

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

68 mg/L as CaCO3

Test temperature:

20 to 22 °C

pH:

4.2 to 7.3

Dissolved oxygen:

7.2 to 8.9 mg/L

Salinity:

Not applicable

Ammonia:

3.4 to 24 mg/L as N. Elevated ammonia levels at the end of the test are most likely due to increased microbial activity caused by continuous food addition to the test vessels coupled with a lack of midge larvae feeding activity. Since organism performance in these treatment levels exceeded the acceptability criteria, these elevated ammonia levels did not significantly impact the results or interpretation of the study.

Nominal and measured concentrations:

Nominal concentrations: 0 (Control), 0 (Vehicle control), 63, 130, 250, 500 and 1000 mg/kg dry weight.

Mean measured concentrations in treated sediments: 53, 88, 150, 320 and 620 mg/kg dry weight.

The results are interpreted with reference to mean measured concentrations.

Details on test conditions:

TEST SYSTEM

- Test vessels: The test vessels used were 600-mL clear glass beakers. The sediment and overlying water were added to the test vessels two days prior to test initiation. A 75-mL (approximately 1.5-cm layer) aliquot of sediment was added to each test vessel. The wet weight of the sediment in each test vessel averaged 120 g (65.2 g dry weight). A turbulence reducer, consisting of a modified plastic disk, was used to minimize the disruption of the sediment layer during the introduction of 300 mL (approximately 6 cm) of overlying water. The total medium volume (sediment/water) was maintained at 375 mL and the ratio of sediment to water was 1:4. The initial water level in each test vessel was marked in order to evaluate evaporation. Each test vessel was covered with a clear plastic plate to minimize evaporation and trap emerging adult midges.

- Sediment: The sediment (Springborn Smithers Batch No. 072009) used during this study was collected from Glen Charlie Pond, Wareham, Massachusetts. Prior to use and characterization, the sediment was wet-pressed through a 2.0 mm sieve to remove large particles. The sediment used in this study was characterized by Agvise Laboratories, Northwood, North Dakota, as having a percent organic carbon of 3.2%. The particle size distribution conducted by Agvise Laboratories resulted in an average particle size distribution of 88% sand, 10% silt and 2% clay. A sediment pH of 6.1 was also determined at Agvise Laboratories. A percent solids value of 54.36% was determined by Springborn Smithers Laboratories. In addition, a sample of sediment pore water was analysed prior to test initiation for ammonia concentration. The total ammonia concentration of the sediment pore water sample was 22 mg/L as nitrogen (ammonia). A representative sample of the sediment source was analyzed for the presence of pesticides, PCBs and toxic metals by GeoLabs, Inc., Braintree, Massachusetts. None of these compounds were detected at concentrations that would be considered to have an adverse impact on the results of the test.

- Overlying water: Overlying water used during this study was laboratory well water. The water used during the definitive exposure was characterized as having total hardness and total alkalinity as calcium carbonate (CaCO3) of 68 and 20 mg/L, respectively, a pH of 7.1, and a specific conductivity of 420 micromhos per centimetre (µmhos/cm).

- Replication: Four replicate exposure vessels (A through D) were established for each treatment level and control to monitor the biological results (i.e., percent emergence and development rate) of the exposed midges. Four additional replicate vessels (E through H) were established for each treatment level and control to determine exposure concentrations of D6 in the sediment.

- Test initiation: Application of the test substance (day -3) to the sediment occurred prior to the allocation of the sediment to the test vessels. Sediment jars were prepared by adding 1.5 kg of wet sediment (0.8154 kg dry weight based on a percent solids of 54.36%) followed by 4.5 L of laboratory well water and shaking to suspend sediment prior to dosing. Each test concentration was prepared individually by adding the appropriate dosing stock solution directly to each jar and shaking again following dosing to distribute the test substance.

Following settling for approximately 24 hours, water was decanted from the treated sediments and the sediments were allocated to the replicate test vessels for each exposure level. A solvent control sample was prepared in a similar manner as the treated sediment by adding 5.0 mL of acetone, containing no test substance, to 1.5 kg of wet sediment suspended in 4.5 L of laboratory well water. The negative control sediment consisted of 1.5 kg of unadulterated wet sediment suspended in 4.5 L of laboratory well water without the addition of solvent or test substance. Both the solvent and negative control sediments were also allowed to settle for approximately 24 hours after shaking. The water was then decanted from the control sediments and the sediments were allocated to the appropriate replicate test vessels.

