2-chloro-N-[[[4-(trifluoromethoxy)phenyl]amino]carbonyl]benzamide

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:

Study initiated/completed: 29 August 1995 - 26 September 1995.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

This study was carried out in a GLP-certified laboratory and in adherence with BBA (proposed method, 1996) guidelines. No deviations occurred from these guidelines.

Qualifier:

according to guideline

Guideline:

other: BBA

Version / remarks:

1996

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

For acclimatization the test containers were prepared 8 days before the study commenced. One day prior to treatment (= day -1) the test organisms (LI-larvae) were transferred in a randomized procedure into the test containers (collectives of five larvae each). On day 0 the test substance was applied to the water. During the study the larvae were fed at least about three times per week. The test vessels were also observed at least three times per week to make a visual assessment of any behavioral differences compared to the control. The sex, time and number of emerged midges was recorded daily during the period of emergence. As only fully emerged adults are relevant for the endpoints of this study, larvae which did not mature were not evaluated.

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) midges were removed.

Vehicle:

not specified

Details on sediment and application:

The test sediment used was artificial sediment which was prepared 11 days before the start of the test. It consists of 69 % fine quartz sand (84 % of the sand has a particle size of 0.06 - 0.2 mm), 10 % dried, finely ground peat (sphagnum peat; pH 2 - 4), 20 % kaolin (kaolinite content of about 36 %, pH value ca 7, "Kaolin W", from Erbsloh / Geisenheim) and around 1% calcium carbonate (pure) to adjust the pH value to 6 ± 0.5 (figures refer to dry weight). The bottom of the test containers were covered with a 2 cm high layer of sediment. To avoid a separation of the sediment ingredients when filling the test water, the sediment was covered by a sheet, before the test water was slowly poured into the beaker (the beakers were filled with 2.65 1 water). The sheet was carefully removed thereafter. The height of the water was 20 cm. Gentle aeration was provided through a glass Pasteur pipette situated about 2.5 cm above the sediment layer. Test beakers were covered by clear plastic plates.

The range of test concentrations were selected so as to get the EC15. The following initial nominal test concentrations were chosen: 0.10, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6 and 10 µg a.s./L. The test concentrations were set up as follows: 26.9 mg test substance was given ad 100 mL acetone (p. A.). Of this acetone solution, 2 mL were made up to 1000 mL test water to get stock solution I and 0.2 mL acetone solution were made up to 1000 mL with test water to get stock solution II. In order to reach the concentrations of 10, 5.6, 3.2 and 1.8 µg a.s./L appropriate volumes of stock solution I were applied into the overlying water column of one beaker. The suspension (9 to 50 mL) was applied just below the water surface by using a pipette and gently mixing the water to ensure homogeneous distribution without disturbing the sediment. For the test concentrations of 1.0, 0.56, 0.32, 0.18 and 0.10 µg a.s./L appropriate volumes of stock solution II were applied in the same way (5 to 50 mL). In order to prepare the solvent control 1.0 ml acetone was solved in 100 mL test water. 10 mL of this solution were applied into the overlying water column of one beaker (= 0.04 mL acetone/L, corresponding to the highest concentration of acetone in the test concentrations). For biological evaluations three replicates were prepared of the control, solvent control and one replicate for each test concentration. For chemical analysis of the active ingredient additional parallel replicates were prepared for analytical purposes only (control and solvent control: 1 replicate, 0.32, 1.8 and 10 µg a.s./L: 2 replicates).

Test organisms (species):

Chironomus riparius

Details on test organisms:

For the study, animals of the first larval stage (L1), the parents of which stem from an approximately 21-28 day old synchronous culture, were used. Twenty-five larvae were placed in each test container (3l glass beakers). For the breeding the midges are kept in cages (60 x 60 x 55 cm), with a gauze on the sides of the cage. A basin (45 x 55 x 10 cm) made of inert plastic is set on the bottom of each cage. The bottom of the basins are covered with a thin layer of "Kieselgur" (silica) and a 2 - 3 cm high layer of reconstituted water M7 according to Elendt, which is gently aerated. To start the culture in a cage, 2 - 4 egg masses are placed into the prepared basin. The hatched larvae are fed with green algae and an aqueous suspension of a vegetable fish food. After 2- 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.

The LI larvae used in the study were obtained by introducing some fresh egg masses in small dishes with culture medium. Two to 3 days after hatching the L1-larvae were transferred carefully with a blunt pipette to the test vessels. The aeration of the water was stopped for 24 hours after inserting of test organisms.

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Remarks:

M7-medium

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Test temperature:

20 ± 2°C

pH:

pH of freshly prepared test water: 7.91

Dissolved oxygen:

Dissolved oxygen in freshly prepared test water: 8.4 mg/L.

Conductivity:

Conductivity of freshly prepared test water: 600 µS/cm

Nominal and measured concentrations:

During the study, the measured concentrations of triflumuron (tech.) in the test water were analyzed three times at the initial nominal concentrations of 0.32, 1.8 and 10 µg a.s./L. The analytical results for the two stock solutions on day 0 were only 13 and 72 % of nominal, caused by the low solubility of triflumuron in water (25 µg/L). Nevertheless, the results of the test concentrations 0.32, 1.8 and 10 ng AI/1 were 95 to 123 % of nominal (on average 111%) 1 hour after application. These findings prove that the initial concentrations of this study were prepared correctly and nominal concentrations can be used to calculate EC values.

