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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Results are reported based on nominal concentrations. Report indicates that test media samples were taken and supplied to the sponsor for confirmation. No major deficiencies were identified. The study was carried out according to GLP and using recognised guidelines. As such a reliability of 1 is deemed accurate.
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
yes
Remarks:
No analytical confirmation
GLP compliance:
yes
Specific details on test material used for the study:
Batch number 37777003
Analytical monitoring:
not specified
Details on sampling:
Samples of the stock solution and the highest test concentration at 0h and 48h were collected and stored in the freezer until analysed by the sponsor.
Vehicle:
no
Details on test solutions:
6000 mg of the test item was solved in 1000 mL reconstituted test water (dilution water) by magnetic stirring on the day of the test start. The test solutions were made by dilution of the stock solution (approx. 6000 mg/L). All test solutions were diluted in reconstituted test water. The nominal concentration of the test item in the test solutions were: 1000; 2000; 3000; 4000; 5000 and 6000 mg/L.
Test organisms (species):
Daphnia magna
Details on test organisms:
The method uses newly hatched animals, 6 to 24 hours old, which are incubated for 48 hours in a gradient of the test item. The animals were taken from Toxicon's continuous culture of Daphnia magna. The culture originates from DHI, Denmark and is on working days fed with approximately 50-75 mL green algae Pseudokirchneriella subcapitata. A qualification test on the Daphnia magna culture was made on the 15th of May 2008 to assure the quality of the test animals. EC50 was 1.3 mg/L, which confirmed that the culture was suitable as a test organism according to OECD TG no. 202.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
Not applicable
Hardness:
250 ± 25 mg/l (expressed as CaC03)
Test temperature:
21±1°C (nominally)Measured temperatures not reported
pH:
pH of 7.55 to 8.03
Dissolved oxygen:
99.4 to 102.6
Salinity:
Not applicable
Nominal and measured concentrations:
Nominal concentrations: 1000, 2000, 3000, 4000, 5000 and 6000 mg/L. Measured concentrations: Not confirmed
Details on test conditions:
Reconstituted test water, as specified in OECD TG 202, was used as dilution water. In the controls, only reconstituted test water was used. 6 000mg of the test item was dissolved in 1 000 mL reconstituted test water (dilution water) by magnetic stirring on the day of the test start. The test solutions were made by dilution of the stock solution (approx. 6 000 mg/L). All test solutions were diluted in reconstituted test water. The animals were incubated in glass Petri dishes (50 mL), with 25 mL solution. Four replicates, with five animals in each replicate, were used for both the test concentrations and for the control. The dishes were incubated in a thermo-constant room at a temperature of 21±1° C and subdued light with the light rhythm of 16 hours light: 8 hours darkness. Before the experiment start, pH and oxygen saturation was measured in all the solutions. The numbers of immobilised animals were observed at 24 and 48 hours in all the test dishes. At the end of the experiment pH and oxygen saturation were measured in all the test groups (4 pooled replicates/group).
Reference substance (positive control):
yes
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 6 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Remarks:
Graphical Interpolation
Effect conc.:
3 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC100
Effect conc.:
6 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
< 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
EC50
Remarks:
Probit analysis
Effect conc.:
2 466 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
The criteria for validity of the test according to OECD no. 202 were fulfilled: - In the controls, not more than 10% of the Daphnia sp. were immobilised or trapped at the surface of the water.- The dissolved oxygen concentrations were above 3 mg/L during the test. A slight difference in the determined EC50-value was found between the two methods used for calculation of the EC50-value (table 3). An EC50-value of 2466 mg/L was determined (by probit-analysis) for the 48 hours of exposure for the test item Cyclic Trimethylolpropane Formal. The toxicity increased during the time of exposure. Due to the fact that the immobilisation degree was the same as the control, even though the immobilisation degree was 25% at a lower concentration, the NOEC-value (24 h) was found to be 5 000 mg/L.
Results with reference substance (positive control):
The report refers to the conduct of a reference test: "A qualification test on the Daphnia magna culture was made on the 15th of May 2008 to assure the quality of the test animals. EC50was 1.3 mg/L, which confirmed that the culture was suitable as a test organism according to OECD TG no. 202." It is assumed that the reference material was potassium dichromate however, this has not been detailed in the report, it is therefore impossible to determine whether this EC50 is comparable to the expected toxicity for Daphnia magna.
Reported statistics and error estimates:
Statistics conducted using both Probit-analysis and graphic interpolation