At test initiation (day 0), twenty midge larvae (3 days old) were impartially added to each replicate test vessel (A through D). The additional replicates (E through G) established for chemical analysis of the sediment were maintained under the same test conditions as replicates A through D, but observations of midge emergence were not made on these vessels. Midges were added impartially to an intermediate beaker by adding no more than five midges to each vessel until all beakers contained five midges. This procedure was repeated until each intermediate beaker contained 20 midges. The test was initiated when each intermediate beaker of 20 midges was added to each respective test vessel. At the time of addition of the midge larvae, aeration of the water was suspended for 24 hours. The following day (day 1), aeration was resumed at 1 to 3 bubbles per second.

- Feeding: At test initiation (day 0), 1.0 mL of finely ground flaked fish food suspension (10 mg/mL) was added to each test vessel. Test midges were fed 1.0 mL of finely ground flaked fish food suspension (10 mg/mL) daily, on test days 0 through 10. On days 11 through termination, midges were fed 2.0 mL of finely ground flaked fish food suspension (10 mg/mL) daily.

- Observations: Replicate test vessels A through D were examined at test initiation and daily thereafter, until test termination (day 28). Observations of midge emergence and abnormal behaviour were made and the physical characteristics of the test solutions were recorded. During the period of expected emergence (typically starting at day 10 and lasting until day 28), a daily check of emerged midges was made. The sex and number of adult midges that emerged daily were recorded. Male midges were identified by their plumose antennae.

- Water quality: Water quality measurements made during the study were performed in the four replicate exposure vessels (A through D) established for monitoring the biological performance of the exposed midges. Measurements of dissolved oxygen concentration, temperature and pH were made on the day the test organisms were added (day 0) and at test termination (day 28) in each exposure vessel. In addition, dissolved oxygen concentration, pH and temperature were measured daily in an alternating replicate vessel of each treatment level and the controls during the remainder of the 28-day exposure. The temperature was continuously monitored in an auxiliary vessel in the water bath throughout the study. Total hardness, alkalinity, specific conductivity, and total ammonia of the test solutions were determined at test initiation and at test termination in a composite sample (replicates E through H on day 0 and replicates A through D on day 28) from the highest treatment level and the control solution.

- Range finding test: Prior to initiating the definitive study, a preliminary range-finding exposure was conducted at Springborn Smithers Laboratories at nominal D6 concentrations of 0.10, 1.0, 10, 100 and 1000 mg/kg, a control and a solvent (acetone) control. Three replicates of twenty midges (3 days old) were exposed to each treatment level and control. Following 28 days of exposure, the mean percent emergence among midges exposed to the nominal concentrations tested (0.10, 1.0, 10, 100 and 1000 mg/kg) was 98, 97, 95, 95 and 88%, respectively. During the same period, mean percent emergence among the midges exposed to the control and solvent control was 98 and 97%, respectively (pooled control = 98%). The mean development rate (male/female midge combined), after 28 days of exposure, for the nominal concentrations tested (0.10, 1.0, 10, 100 and 1000 mg/kg) was 0.0666, 0.0660, 0.0668, 0.0641 and 0.0575, respectively. During the same period, mean development rate among the midges exposed to the control and solvent control was 0.0633 and 0.0632, respectively (pooled control = 0.0632). Based on these results and consultation with the Study Sponsor, the following nominal D6 concentrations were selected for the definitive study: 63, 130, 250, 500 and 1000 mg/kg.

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 620 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: Midge emergence and development rate

Remarks on result:

other: ≥969 mg/kg dw normalised to 5% organic carbon

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 620 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: Midge emergence and development rate

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 620 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: Midge emergence and development rate

Reported statistics and error estimates:

At the termination of the study, data obtained on midge emergence and male and female development rate were statistically analysed to identify significant treatment-related effects. The lowest test concentration that showed a statistically significant effect (Lowest-Observed-Effect Concentration, LOEC) and the highest test concentration that showed no statistically significant effect (No-Observed-Effect Concentration, NOEC) were determined. All statistical analyses were conducted at the 95% level of certainty except in the case of Shapiro-Wilks’ Test (Weber et al., 1989) and Bartlett's Test (Sokal and Rohlf, 1981), in which the 99% level of certainty was applied. The 99% level of certainty is preferred for these qualifying tests.

CETIS-Comprehensive Environmental Toxicity Information SystemTM (Ives, 2009) Version 1.7 software was used to perform the computations. The results were used to establish, at the 95% level of certainty, the lowest test concentration that showed a statistically significant effect (Lowest-Observed-Effect Concentration, LOEC) and the highest test concentration that showed no statistically significant difference (No-Observed-Effect Concentration, NOEC) from the pooled control data.