Details on test conditions:

The animals in the test containers were exposed to a temperature of 20 ± 2°C and a 16 : 8 hours light-dark cycle (including 1/2 hour dusk and dawn) in an environmental chamber. Light intensity has been determined with a LMT "pocket-lux" and was on average about 1500 lux.

Key result

Duration:

28 d

Dose descriptor:

other: EC15

Effect conc.:

0.32 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: Range: 0.01-0.69 µg/L

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

1 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: Range: 0.38-6.03 µg/L

Key result

Duration:

28 d

Dose descriptor:

other: EC15

Effect conc.:

> 1.8 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks on result:

not determinable

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1.8 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks on result:

not determinable

Details on results:

The concentrations of the test item in the overlying water declined continuously during the study: 2.8 and 22.5 % of nominal were found on day 7 at the test concentrations of 1.8 and 10 µg a.s./L. On day 28, the AI content of these concentrations was lower than the detection limit of 0.05 µg a.s./L, same as in the test concentration of 0.32 µg a.s./L on days 7 and 28. These findings
demonstrate that the test substance fully adsorbed to the sediment and/or degraded during the study.

As revealed by the physico-chemical measurements during the study, the test water quality was not influenced by the treatment with the test substance.
The %-emergence of midges in the control fulfilled the guideline requirements: 81 % of the inserted larvae maturated to adults. The X squared established for test concentrations with full emergence (0.10 - 1.0 µg a.s./L) only for the concentration of 1.0 µg a.s./L different numbers of emerged midges per sex (P = 0.05). Because it is not possible to introduce the same number of female and male organisms as larvae into each test beaker, the emergence rate of male and
female numbers are pooled for the statistical analysis. Probit analysis was performed to calculate the EC15 and EC50 for numbers of emerged midges.

The day of first emergence was not postponed at any test concentration with successful emergence (0.10 to 1.0 µg a.s./L). At test concentrations higher than 1.8 µg a.s./L no adult midges emerged. Out of the test concentrations with full emergence only 1.8 µg a.s./L affected the development rate: the average development time of 18.5 days was 11.4 % longer than the control (16.6 days). Thus, a probit analysis of the development rate is not possible, and the EC15 and EC50 for female and male organisms as well as for the sum of both sexes is given as > 1.8 µg initial nominal a.s./L.

Table 1 - Influence on the emergence and development after 28 days

Initial concentration mg a.s./L	No. of emerged midges	Emergence (%) of inserted larvae	% male of emergence	% female of emergence	Development (pooled sex) Time (d)	Development (pooled sex) Rate (1/d)
Control	61	81.3*	47.5	52.5	16.6±0.25	0.060±0.001
Solvent Control	65	86.7*	61.5	38.5	16.1±0.10	0.062±0.000
0.10	23	92.0	52.2	47.8	16.6	0.060
0.18	24	96.0	54.2	45.8	16.5	0.060
0.32	18	72.0	50.0	50.0	16.6	0.060
0.56	22	88.0	45.5	54.5	16.5	0.060
1.0	20	80.0	75.0	25.0	16.7	0.060
1.8	5	20.0	80.0	20.0	18.5	0.054
3.2	0	-	-	-	-	-
5.6	0	-	-	-	-	-
10	0	-	-	-	-	-

* related to 3 beakers with 25 larvae each; in all other cases related to 1 beaker

Validity criteria fulfilled:

yes

Conclusions:

Chironomus riparius were exposed to nominal initial test material concentrations of 0.10, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6 and 10 µg/L. Test material concentrations were measured on Days 0, 7 and 28 and were found to be 111 (95-123) % of nominal. No emergence of adult midges was seen at >1.8 µg/L. Development time compared to controls was delayed by 11.4% at 1.8 µg/L but not at lower concentrations.

Executive summary:

In the static test, the EC₁₅ (Probit analysis) for numbers of emerged midges was 0.32 µg initial nominal a.i/L (confidence limits 0.01 - 0.69 µg a.s./L), the EC₅ 0.17 µg a.s./L (0.00 - 0.42 µg a.s./L), the EC₁₀ 0.25 µg a.s./L (0.00 - 0.56 µg a.s./L) and the EC₅₀ 1.0 µg a.s./L (0.38 - 6.03 µg a.s./L). The gradient of the line of regression (after Litchfield & Wilcoxon) was s = 2.98. The day of first emergence was not postponed at any test concentration with successful emergence (0.10 to 1.0 µg a.s./L).

At test concentrations higher than 1.8 µg a.s./L no adult midges emerged. Out of the test concentrations with full emergence only 1.8 µg a.s./L affected the development rate: the average development time of 18.5 days was 11.4 % longer than the control (16.6 days). Thus, a probit analysis of the development rate is not possible, and the EC₁₅ and EC₅₀ for female and male organisms as well as for the sum of both sexes is given as > 1.8 µg initial nominal a.s./L.

Description of key information

Triflumuron was tested to determine the effects on emergence and development of Chironomus riparius larvae in sediment. 81 % of larvae maturated to adults in the control. The emergence or development rate was not effected at the concentrations of 0.1 – 1.0 µg a.s./L. At 1.8 µg a.s./L, decrease of emergence and longer development were observed. At concentrations higher than 1.8 µg a.s./L, no midges emerged. 

The EC50 (emergence) is 1 µg a.s./L nominal.