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

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

July 12 1990 - December 4 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

2000

Deviations:

yes

Remarks:

Please see principles of method if other than guidelines section

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Version / remarks:

1996

Deviations:

yes

Remarks:

Please see principles of method if other than guidelines section

Principles of method if other than guideline:

The test was performed according to the OECD Guideline No. 202 (Guideline for Testing of Chemicals, "Daphnia sp., Acute Immobilisation Test and Reproduction Test, Part I - The 24h EC50 Acute Immobilisation Test, adopted 04. April 1984") with the exception that the test duration was extended to 48 hours, this study corresponds with the draft document of October 2000 and the EEC Directive 92/69/EWG, part C.2. The test also meets the requirements of EPA FIFRA Guideline 72-2 "Acute Toxicity Test for Freshwater Invertebrates" and of the public draft of OPPTS Series 850.1010 (1996), with some minor modifications (e.g. loading rate was one animal in 5 ml and no transition photo period was integrated in light-dark-cycle), which are considered to have no impact on the outcome of the study.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The definitive test levels used in this test were based on an earlier 48-hours acute range finding pre-test with Daphnia magna and the same test substance. The animals in this static acute test were exposed to a dilution water control and the nominal concentrations of 0.1, 1.0, 10 and 100 µg a.s./L (20 animals per concentration).

The animals in the definitive test were exposed to a dilution water control, a solvent control (0.1 mL DMF/L) and the nominal concentrations of 0.10, 0.22, 0.48, 1.1, 2.3, 5.2, 11.4, and 25 µg a.s./L.

Vehicle:

yes

Remarks:

DMF (Dimethyl formamide solvent vehicle)

Details on test solutions:

For the test, 12.6 mg of the test item with a purity of 99.4 % were suspended in 50 mL DMF (= stock solution for dilution of stock solutions and also highest stock solution for preparation of the test concentrations in water). This solution was stirred with a magnetic stirrer for 5 minutes and placed in an ultra sonic bath for approximately 30 seconds. The concentration of the test item in this stock solution was 0.25 g/L. From this stock solution 11.4, 5.2, 2.3, 1.10, 0.48, 0.22 and 0.10 mL were taken and replenished with DMF to 25 mL each in order to prepare the needed stock solutions for adding the test item to the test water. Nominal concentrations in this stock solutions were 0.114, 0.052, 0.023, 0.011, 0.0048, 0.0022 and 0.0010 g test item/L. From each of this stock solutions, containing 0.0010 to 0.25 g/L, 200 µL were taken and added to 2000 mL of test water to achieve the nominal test concentrations of 0.10, 0.22, 0.48, 1.1, 2.3, 5.2, 11.4, and 25 µg/L. Each concentration was stirred on a magnetic stirrer for 5 minutes. The solvent control was prepared by adding 200 µL of DMF without test item to 2000 mL test water.

Test organisms (species):

Daphnia magna

Details on test organisms:

To perform the test, first instars (Daphnia magna, strain from the Bundesgesundheitsamt in Berlin, Germany), < 24 hours old, were exposed to various test concentrations. The clone was classified as genotype No. 2 by Dr. Bradley, University of Sheffield, Department of Zoology, report of February 3, 1988. This clone was renamed later as "type B" according to BAIRD, D.J. et al. (1). This strain has been maintained in the laboratory for more than ten years. The water they are kept in is changed weekly (dilution water, see below). The organisms are kept in 2-L containers (50 to 100 daphnids per container) in an environmental chamber under test conditions: 20 ± 1 °C; 16 : 8 hour light-dark cycle. The animals are fed with an aqueous suspension of 5 mL single cell green algae Scenedesmus subspicatus three times per week per container. The animals occasionally receive some commercial ornamental fish food (trade name: TetraMin®) (aqueous suspension) as a supplement to the algae diet (2 mL per container). The first instars used in the test were obtained by repeated careful screening of adults using plastic screens with 0.6 and 0.2 mm mesh. The parent daphnids were of the same age (±12 hours). They were between 21 and 28 days old. The organisms used during the exposure were < 24 hours old and were from the fourth brood or later. No males, ephippia or discoloured animals were present in the cultures. The cultures showed no delay in first brood.

Test type:

semi-static

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

At the start of the study, ten < 24 hours old first instars were carefully transferred into each test beaker using a pipette. All organisms were transferred into the test chambers as fast as possible after preparation of the test solutions. The animals we

Test temperature:

20.3-20.5

pH:

pH in test solutions at 0, 24 hours: 7.9-8 and 8.1-8.2 respectively (Day 0).

pH in test solutions at 0, 24 hours: 8 and 8.0-8.1 respectively (Day 1).

Dissolved oxygen:

Oxygen concentrations in test solutions at 0, 24 hours: 8.0-8.5 mg/L and

Nominal and measured concentrations:

Nominal concentrations were 0, 0.10, 0.22, 0.48, 1.1, 2.3, 5.2, 11.4 and 25 µg/L. Measured concentrations of the test item were 88 to 130% (on average 110%) of nominal throughout the study period.

Details on test conditions:

Test system and procedure:
The exposure of Daphnia magna to Triflumuron (tech.) was conducted for 48-hours under semistatic conditions. At 0 hours and at 24 hours test solutions were freshly prepared as described below. After 24 hours the test animals were gently transferred to the newly prepared test solutions with a few drops of the old test solutions using a pipette. Any apparatus in contact with the test solution was made of glass or other chemical inert material. The test vessels consisted of 100 mL glass beakers, labelled with a study number, concentration and replicate. Each test vessel contained 50 mL of the test solution with ten animals per vessel (1 daphnid / 5 mL), three replicates per concentration. The beakers were covered with a plexiglas plate and placed in an environmental chamber between 18 and 22 °C (should be constant within ± 1 °C for each single test) and a 16:8 hours light-dark cycle.

