Pyrasulfotole

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14 Jan - 23 Apr 2008

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)

Version / remarks:

2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Ministerium für Arbeit, Gesundheit und Soziales des Landes Nordrhein-Westfalen, Düsseldorf, Germany

Analytical monitoring:

yes

Details on sampling:

Samples were taken from sediment, overlying water and pore water.
The concentration of the test item and its metabolite were analysed in sediment, overlying water and pore water.

SEDIMENT
- Concentrations: Control, 62.5, 125, 250, 500 and 1000 mg a.s./kg dw sed
- Sampling interval: three times on days 0, 7 and 28; additional measurements of sediment samples were made on day -1 for all test concentrations and the controls directly after sediment spiking
- Sample storage before analysis: frozen

PORE WATER
- Concentrations: Control, 62.5, 125, 250, 500 and 1000 mg a.s./kg dw sed
- Sampling interval: three times on days 0, 7 and 28
- Sample storage before analysis: frozen

OVERLYING WATER
- Concentrations: Control, 62.5, 125, 250, 500 and 1000 mg a.s./kg dw sed
- Sampling interval: three times on days 0, 7 and 28
- Sample storage before analysis: frozen

Vehicle:

yes

Remarks:

acetone

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Pooling or mixing of different substrates: 75.9% quartz sand (grain size: 79.1% of the particles were in the range of 50-200 μm, originated form Quarzwerke GmbH D-50226 Frechen, Germany), 4% sphagnum moss peat (pH 5.0-6.5, particle size of ≤ 1 mm, air dried, originated from Floragard Vertriebs GmbH D-26135 Oldenburg, Germany), 20% kaolinite (kaolinite content of 56 %, pH value 5.5 – 7.5, "Kaolin W", from Erbslöh / Geisenheim, Germany), 0.1 % calcium carbonate (chemical pure, Merck) to adjust the pH value to 7 ± 0.5 (figures refer to dry weight) and 45% deionised water.
- Method of mixing: The formulated sand was then mixed with the suitable amounts of sediment per test concentration by feed mixer. The bottom of the test vessels were covered with a 1.5 cm layer of wet sediment (corresponding to about 140 g). M7 medium was added as test water to the sediment layer. To avoid a separation of the sediment ingredients during this procedure, the sediment was covered by a sheet, and the test water poured slowly into the vessels (final test water volume: 0.38 L). The sheet was removed carefully thereafter.
- Details of spiking: One day before the start of the study (insertion of the larvae) spiked sediments of the test concentrations were prepared by addition of solutions of the test substance directly into the sediment. Stock solutions of the test substance dissolved in acetone were used. Suitable amounts of these stock solutions were mixed with suitable amounts of fine quartz sand for each test concentration (10 g / test vessel).
- Equilibration time: For equilibration the sediment had been prepared 7 days before spiking.
- Equilibration conditions: In case of a loss of water by evaporation, the test vessels were refilled with deionised water up to the mark, which indicates a volume of 0.38 L overlying water (typically once a week).
- Controls: yes (control and solvent control)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Evaporation of vehicle before use: The solvent was allowed to evaporate until it was as far as possible removed from sand

- Preparation of test solution: The test concentrations were set up as follows: 3.4836 g test substance were dissolved in 50 mL acetone (analytical grade) to obtain the Stock solution (S5). Afterwards several dilutions in acetone were made to obtain the stock solutions (S1 – S4) for each test concentration. The solutions were stirred on a magnetic stirrer for 10 minutes and the stock solution (S5) was additionally treated in an ultra-sonic bath for 3 minutes.. The spiked sediments were placed in the vessels, 4 x 140 g wet weight sediment /test concentration and test medium M7 was added up to a final water volume of 0.38 L to produce a sediment-water volume ratio of 1:4.
Detailed information are summarized within the Table 1 in section" Any other information on material and methods incl. tables"

Test organisms (species):

Chironomus riparius

Details on test organisms:

