1,6-Naphthyridine-3-carboxylic acid, 4-(4-cyano-2-methoxyphenyl)-5-ethoxy-1,4-dihydro-2,8-dimethyl-

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:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

Sampling schedule
Control: at 48 hours
Test concentration/s: 1.56, 3.13, 6.25, 12.5, 25, 50 and 100 mg/L at 0 and 48 hours

Vehicle:

no

Remarks:

Auxiliaries used were an ultrasonic bath and a magnetic stirrer

Details on test solutions:

Pre-treatment of test item and preparation of test item concentrations
- a stock solution was prepared to give the desired series of test concentrations
- 100.5 mg of the test item were added to 1 litre of dilution water, treated for 1 h in an ultrasonic bath and stirred for 24 h on a magnetic stirrer
- undissolved particles of the test item were removed by filtration using a folded filter (pore size 7 - 12 μm)
- pH was measured to be 7.3
- to produce the different test item concentrations appropriate amounts of the stock solution were diluted with dilution water to a volume of 500 mL
- 50 mL of the prepared solutions were taken per replicate and 0.5 mL of dilution water was given to all replicates resulting in the final nominal concentrations

Test organisms (species):

Daphnia magna

Details on test organisms:

Name: Daphnia magna STRAUS, parthenogenetic females
Source: Strain of Bundesgesundheitsamt Berlin
Maintenance and Acclimatisation: A population of parthenogenetic females of synchronized age structure has been maintained for more than 20 years in the test facility under constant temperature conditions (20 +/- 2 °C) at a 16 : 8 hour light-dark photoperiod (light intensity: < 20 μE x m-2 x s-1). The culture water (so-called 'M4 medium') was partly renewed once a week. The Daphnia were exclusively fed unicellular green algae (Desmodesmus subspicatus) 'ad libitum'. Mortalities of parent Daphnia during the culture period were recorded daily. The neonates were separated from their parent Daphnia by filtration prior to the acute test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

14.9 °dH (= 266 mg/L CaCO3)

Test temperature:

19.9 - 20.7 °C

pH:

7.6 - 8.0

Dissolved oxygen:

8.6 - 8.9 mg/L

Nominal and measured concentrations:

nominal [mg/L] 1.56, 3.13, 6.25, 12.5, 25, 50 and 100
measured [mg/L]: < 3.01, < 3.01, < 3.01, 3.96, 7.65, 15.42, 27.30

Details on test conditions:

Exposure conditions
- Test vessels: 100 mL glass beakers covered with watch glasses holding 5 neonates in 50 mL of test medium
- Experimental design: 7 concentrations plus 1 control; 5 neonates per vessel, 4 replicates per concentration/control
- no feeding during the exposure period
- static system
- Method of initiation: neonates were placed in prepared media
- Photoperiod: 16 h light : 8 h dark
- Temperature of incubation unit: 19.2 to 19.4°C
- Aeration: none
- Test item concentration/s: 1.56, 3.13, 6.25, 12.5, 25, 50 and 100 mg/L (nominal)
- Method of administration: stock solution
- Medium renewal: none
- Duration of exposure: 48 hours
- Criteria of effects: the item-induced alteration of the normal mobility behaviour and the loss of locomotory actions of the neonates, observed at 24 and 48 hours

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

6.95 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat. (dissolved fraction)

Remarks:

DOC

Basis for effect:

mobility

Details on results:

The results are expressed in terms of arithmetic mean measured concentrations. The results refer to the test item concentrations calculated on base of the measured DOC values. According to the product information 1 mg/L DOC equals to 1.5 mg/L test item (molecular weight 379.4 g/mol, empirical formula C21H21N3O4).
The EC 50 was calculated by probit analysis using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10).

Validity criteria fulfilled:

yes

Remarks:

immobilisation and other abnormalities in the controls did not exceed 10 % by the end of the test; dissolved oxygen concentration remained above 3 mg/L throughout the exposure period

Conclusions:

After 48 hours of exposure an EC50 of 6.95 mg/L against Daphnia was determined for Carboxy-TH-naphthyridin.

Executive summary:

A study was conducted in accordance with the Council Regulation (EC) No 440/2008, Method C.2 ‘Acute toxicity for Daphnia’ (2008) which is equivalent to OECD Guideline for Testing of Chemicals No. 202 'Daphnia sp., Acute Immobilisation Test' (adopted April 13, 2004). The study was performed to assess the acute toxicity of Carboxy-TH-naphthyridin to Daphnia magna STRAUS under static conditions. The Daphnia were exposed to a range of concentrations, nominally 1.56, 3.13, 6.25, 12.5, 25, 50 and 100 mg/L of Carboxy-TH-naphthyridin dissolved in dilution water. Auxiliaries used to prepare the test media were an ultrasonic bath, a magnetic stirrer and a folded filter. On sponsors request the content of the test item during the exposure period was checked using DOC determination.

Observations were made on the swimming ability and the immobilisation rate, respectively, after 24 and 48 hours of exposure. After 48 hours of exposure an EC50 of 6.95 mg/L was determined.

The results are expressed in terms of arithmetic mean measured concentrations. The results refer to the test item concentrations calculated on base of the measured DOC values. According to the product information 1 mg/L DOC equals to 1.5 mg/L test item (molecular weight 379.4 g/mol, empirical formula C21H21N3O4). The EC50 was calculated by probit analysis using the statistics programme ToxRatPro Version 2.10 (released 2010-09-10).

Description of key information

After 48 hours of exposure an EC50 of 6.95 mg/L against Daphnia was determined for Carboxy-TH-naphthyridin.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

6.95 mg/L