Table 1. Results of analysis of test sediments

 

Nominal Concentration (mg/kg dry weight)	Measured Concentration (mg/kg dry weight)			Mean (Standard Deviation)^d	Percent of Nominal^d
	Day 0^a	Day 7^b	Day 28^c
Control	< 4.6	< 4.5	< 4.1	NA^e (NA)	NA
Solvent Control	< 4.6	< 4.5	< 4.1	NA (NA)	NA
63	37	74	48	53 (19)	84
130	86	96	82	88 (7.1)	68
250	120	160	160	150 (22)	59
500	270	380	320	320 (58)	64
1000	520	800	530	620 (160)	62

 

^a      Analytical samples were removed from replicate E of the additional exposure vessels. 

^b      Analytical samples were removed from replicate F of the additional exposure vessels.

^c         Analytical samples were removed from replicate G of the additional exposure vessels.

^d      Mean, standard deviation and percent of nominal were calculated using the original unrounded results and not the rounded (two significant figures) presented in this table.

^e      NA = Not Applicable.

 

 

Table 2. Test results

 

Mean Measured Sediment Concentration (mg/kg)	Test Day 28
	Mean % emerged	Mean Male/Female Combined Development Rate
Control	95	0.0670
Solvent Control	91	0.0707
Pooled Control	93	0.0689
53	93	0.0701
88	93	0.0720
150	95	0.0724
320	96	0.0719
620	90	0.0667

 

Validity criteria fulfilled:

yes

Conclusions:

A 28-d EC50 value of >620 mg/kg dry weight and a NOEC of >/= 620 mg/kg dry weight have been determined for the effects of the test substance on emergence and development rate of Chironomus riparius exposed to treated sediments. The results are expressed relative to mean measured exposure concentrations.

Description of key information

HMDS: A long-term study is available with HMDS for toxicity to Lumbriculus variegatus. Long-term studies are read-across from the structurally related substance L3 for Chironomus riparius and Hyalella azteca.

The data with Hyalella azteca (L3) and Lumbriculus variegatus (HMDS) show no effects at the highest concentrations tested in the studies. Significant losses from the test system were observed in the Lumbriculus variegatus study with HMDS. A true PNEC cannot be calculated from these test data because the NOEC values that have been determined are limit values. A 28-day NOEC of 39 mg/kg dry weight has been determined for effects of L3 on emergence and development rate of Chironomus riparius (89 mg/kg dry weight, normalised to 5% organic carbon).

 

L3: Long-term studies are available for three organisms (Chironomus riparius, Hyalella azteca and Lumbriculus variegatus) with L3. The data with Hyalella and Lumbriculus show no effects at the limit of solubility in organic carbon. Effects were observed in the Chironomus study. A 28-day NOEC of 39 mg/kg dry weight has been determined for effects of L3 on emergence and development rate of Chironomus riparius (89 mg/kg dry weight, normalised to 5% organic carbon). The organic carbon normalised value from this Chironomus study is selected as Key and used to derive PNECsediment.

 

L4: Long-term studies are available for two organisms (Hyalella azteca and Lumbriculus variegatus) with L4. The data show no effects at the limit of solubility in organic carbon. A true PNEC cannot be calculated from the test data because the NOEC values that have been determined are limit values. A study on Chironomus riparius with the closely related substance L3 has been read-across. A 28-d NOEC of 39 mg/kg dry weight has been determined for effects of L3 on emergence and development rate of Chironomus riparius (89 mg/kg dry weight, normalised to 5% organic carbon).

 

L5: A long-term study is available with L5 for toxicity to Lumbriculus variegatus. The data show no effects at the limit of solubility in organic carbon. Testing is proposed with L5 for a Chironomid toxicity test and possibly a further test with Hyalella azteca. In the interim, data from Chironomus riparius and Hyalella azteca are read-across from dodecamethylcyclohexasiloxane (D6; CAS 540-97-6) and decamethyltetrasiloxane (L4; 141-6-8), respectively.

The data currently available shows no effects at the highest concentrations tested in the studies. A true PNEC cannot be calculated from the test data because the NOEC values that have been determined are limit values. No hazard is identified.

Additional information

No data are available for toxicity of the whole substance to sediment dwelling organisms.

Available data have been read-across from each constituent of the multiconstituent substance.

Justification of read-across and comparison of physico-chemical properties is discussed in section 6 of IUCLID (Section 7.0 of the CSR).

It is possible to calculate the organic carbon (OC) solubility according to the following formula:

OC solubility mg/kg = Koc* water solubility

Constituent HMDS

A 28-d NOEC result for Lumbriculus variegatus is available for HMDS. A 28-d NOEC of ≥2.7 mg/kg dry weight (measured, arithmetic mean) has been determined for effects on oligochaete reproduction and biomass (≥4.5 mg/kg dry weight, normalised to 5% organic carbon) (Smithers Viscient, 2016). However, significant losses of the test material from the sediment were observed during the preparation of the test system and during the study period.

