Potassium 2-(4-chloro-2-methylphenoxy)propionate

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:

12.12.2006 - 14.12.2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Mecoprop

EC Number:

230-386-8

EC Name:

Mecoprop

Cas Number:

7085-19-0

Molecular formula:

C10H11ClO3

IUPAC Name:

2-(4-chloro-2-methylphenoxy)propanoic acid

impurity 1

Reference substance name:

Water

EC Number:

231-791-2

EC Name:

Water

Cas Number:

7732-18-5

Molecular formula:

H2O

IUPAC Name:

water

Test material form:

solid

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia Magna
Animals Daphnia Magna (Straus) used in the experiment were taken from own test laboratory culture. In the experiment animals in good physiological conditions, up to 24 hours old were used.

Daphnia Magna Culturing
The culture is maintained in 25 l aquariums at room temperature (20 to 22 oC) and natural photoperiod (daily light). The culture is maintained in standardized Elendt water M7. Pseudokirchneriella subcapitata algae suspension from own culture is used as a food for Daphnia. In addition to the algae suspension, Daphnia are fed with fresh yeast suspension or lyophilized Spirulina suspension as a source of vitamins of group B and microelements indispensable for proper growth of Daphnia population. Once a week Daphnia population is “depleted” to maintain bio-balance (too high concentration may lead to appearance of males and ephippia production, decline in physiological conditions and finally to population collapse). A day before the test set up, the mature animals were taken from culture to container of about 1 liter (with help of net with proper mesh size) Since Daphnia (cultured in proper way – i.e. without males and ephippia) reproduce partenogenetically young (less than 24 old) population of animals was obtained on the next day. These young Daphnia were used in tests.

Study design

Test type:

static

Water media type:

other: Elendt water M7

Limit test:

yes

Total exposure duration:

48 h

Test conditions

Test temperature:

20±1 oC

pH:

Information on pH is included in Table 1.

Dissolved oxygen:

Information on oxygene concentration is included in Table 1.

Nominal and measured concentrations:

Concentration
In the study test material was used in one concentration (limit test) – 100 mg/l. Concentration of test material was prepared by weighting of 10 mg of test material, precise mixing in 100 ml of Elendt water used in the test. And then, introducing to the system. Concentration of test material was determined by chemical analysis.

Details on test conditions:

The test environment and the dilution medium used for preparing the test material solution was standardized Elendt water M7, the same like used in culture. The test was run in plastic test container of 100 ml capacity. Before test start Elendt water was aerated for 30 minutes. Test concentrations as well as control was set up in four replicates. The volume of test material solution in every replicate was 25 ml. Five individuals of Daphnia Magna were used per each replicate. (i.e. 20 animals per concentration). Therefore there was 5 ml of test solution per each animal (according to OECD Guideline there should be at least 2 ml). The test was run for 48 hours in natural photoperiod. The test was run in static manner Animals were not fed during the test and the temperature was maintained in range 20±1 oC. At the beginning of test and after 48 h pH values and content of dissolved oxygen were measured, the same measurements were performed for fresh solutions. Information on pH and oxygene concentration is included in Table 1.

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Effect concentrations 2

Key result

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

>= 100 mg/L

Effect concentrations 3

Key result

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

> 100 mg/L

Effect concentrations 4

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Effect concentrations 5

Key result

Duration:

24 h

Dose descriptor:

EC0

Effect conc.:

>= 100 mg/L

Effect concentrations 6

Key result

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

> 100 mg/L

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

EC50 after 48 h >100 mg/l
EC0 after 48 h ≥ 100 mg/l
EC100 after 48 h > 100 mg/l

Executive summary:

Observation and assessment

Observation and the results (mortality and immobility) were scored after 24 and 48 hours of exposure. The results were recorded on results sheets. The animals were regarded as dead or immobile of they show no ability to swim within 15 seconds after delicate shaking of the test container.

Toxicity of tested material to Daphnia magna is assessed as EC₅₀ (median concentration causing immobilization i.e. inability to swim of 50% population after 24 and 48 hours of exposure, EC₀ (the highest concentration causing no immobilization) and EC₁₀₀(the lowest concentration causing 100% of immobilization). In case of no mortality was observed in test concentration the EC₅₀/48 h is above this concentration, EC₀ value is equal of above this concentration and EC₁₀₀ is above this concentration.

Results and dusscusion

Validity criteria

All validity criteria were met:

-         Mortality and immobilization of tested animals in control was 0% (criterion should not exceed 10%)

-         Concentration of dissolved oxygen was higher than 3 mg/l

Final Results

Median concentration causing 50% immobilization of Daphnia magna population (EC₅₀) after 48 hours was above 100 mg/l. EC₀after 48 hous was above or equal 100 mg/l and EC₁₀₀ after 48 hours was above 100 mg/l.