TEST ORGANISM
- Common name: non-biting midge
- Source: University of Frankfurt am Main (Germany)
- Details on collection: Transferred in July 2006 to the lab and kept since then.
- Age of parental stock: 2 to 3 weeks adults were mating and laid eggs on the water surface which were used for the test
- Breeding conditions: For breeding the midges are kept in cages (40 x 40 x 40 cm), with a gauze on each side of the cage. A glass basin (diameter 19 cm and 8 cm height) is set on the bottom of each cage. The bottom of the basins are covered with a thin layer of "Kieselgur" (silica) and a 4 - 5 cm high layer of reconstituted water M7 according to Elendt, which is aerated gently. The culture conditions are 20 ± 2 °C and 16 to 8 hours light-dark-cycle (light intensity ca. 500 - 1000 lux). Food: green algae and an aqueous suspension of a plant material based fish food (Tetra Phyll®)
- Handling of egg masses and larvae: The hatched larvae are fed with green algae and an aqueous suspension of a plant material based fish food (Tetra Phyll®). After 2 to 3 weeks the adults emerge. After mating, female adults will lay egg masses on the water surface where these can be taken to start a new culture or to perform toxicity tests.
- Age of animals at beginning of exposure: First instar (L1) of Chironomus riparius larvae. L1 larvae were obtained by introducing some fresh egg masses in small dishes with test medium. Two to three days after hatching the L1-larvae were transferred carefully with a blunt pipette to the test vessels.
- Feeding during test: yes
- Food type: commercial ornamental fish food extract (trade name Tetra Phyll®) as used for the breeding
- Amount: 0.25 mg Tetraphyll® /Larvae/day for the first 10 days and 0.5 mg Tetraphyll® /Larvae/day until the end of exposure was added to each test vessel
- Frequency: at least about three times per week

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

in overlaying water:
test start (0 d) 267.0 mg CaCO3/L and test end (28 d) 302.6 mg CaCO3/L (control)
test start (0 d) 267.0 mg CaCO3/L and test end (28 d) 302.6 mg CaCO3/L (1000 mg a.s./kg dw sed)

Test temperature:

in overlaying water:
test start (0 d) 20.2 °C and test end (28 d) 20.5 °C (control)
test start (0 d) 20.3 °C and test end (28 d) 20.5 °C (solvent control)
test start (0 d) 20.2 to 20.4 °C and test end (28 d) 20.2 to 20.5 °C (test concentrations)

pH:

in overlaying water:
test start (0 d) 8.1 and test end (28 d) 8.4 to 8.5 (control)
test start (0 d) 8.2 and test end (28 d) 8.4 to 8.5 (solvent control)
test start (0 d) 8.1 to 8.2 and test end (28 d) 8.4 to 8.5 (test concentrations)

Dissolved oxygen:

in overlaying water:
test start (0 d) 8.8 mg O2/L and test end (28 d) 8.2 to 8.6 mg O2/L (control)
test start (0 d) 8.8 mg O2/L and test end (28 d) 8.5 to 8.7 mg O2/L (solvent control)
test start (0 d) 8.7 to 8.8 mg O2/L and test end (28 d) 8.3 to 8.7 mg O2/L (test concentrations)

Ammonia:

in overlaying water:
test start (0 d) 0.65 mg ammonium/L and test end (28 d) 25.3 mg ammonium/L (control)
test start (0 d) 0.65 mg ammonium/L and test end (28 d) 27.9 mg ammonium/L (1000.0 mg a.s./kg dw sed)

Nominal and measured concentrations:

control, solvent control, 62.5, 125, 250, 500 and 1000 mg a.s./ kg sediment dw (initial nominal)

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 0.6 L glass beakers (Ø 9.5 cm)
- Sediment volume: The bottom of the test vessels were covered with a 1.5 cm layer of wet sediment (corresponding to about 140 g).
- Overlying water volume: Test water poured slowly into the vessels (final test water volume: 0.38 L).
- Depth of sediment and overlying water: The height of the water column was 6.0 cm.
- Aeration: yes
- Aeration frequency and intensity: Test vessels were aerated during the equilibration phase. The aeration of the water was stopped for 24 hours after insertion of test organisms and re-started 24 h later. Gentle aeration was provided through a glass Pasteur pipette situated about 2.5 cm above the sediment layer throughout the complete study over 28 days (approximately 2 bubbles per second). Test beakers were covered by clear plastic plates, preventing evaporation.
- Replacement of evaporated test water, if any: In case of a loss of water by evaporation, the test vessels were refilled with deionised water up to the mark, which indicates a volume of 0.38 L overlying water (typically once a week).