A 28-d NOEC result for Chironomus riparius is read across from L3. A 28-d NOEC of 39 mg/kg dry weight has been determined for effects on emergence and development rate of Chironomus riparius (89 mg/kg dry weight, normalised to 5% organic carbon) (Wildlife International, 2009).

A 28-d NOEC result for Hyalella azteca is read across from L3. A 28-d NOEC of ≥70 mg/kg dry weight has been determined for effects on survival and weight of Hyalella azteca (Smithers Viscient, 2016).

 

Constituent L3

A 28-Day LC₅₀ value of 166 mg/kg dry weight (377 mg/kg dwt normalised to 5% organic carbon (OC)) has been determined for the effects of the sediment incorporated test substance (L3) on mortality of Chironomus riparius. A NOEC of 39 mg/kg dry weight (89 mg/kg dwt normalised to 5% OC) for effects on development rate has been determined in the same test. The test was conducted under semi-static water replenishment conditions (Wildlife International, 2009).

A 28-day LC₅₀ and NOEC values of >70 and ≥70 mg/kg (>95 and ≥95 mg/kg dwt normalised to 5% OC) have been reported for the effects of L3 on the mortality and growth rate of the freshwater amphipod Hyalella azteca. The results are based on mean measured concentrations (Smithers Viscient, 2013).

A 28-day EC₅₀ value of >17 mg/kg sediment dry weight (>45 mg/kg dwt normalised to 5% OC) has been determined for the effects of L3 on survival and reproduction of Lumbriculus variegatus, using artificial sediment under flow-through water replenishment conditions (Smithers Viscient, 2013).

 

Constituent L4

A 28-day study has been conducted with L4 and Hyalella azteca. 28-day NOEC and LC₅₀ values of ≥68 and >68 mg/kg have been determined for the effects of L4 on mortality and growth of the freshwater amphipod Hyalella azteca in sediment containing 3.7% organic carbon (OC) (Smithers Viscient, 2013). The results normalised for a standard sediment of 5% organic carbon are equivalent to LC₅₀ and NOEC values of >92 and ≥92 mg/kg dry weight, respectively.

No effects on survival or biomass have been reported when testing L4 at a loading rate of 17 mg/kg dwt sediment with Lumbriculus variegatus. Therefore 28-day NOEC and LC₅₀ values of ≥17 and >17 mg/kg have been determined, respectively, in a sediment containing 2.5% organic carbon (Smithers Viscient, 2016). The results normalised for a standard sediment of 5% organic carbon are equivalent to LC₅₀ and NOEC values of >34 and ≥34 mg/kg dry weight, respectively.

A 28-d NOEC result for Chironomus riparius is read across from L3. A 28-d NOEC of 39 mg/kg dry weight has been determined for effects on emergence and development rate of Chironomus riparius (89 mg/kg dry weight, normalised to 5% organic carbon) (Wildlife International, 2009).

The results of all tests are expressed relative to mean measured exposure concentrations in the treated sediment.

 

Constituent L5

A 28-day study has been conducted with L5 using Lumbriculus variegatus. The registrants propose to conduct a Sediment-Water Chironomid Toxicity Test (OECD TG 218) with L5. Further testing using Hyalella azteca may also be conducted if necessary. In the interim, data from Chironomus riparius and Hyalella azteca are read-across from dodecamethylcyclohexasiloxane (D6; CAS 540-97-6) and decamethyltetrasiloxane (L4; 141-6-8), respectively.

No effects on survival or biomass have been reported when testing L5 at a loading rate of 19 mg/kg dwt sediment with Lumbriculus variegatus. Therefore 28-day NOEC and LC₅₀ values of ≥19 and >19 mg/kg have been determined respectively in a sediment containing 2.5% organic carbon. The results normalised for a standard sediment of 5% organic carbon are equivalent to LC₅₀ and NOEC values of >38 and ≥38 mg/kg dry weight respectively.

A result for effects in natural sediment on the invertebrate amphipod Hyalella azteca is read across from L4. The result from that test is a 28 d NOEC of ≥68 mg/kg sediment dry weight for growth rate (≥92 mg/kg sediment dry weight, normalised to 5% organic carbon). 

The following results are read-across from the structural analogue D6: A 28-d NOEC of ≥620 mg/kg dry weight have been determined for effects on emergence and development rate of Chironomus riparius (≥969 mg/kg dry weight, normalised to 5% organic carbon). 

The results of all tests are expressed relative to mean measured exposure concentrations in the treated sediment.