The test period was 48 hours. The water fleas were not fed, and the test solutions were not aerated during the test. The light intensity was at least measured twice a year, and as no changes in the illumination of the chamber is performed, unless necessary, the light intensity was about 1500 lux. After 24 and 48 hours, the water fleas were visually evaluated by counting survivors (= animals with swimming movements (slight movements of antennae were not interpreted as swimming movement) within approximately 15 seconds after gentle agitation of the test vessel). Additional observations for sublethal effects were also made.

Chemical and physical measurements:
Total hardness, alkalinity and conductivity were measured at the beginning of each 24 hour exposure period in the dilution water control. The pH and dissolved oxygen were measured in the control, solvent control and every test concentration at each test concentration preparation (0 and 24 hours) in the freshly prepared test solutions. Additionally these parameters were measured in the test solutions after the corresponding 24 hours exposure period (day one and day two of this study). Temperature was measured at the start and the end of the study in one vessel of the control and one vessel of the highest test concentration by an electronic thermometer, testo model 112. Additionally, air temperature was recorded continuously in the environmental chamber by a thermohygrometer. The pH was measured by an electronic Knick calimatic 766 pH meter, dissolved oxygen was measured by a WTW oxygen meter model 537 and conductivity was measured by a KNICK Portamess Cond. conductivity meter. Alkalinity and total hardness were analysed by titration using an Aquamerck® measuring kit.

Dilution water: Test and breeding water was prepared as "M7-medium" as documented in the "Original Draft" of an EEC Daphnia magna Pilot Ring Test. The "M7-medium" is similar to the "M4-medium" which was described by B.-P. ELENDT and W.-R. BIAS (2). The medium is prepared using deionized water by adding mineral salts and vitamins (reagent grade chemicals). The conductivity of the deionized water used in this test was below 10microS/cm. The water was aerated and tempered to 20 °C in an inhouse preparation apparatus (1200-L tank). The nominal conductivity of the reconstituted water was 580 microS/cm (= micro mhos/cm). The Ca:Mg ratio is 7:1, and the Na:K ratio is 6: 1.

Reference substance (positive control):

yes

Remarks:

An acute toxicity test was performed on October 10, 2001 under the same conditions using the reference substance K2Cr2O7, reagent grade.

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

13 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.6 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Neither immobility above 10 % nor any occurrence of symptoms have been observed at concentrations up to 0.22 µg a.s./L after 24 and 48 hours (NOEC). The lowest concentration showing mortality above 10 % was 0.48 µg a.s./L after 24 and 48 hours (LOEC). There was no concentration causing 100 % immobility. Highest observed immobility was 83 % at 25 µg a.s./L (nominal water solubility of the a.s.) after 48 hours.

Reported statistics and error estimates:

The EC50-values and the 95 percent confidence limits were calculated by an EC50 computer program developed by Dr. H.T. Ratte (Technical University Aachen) using the Probit-Analysis after the "Maximum-Likelihood" Method (according to Finney, 1978).

At the start of the study, the following parameters of the test water were determined: conductivity: 583 uS/cm, total hardness: 10° dH (= 178 mg/L CaCOS) and alkalinity: 3° dH (= 50 mg/L CaCOS equivalent to 1 mL 0.1 N HCI). On the day 1 preparation the conductivity of the test medium was 607 uS/cm, total hardness was 11° dH (=196 mg/L CaCOS) and alkalinity was 3° dH (= 50 mg/L CaCOS equivalent to 1 mL 0.1 N HCl).

Validity criteria fulfilled:

yes

Conclusions:

Based on nominal concentrations, the EC50 (24 hours) for Triflumuron was 13 µg a.s./L (95 %-confidence limits 6.1 to 70 µg a.s./L) and the EC50 (48 hours) was 1.6 µg a.s./L (95 %-confidence limits 0.63 to 3.3 µg a.s./L).

Executive summary:

There were no control immobilities which was well below the 10% value which is regarded to represent the limit for natural mortality. As the physico-chemical measurements show, the composition of the test water corresponds to the nominal values. The EC50 of the reference substance is located within the required range.

Thus, the study conditions and breeding quality meet the criteria. Measured concentrations of the test substance ranged from 88 to 130% for single sample determinations. As average concentrations for each test concentration ranged from 100 to 122% of nominal (total average 110%), nominal concentrations were used for calculations.

Based on nominal concentrations, the EC50 (24 hours) for Triflumuron was 13 µg/L and the EC50 (48 hours) was 1.6 µg/L. Neither immobility above 10% nor any occurrence of symptoms have been observed at concentrations up to 0.22 µg/L after 24 and 48 hours (NOEC). The lowest concentration showing mortality above 10% was 0.48 µg/L after 24 and 48 hours (LOEC). There was no concentration causing 100% immobility. Highest observed immobility was 83% at 25 µg/L (nominal water solubility of the test item) after 48 hours.

Description of key information

Based on nominal concentrations, the EC50 (24 hours) for Triflumuron was 13 µg/L and the EC50 (48 hours) was 1.6 µg/L. Neither immobility above 10% nor any occurrence of symptoms have been observed at concentrations up to 0.22 µg/L after 24 and 48 hours (NOEC). The lowest concentration showing mortality above 10% was 0.48 µg/L after 24 and 48 hours (LOEC). There was no concentration causing 100% immobility. Highest observed immobility was 83% at 25 µg/L (nominal water solubility of the test item) after 48 hours.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

1.6 µg/L