EXPOSURE REGIME
- No. of organisms per container (treatment): 20
- No. of replicates per treatment group: 4
- No. of replicates per control / vehicle control: 4
- Feeding regime: feeding during the test
- Type and preparation of food: commercial ornamental fish food extract (trade name Tetra Phyll®) as used for the breeding
- Amount of food: 0.25 mg Tetraphyll® /Larvae/day for the first 10 days and 0.5 mg Tetraphyll® /Larvae/day until the end of exposure was added to each test vessel
- Frequency: five times per week

RENEWAL OF OVERLYING WATER
- Details on volume additions: In case of a loss of water by evaporation, the test vessels were refilled with deionised water up to the mark, which indicates a volume of 0.38 L overlying water (typically once a week).

OVERLYING WATER CHARACTERISTCS
- Type of water: M7-medium was added as test water to the sediment layer. The medium was based on de-ionised water supplied by a central building for the Monheim Agrochemicals Center. The quality of the deionised water is checked at least twice (non-GLP data) a year for residues and contaminants (e.g. pesticides and heavy metals).
- Alkalinity: test start (0d) 71.2 mg CaCO3/L and test end (28 d) 195.8 mg CaCO3/L (control), test start (0d) 71.2 mg CaCO3/L and test end (28d) 195.8 mg CaCO3/L (1000 mg a.s./kg dw sed)
- Total organic carbon: <2 mg/L
- COD: < 5 mg/L
- Total solids: < 5 mg/L
- Residual chlorine < 0.01 mg/L
- Nh4+: < 0.03 mg/L
- Ag, Hg, Cd < 0.1 µg/L
- Al, As, Cr, Cu, Co, Fe, Pb, Ni, Zn: < 1 µg/L
- F-: < 100 µg/L
- Pesticide residue contaminants (54 tested): all < 0.05 µg/L
- Organochlorine contaminants (25 tested): all < 0.01 µg/L

CHARACTERIZATION OF artificial SEDIMENT
- % dry weight of sphagnum moss peat: 4% sphagnum moss peat
- kaolinite (%): 20
- quartz sand (%): 75.9
- calcium carbonate (%): 0.1
- deionised water (%): 45
- water content (%): 31.4
- organic carbon (%): 1.9
- pH-value: 6.7
- Method of preparation (if artificial substrate): Artificial sediment was used in the test, prepared 7 days before the start of the exposure period. The formulated sand was then mixed with the suitable amounts of sediment per test concentration by feed mixer.
- Maturation of artificial substrate (if any): yes
- Amount of pore water:
control: test start (0 d) = 21.2 g; day 7 = 23.0 g; day 28 = 22.2 g
solvent control: test start (0 d) = 20.9 g; day 7 = 24.7 g; day 28 = 21.0 g
test concentrations: test start (0 d) = 20.4 to 24.6 g; day 7 = 20.4 to 24.1 g; day 28 = 23.0 to 27.9 g
- Arsen (AS): 1 mg/kg
- Bismut (Bi): <1 mg/kg
- Cadmium (Cd): <1 mg/kg
- Chrom (Cr): 9 mg/kg
- Kupfer (Cu): 3 mg/kg
- Eisen (Fe): 1600 mg/kg
- Quecksilber (Hg): <0.05 mg/kg
- Mangan (Mn): 11 mg/kg
- Nickel (Ni): 2 mg/kg
- Blei (Pb): 9 mg/kg
- Palladium (Pd): < 1 mg/kg
- Platin (Pt): < 1 mg/kg
- Antimon (Sb): <1 mg/kg
- Zinn (Sn): 2.1 mg/kg

OTHER TEST CONDITIONS
- Photoperiod: 16 h light / 8 h darkness
- Light intensity: 673 lux

EFFECT PARAMETERS MEASURED: visual assessment of behavioural differences compared to the control. Daily recording of the sex, time point of emergence and number of emerged midges during the period of emergence. As only fully emerged adults are relevant for the endpoints of this study, larvae which did not yet mature were not taken into account for emergence ratios and development time. To determine number and sex of emerged adults, the covering plates of each test container were carefully moved and the midges, which mostly stayed at the sides of the vessels, were enumerated; after identification of the sex (male midges have feathered antennae) and removed.

