6-Amino-5-chloro-2-cyclopyrimidine-4-carboxylic acid

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:

31 Jul - 02 Aug 2007

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:

2004

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all test concentrations at 0 h and 48 h
- Sampling method: collected at mid-depth of vessel
- Sample storage conditions before analysis: processed immediately

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: the highest test concentration was prepared by mixing the required amount of test substance with dilution water. The test concentrations were prepared separately by dilution of the stock solution.
- Eluate: no
- Differential loading: no
- Controls: yes, test medium control
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation: < 24 h
- Method of breeding: same conditions as in test
- Source: bred at testing facility
- Feeding during test : no

ACCLIMATION
- Acclimation period: 21 d
- Acclimation conditions (same as test or not): breeding conditions same as in test
- Food type: mixture of yeast, cereal grass media and trout chow
- Frequency: daily
- Health during acclimation (any mortality observed): no mortality observed

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

136 mg/L as CaCO3

Test temperature:

19.0 - 20.3 °C

pH:

7.7 - 8.4

Dissolved oxygen:

8.4 - 8.8 mg/L

Nominal and measured concentrations:

Nominal test substance concentrations: 3.8, 7.5, 15, 30, 60 and 120 mg a.s./L
Mean meas. test substance concentrations: 3.7, 7.4, 15, 30, 59 and 120 mg a.s./L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL glass beakers
- Fill volume: 220 mL
- Headspace: 30 mL
- Aeration: no
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water located on the Wildlife International, Ltd. site, passed through sand filter and aerated. Prior to use filtered to 0.45 μm and passed through an ultraviolet sterilizer.
- Total organic carbon: <1 mg C/L
- Alkalinity:184 mg/L as CaCO3
- Conductivity: 310 μmhos/cm
- Intervals of water quality measurement: at 0, 24 and 48 h

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16:8 h day-nigh cycle
- Light intensity: Fluorescent light 198 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mobility after 5, 24 and 48 h

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

43 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 95% Fiducial Interval: 30 and 69 mg a.s./L

Details on results:

- Behavioural abnormalities: lethargy at test concentrations of 15 mg/L after 24 h
- Mortality of control: no
- Other adverse effects control: no
- Immobilisation of control: no
- Abnormal responses: no

Reported statistics and error estimates:

Probit analysis, the moving average method, and binomial probability with nonlinear interpolation using software of Stephan, C.E., U.S. EPA. 1978.

Table 1: Immobilisation and sublethal effects after 48 hours

Mean, Measured Concentration [mg a.s./L]	Cumulative number of immobilised/ total number of daphnids after 48 h	Observations
3.7	0/20	-
7.4	0/20	-
15	6/20	-
30	11/20	-
59	8/20	3 lethargic specimen
120	16/20	4 lethargic specimen
control	0/20	-

Table 2: Validity criteria for OECD 202.

Criterion from the guideline	Outcome	Validity criterion fulfilled
In the control, including the control containing the solubilising agent, not more than 10% of the daphnids should have been immobilized.	0%	yes
The dissolved oxygen concentration at the end of the test should be ≥ 3 mg/L in control and test vessels.	> 8 mg/L	yes

 

 

Validity criteria fulfilled:

yes

Remarks:

Please see Table 2 at "Any other information on results and tables" for more details

Description of key information

EC50 (48 h) = 43 mg/L (mean measured, OECD 202, Daphnia magna, immobility)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

43 mg/L

Additional information

One experimental study testing the acute toxicity of the test substance towards aquatic invertebrates is available.

This key freshwater study was performed according to GLP and OECD 202. Daphnia magna was exposed to concentrations ranging from 3.7 to 120 mg a.s./L (mean measured). Test substance concentrations were measured directly by high performance liquid chromatography (HPLC) with UV detection. Mean measured concentrations were between 99.2 to 101% of nominal concentrations.
The 48-hour EC50 value, based on mobility, was 43 mg a.s./L (mean measured, 95%-CI: 30 to 69 mg a.s./L).