Nominal Concentration (mg/L)

24 hours

% immobilised

48 hours

% immobilised

0 h

pH

48 h

pH

0 h

Dissolved

Oxygen

48 h

Dissolved

Oxygen

Control

0

10

7.97

8.02

102.1

100.0

1000

5

20

7.89

8.03

102.2

100.0

2000

0

20

7.82

8.03

102.3

99.5

3000

25

50

7.76

8.01

102.4

99.4

4000

5

90

7.70

8.00

102.0

99.4

5000

10

80

7.64

7.96

102.2

99.8

6000

45

100

7.55

7.97

102.6

99.8

Validity criteria fulfilled:
yes
Remarks:
1. In the controls, not more than 10% of the Daphnia sp. were immobilized or trapped at the surface of the water 2. The dissolved oxygen concentrations were above 3 mg/l during the test.
Conclusions:
The EC50 was determined to be 3000 mg/L and 2466 mg/L by graphical interpolation and probit analysis respectively. The NOEC was considered to be <1000 mg/L.OECD 202 validity criteria were achieved. However, the report is brief and lacks analytical confirmation of measured concentrations.
Executive summary:

A "Daphnia sp., Acute Immobilisation Test" was performed on the test item Cyclic Trimethylolpropane Formal by Toxicon AB, Harslov, Sweden, in June 2008 in accordance with the principles of good laboratory practice.

The nominal test concentration range included an untreated control group and six test groups at 1000, 2000, 3000, 4000, 5000 and 6000 mg/L. All test concentrations greatly exceed the maximum test concentration required by the test guideline (100 mg/L)

The test was conducted following OECD 202 test guideline Daphnia, Acute Immobilisation Test.

In general the report is minimal and limited details are reported however, the OECD 202 TG validity criteria were achieved. The EC50 was determined to be 3000 mg/L and 2466 mg/L by graphical interpolation and probit analysis respectively. The NOEC was considered to be less than the lowest test concentration (<1000 mg/L) and could not be determined accurately.

The report documents that samples were taken from the initial stock solution and highest test solution and supplied to the sponsor for confirmation. The results of analysis and an analytical method have not been provided. It is a requirement of the test guideline to measure test concentrations, as a minimum at the highest and lowest test concentrations, therefore as the study stands it is deficient.

To attempt to find convincing data to demonstrate that test concentrations were achieved the Hydrolysis report (W09 - 1383) was reviewed. This report stated that CTF was found to be hydrolytically stable for five days at pH 7 and 9, which encompasses the conditions for this algal study and therefore it may be possible to assume that test concentrations may have been acceptable during the fish test.

 

In addition the Biodegradation study (08 -290 -3) demonstrated little reduction of DOC in the first 7 days at 20 -25° C which indicates that limited degradation may have occurred during the fish test. Finally the water solubility for CTF stated on the SRC PHYSPROP database is reported to be > 217000 mg/L (217 g/L) and therefore it can be concluded that this fish test was conducted within the limit of water solubility.

Based on the nominal exposure concentrations the 48 hr EC50 has been calculated to be 2466 mg/L.

Description of key information

The key study provided indicated no risk to aquatic invertebrates as the derived EC50 was 2466 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Dose descriptor:
EC50
Effect concentration:
2 466 mg/L

Additional information

A single key study is provided which concluded that based on the nominal exposure concentrations the 48 hr EC50 for Daphnia exposed to 5-ethyl-1,3-dioxane-5-methanol was 2466 mg/L.