VEHICLE CONTROL PERFORMED: yes

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.0
- Range finding study: no range-finding test was performed

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

250 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

emergence rate

Remarks on result:

other: pooled sex

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

500 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

emergence rate

Remarks on result:

other: pooled sex

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

emergence rate

Remarks on result:

other: pooled sex

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

development rate

Remarks on result:

other: pooled sex

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

> 1 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

development rate

Remarks on result:

other: pooled sex

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

development rate

Remarks on result:

other: pooled sex

Details on results:

- Total mass of test animals at beginning of test: 80
- No. of offspring produced: control: 76 emerged; solvent control: 71 emerged; 62.5 mg a.s./kg dw sed.: 69 emerged; 125 mg a.s./kg dw sed.: 68 emerged; 250 mg a.s./kg dw sed.: 71 emerged; 500 mg a.s./kg dw sed.: 61 emerged and 1000 mg a.s./kg dw sed.: 50 emerged
- No. of emerged male and female midges (per vessel and per day): Start of emergence was at day 15 to 16 for the controls and in all other test concentrations. 91.9 % of the inserted (n= 160) larvae maturated to adults in the controls after 28 days, fulfilling the guideline requirements
- No. of pupae failing to emerge (per vessel and per day): Abnormal observations throughout the study were only observed at the test concentrations of 125 and 1000 mg a.s. dw sed. On day 17 one midge failed to emerge and on day 24 and one dead pupae was found at test concentration of 125 mg a.s./dw sed. On day 22 and day 28 one midge failed to emerge, on day 24 and on day 25 one dead pupae were found at test concentration of 1000 mg a.s./dw sed.
- Percent emergence per replicate and test concentration: There was a statistical significant difference in emergence at the 500 and 1000 mg a.s./kg dw sed treatment levels as compared to the pooled controls, resulting in a NOEC of 250 mg a.s./kg dw sed..
- Mean development rate of fully emerged midges (per replicate and treatment rate; male and female midges pooled): For the development rate (pooled sex) there were no statistical significant differences as compared to the pooled controls up to the highest test concentration, resulting in a NOEC of ≥ 1000 mg a.s./kg dw sed.
- Sex ratio: No statistically different distribution between females and males were determined. Therefore males and females were pooled.

Reported statistics and error estimates:

ECx: ECx values (e.g. x = 15, 50) and confidence intervals after 28 days were calculated by probit (or logit, weibit, etc.) analysis or in case of failure by non-parametric-methods from the appropriate parameters (endpoints), using a commercial program.
LOEC: The LOEC determinations from the appropriate parameters (endpoints) were done, using the ANOVA procedure (α = 0.05, one sided) and properly selected multiple t-tests a commercial program. In case of a limit test (comparison of control and one treatment group only) the STUDENT t-test can be used.
NOEC: The no observed effect concentration (NOEC) is the test concentration immediately below the LOEC
SOFTWARE: Calculations were carried out using Microsoft Excel® spreadsheets. All further statistical evaluations were done using the commercial program ToxRat Professional.

Analytical Results:

