Benzeneacetic acid, 2-(6-carboxy-2,3-dimethylphenoxy)-

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27-nov-2008 to 29-nov-2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

ISO 6341 (Water quality - Determination of the Inhibition of the Mobility of Daphnia magna Straus (Cladocera, Crustacea))

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-[2-(carboxymethyl)phenoxy]-3,4-dimethylbenzoic acid

EC Number:

601-485-7

Cas Number:

117570-93-1

Molecular formula:

C17 H16 O5

IUPAC Name:

2-[2-(carboxymethyl)phenoxy]-3,4-dimethylbenzoic acid

Details on test material:

- Name of test material (as cited in study report): ASA404 C7
- Substance type: Off white powder
- Physical state: Solid
- Analytical purity: 99.9%
- Lot/batch No.: 072301
- Expiration date of the lot/batch: 18 March 2009
- Stability under test conditions: Stable
- Storage condition of test material: At room temperature in the dark

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all test concentrations and control
- Sampling method: Volume, 2 ml from the approximate centre of the test vessels at t=0 and t=48 h
- Sample storage conditions before analysis: Samples were stored in a freezer until analysis

Test solutions

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Preparation of test solutions started with a loading rate of 100 mg/l applying a 10-minute treatment period with ultrasonic waves followed by 74 hours of magnetic stirring to accelerate the dissolving of the test substance in the test medium. Obtained solutions contained undissolved material dispersed through and floating on the surface. The dispersion was consequently filtered through a 0.45 µm membrane filter (Whatman, RC55) to remove the non-dissolved material. The lower test concentrations were prepared by subsequent dilutions of the flitrate in test medium. The final test solutions were all clear and colourless.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Source: In-house laboratory culture
- Age at study initiation (mean and range, SD): <24 hours
- Method of breeding: Start of each batch, With newborn daphnids, i.e. less than 3 days old, by placing about 250 of them into 5 litres of medium in an all-glass culture vessel.
- Feeding during test: No

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

180 mg/l expressed as CaCO3

Test temperature:

19.6 - 20.8 °C

pH:

At t=0: 6.3 - 7.9
At t=48: 7.1 - 8.0

Dissolved oxygen:

At t=0: 8.9 - 9.4
At t=48: 8.9

Nominal and measured concentrations:

Nominal concentrations: 0.1, 1, 10 and 100 mg/l
Measured concentrations:
At t=0: 96.5% of nominal
At t=48: 98% of initial

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml, all-glass
- Type (delete if not applicable): open - Material, size, headspace, fill volume: glass, ~80ml, normal headspace
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4 for the highest test concentration, 2 in the lower test concentrations
- No. of vessels per control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source preparation of dilution water: Adjusted ISO medium
- Culture medium different from test medium: yes for culturing M7 medium is used

OTHER TEST CONDITIONS
- Adjustment of pH: 7.7 ± 0.3
- Photoperiod: 16 hours photoperiod daily

EFFECT PARAMETERS: EC50 daily

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10

Reference substance (positive control):

yes

Remarks:

potassium dichromate (K2Cr2O7)

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities: no
- Mortality of control: no
- Other adverse effects control: not observed

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- EC50/LC50:
The 24h-EC50 was 0.57 mg/l with a 95% confidence interval between 0.52 and 0.66 mg/l.

The 48h-EC50 was 0.35 mg/l with a 95% confidence interval between 0.31 and 0.40 mg/l.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

ASA404 C7 did not induce acute immobilisation of Daphnia magna at or below 10 mg/l after 48 hours of exposure (NOEC). A total of 40% immobile daphnia were observed at the highest test concentration of 100 mg/l.

Therefore, it is concluded that this study is valid and the 48h-EC50 exceeded 100 mg/l based on analytically confirmed nominal concentrations.