During the study, the measured concentrations of the test item in the overlying water, pore water and sediment were analysed three times on days 0, 7 and 28 at all test levels and also in the control(s). Additional measurements of sediment samples were made on day -1 for all test concentrations and the controls directly after sediment spiking. Sediment analyses on day -1 (directly after spiking) reflect high recoveries of the test item with 107 to 121% (mean of 113%) of nominal concentrations in all test levels, thus all results are based on initial nominal concentrations of the test item in the sediment, expressed in mg a.s./kg dw sed. Chemical analyses were performed for the test item for sediment, overlying water and pore water samples. Sediment analyses on day -1 (directly after spiking) reflect high recoveries of the test item with 107 to 121% (mean of 113%) of nominal concentrations in all test levels, thus all results are based on initial nominal concentrations of the test item in the sediment, expressed in mg a.s./kg dw sed. Chemical analyses of the sediment, overlying water and pore water over time reflect the aquatic fate profile the test item with it partitioning out of the sediment into the water column overtime. Analyses of the sediment over time showed decreasing recoveries of 39% to 50% (mean = 46%) of nominal for all test concentrations on day 0. On day 7, 17% to 28% (mean = 23%) and on day 28, 14% to 20% (mean = 17%) of nominal were found, respectively. Analyses of the overlying water over time showed increasing recoveries of 26% to 28% (mean = 28 %) of nominal applied amount of a.s. per test concentration on day 0. On day 7, 58% to 64% (mean = 61%) and on day 28, 60% to 72% (mean = 68%) of nominal were found, respectively. Analyses of the pore water over time yielded in decreasing recoveries of 18% to 20% (mean = 19%) of nominal concentrations on day 0 for all test concentrations. On day 7, 5.6% to 7.6% (mean = 6.7%) and on day 28, 3.0% to 4.5% (mean = 4.1%) of nominal were found, respectively.

Table 1: Analyses of the sediment (day -1, 0, 7 and 28)

Initial nominal conc. of the test item [a.s.]	day	means of two analyses in mg/kg dw sed	Test item content in percent [%] of initial nominal
Control	-1	0
	0
	7	<LOQ*)
	28
Solvent control	-1		0
	0
	7
	28	<LOQ*)
62.5	-1	75.8	121
	0	31.1	50
	7	17.5	28
	28	11.2	18
125	-1	142	114
	0	59.9	48
	7	34.0	27
	28	20.7	17
250	-1	279	112
	0	115	46
	7	54.8	22
	28	34.6	14
500	-1	557	111
	0	197	39
	7	82.6	17
	28	73.2	15
1000	-1	1066	107
	0	464	46
	7	181	19
	28	196	20

*) The limit of quantitation (LOQ) of the method is 6.25 mg/kg dw sed

Table 2: Analyses in the overlying water (day 0, 7 and 28)

initial nominal conc. mg a.s./kg dw sed	analytical results of the test item in the overlying water (mg a.s./L)
	day 0	day 7	day 28
	analysed conc. mean of two analyses	analysed conc. mean of two analyses	analysed conc. mean of two analyses
	overlying water
control	< LOQ *)	< LOQ *)	< LOQ *)
solvent-control	< LOQ *)	< LOQ *)	< LOQ *)
62.5	4.10	9.16	10.6
125	8.60	19.6	22.8
250	17.8	39.6	45.3
500	35.9	79.2	88.2
1000	70.1	162	151

 

Table 3: Analyses in the pore water (day 0, 7 and 28)

	analytical results of the test item in the pore water 1) (mg a.s./L)
mg a.s./kg dw sed	day 0		day 7		day 28
	analysed conc. mean of two analyses		analysed conc. mean of two analyses		analysed conc. mean of two analyses
control	< LOQ *)	-	< LOQ *)	-	< LOQ *)	-
solvent-control	< LOQ *)	-	< LOQ *)	-	< LOQ *)	-
62.5	52.1	1.08 1)	16.4	0.33 1)	10.9	0.26 1)
125	103	2.22 1)	32.3	0.75 1)	22.4	0.52 1)
250	198	4.28 1)	74.9	1.81 1)	47.0	1.08 1)
500	385	9.47 1)	138	3.17 1)	79.2	1.99 1)
1000	869	17.7 1)	295	7.35 1)	103	2.87 1)

*) The limit of quantitation (LOQ) of the method is 1.010 mg/L for test item

1) = calculated to the real volume of pore water per test vessel.

Table 4. Total recovery of the test item per test vessel

Nominal test conc. in mg/ kg dw sed	day	Nominal total initial conc. in mg / test vessel (tv)	Sediment		Pore water		Overlying water		Whole test system
			measured conc. in mg /tv2)	[%] of nom. initial/ tv	measured conc. in mg /tv1)	[%] of nom. initial/ tv	measured conc. in mg /tv3)	[%] of nom. initial/ tv	Total meas. content in [%] of nominal initial/ tv
control	0,7,28	0	<LOQ	n.c.	<LOQ	n.c.	<LOQ	n.c.	n.c.
solvent contr.	0,7,28	0	<LOQ	n.c.	<LOQ	n.c.	<LOQ	n.c.	n.c.
62.5	0	6.00252)	2.99	49.7	1.08	18.0	1.56	26.0	93.7
	7		1.68	28.0	0.33	5.6	3.48	58.0	91.6
	28		1.07	17.9	0.26	4.4	4.03	67.1	89.3
125	0	12.0052)	5.75	47.9	2.22	18.5	3.27	27.2	93.6
	7		3.26	27.2	0.75	6.3	7.45	62.0	95.5
	28		1.99	16.6	0.52	4.3	8.66	72.2	93.0
250	0	24.012)	11.0	46.0	4.28	17.8	6.76	28.2	92.0
	7		5.26	21.9	1.81	7.5	15.0	62.7	92.1
	28		3.32	13.8	1.08	4.5	17.2	71.7	90.0
500	0	48.022)	18.9	39.4	9.47	19.7	13.6	28.4	87.5
	7		7.93	16.5	3.17	6.6	30.1	62.7	85.8
	28		7.03	14.6	1.99	4.1	33.5	69.8	88.6
1000	0	96.042)	44.6	46.4	17.7	18.5	26.6	27.7	92.6
	7		17.4	18.1	7.35	7.6	61.6	64.1	89.8
	28		18.8	19.6	2.87	3.0	57.4	59.7	82.3

1) calculated to the real volume of pore water per test vessel

2) nominal concentration calculated to the real amount of dry weight sediment per test vessel (140 g of wet weight spiked sediments with a mean water content of 31.4% were placed in each test vessel on day -1, resulting in 96.04 g dw sed /test vessel)

3) related to 380 mL overlying test water per test vessel

Emergence of males and females as dependent on conc. and time

Table 5: Cumulative emergence of Chironomus riparius males and females as dependent on concentration of the test item and time

Treatm. [mg a.s./kg dw sed]	control	solventcontr.	62,5	125	250	500	1000
0 d	0	0	0	0	0	0	0
10 d	0	0	0	0	0	0	0
11 d	0	0	0	0	0	0	0
12 d	0	0	0	0	0	0	0
13 d	0	0	0	0	0	0	0
14 d	0	0	0	0	0	0	0
15 d	1	1	2	1	0	0	1
16 d	11	7	8	7	6	6	5
17 d	23	18	23	20	12	16	16
18 d	30	27	28	28	25	25	26
19 d	42	36	35	40	33	36	33
20 d	59	48	45	48	45	45	43
21 d	69	59	58	53	49	52	48
22 d	73	66	63	59	57	56	49
23 d	76	69	68	65	64	57	50
24 d	76	69	68	67	65	58	50
25 d	76	70	69	68	69	59	50
26 d	76	71	69	68	70	60	50
27 d	76	71	69	68	70	61	50
28 d	76	71	69	68	71	61	50

Table 6: % Inhibition of development rate of males and females after 28 d

Treatm. [mg a.s./kg dw sed]	Mean	Std. Dev.	N	%Inhibition
Pooled Control	0.054	0.0019	8	0.0
62.5	0.055	0.0035	4	-0.3*)
125	0.054	0.0018	4	0.4
250	0.052	0.0033	4	3.8
500	0.054	0.0012	4	0.5
1000	0.055	0.0030	4	-2.6*)

*) negative inhibition values mean stimulation in the development rate

Table 7: Validity criteria for OECD 218

Criterion from the guideline	Outcome	Validity criterion fulfilled
The emergence in the control must be at least 70% at the end of the test.	The emergence in the control was 91.9% at the end of the test.	yes
C. riparius and C. yoshimatsui emergence to adults from control vessels should occur between 12 and 23 d after their insertion into the vessels. For C. tentans, a period of 20 to 65 d is necessary.	The emergence to adults from control vessels occured between 15 and 23 d after their insertion into the vessels.	yes
At the end of the test, pH and the dissolved oxygen concentration should be measured in each vessel. The oxygen concentration should be at least 60% of the air saturation value (ASV) at the temperature used and the pH of the overlying water should be in the 6-9 range in all test vessels.	The oxygen concentration was above 60% of the air saturation value and the pH was between 8.1 and 8.5 in the overlying water.	yes
The water temperature should not differ by more than ± 1.0 °C.	The water temperature did not differ by more than ± 1.0 °C.	yes

 

Validity criteria fulfilled:

yes

Remarks:

See Table 7 in "Any other information on results incl. tables".

Description of key information

NOEC (28 d) = 250 mg a.s./kg dw (Chironomus riparius, EPA OPPTS 850.1790, emergence ratio, nominal)

Key value for chemical safety assessment

EC50 or LC50 for freshwater sediment:

1 000 mg/kg sediment dw

EC10, LC10 or NOEC for freshwater sediment:

250 mg/kg sediment dw

Additional information

One experimental guideline study is available investigating the toxicity of the test item towards freshwater sediment organisms according to GLP. A long-term study was performed with the freshwater species Chironomus riparius (M-303715-01-2) according to OECD 218. First instar of Chironomus riparius larvae, 4 beakers per test concentration, control and solvent control with 20 animals each) were exposed in a static test system for 28 days to initial nominal concentrations of 62.5, 125, 250, 500 and 1000 mg a.s./ kg dw sed (dry weight sediment) of a water-sediment system. The concentration of the active substance Pyrasulfotole was analysed in the freshly prepared spiked sediments of all test concentrations and the controls on day -1. Moreover the test item concentrations were analyzed at day 0 (directly before inserting of the larvae), day 7 and day 28 (after insertion of the larvae) in the overlying water, the pore water of the sediment and the sediment in additionally prepared test vessels. Chemical analyses were performed for the test item for sediment, overlying water and pore water samples. Sediment analyses on day -1 (directly after spiking) reflect high recoveries of the test item with 107 to 121% (mean of 113%) of nominal concentrations in all test levels, thus all results are based on initial nominal concentrations of the test item in the sediment, expressed in mg a.s./kg dw sed. Chemical analyses of the sediment, overlying water and pore water over time reflect the aquatic fate profile the test item with it partitioning out of the sediment into the water column overtime. Analyses of the sediment over time showed decreasing recoveries of 39% to 50% (mean = 46%) of nominal for all test concentrations on day 0. On day 7, 17% to 28% (mean = 23%) and on day 28, 14% to 20% (mean = 17%) of nominal were found, respectively.Analyses of the overlying water over time showed increasing recoveries of 26% to 28% (mean = 28%) of nominal applied amount of a.s. per test concentration on day 0. On day 7, 58% to 64% (mean = 61%) and on day 28, 60% to 72% (mean = 68%) of nominal were found, respectively. Analyses of the pore water over time yielded in decreasing recoveries of 18 % to 20% (mean = 19%) of nominal concentrations on day 0 for all test concentrations. On day 7, 5.6% to 7.6% (mean = 6.7%) and on day 28, 3.0% to 4.5% (mean = 4.1 ) of nominal were found, respectively.Start of emergence was at day 15 to 16 for the controls and in all other test concentrations.91.9% of the inserted (n= 160) larvae maturated to adults in the controls after 28 days, fulfilling the guideline requirements.Statistical tests indicates no statistically different distribution between sexes compared to the assumption of 50% females and 50% males. Therefore male and female results were pooled for further statistical analyses to increase the statistical power. There was a statistical significant difference in emergence at the 500 and 1000 mg a.s./kg dw sed treatment levels as compared to the pooled controls, resulting in a NOEC of 250 mg a.s./kg dw sed. For the development rate (pooled sex) there were no statistical significant differences as compared to the pooled controls up to the highest test concentration, resulting in a NOEC of ≥ 1000 mg a.s./kg dw sed. Allendpoints were evaluated based on the nominal initial concentration of the test item.