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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
[Further information is included as attachment to Iuclid section 13]

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across approach is based on the hypothesis that the source and target substances have similar physico-chemical, toxicological, ecotoxicological and environmental fate properties because of their structural similarity.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
The target and the source substances (Table 1) are 1,2-branched pentyl cyclopentane. The source substance is an alcool, while the target substance is a ketone. The source substance is the secondary alcohol formed by metabolism of the Target substance.

3. ANALOGUE APPROACH JUSTIFICATION
Based on the close structural similarity, on the similar basic physico-chemical properties and the same environmental profile, both target and source substances are not expected to have significantly difference on the aquatic toxicity.
The study performed on the source substance (OECD 202, GLP) is adequate and reliable for the purpose of the prediction based on read-across. The test material used represents the source substance as described in the hypothesis in terms of purity and impurities. The results of the studies are adequate for the purpose of classification and labelling.
Therefore, based on the considerations above, it can be concluded that the results of the Short term toxicity to daphnia study conducted with the source substance are likely to predict the properties of the target substance and are considered as adequate to fulfil the information requirement.

4. DATA MATRIX
See Iuclid section 13
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: the 48h-EC50 value was determined as a geometric mean value of the two consecutive test concentrations with 0 and 100% immobilisation (95% confidence interval: 10 -32 mg/L).
Duration:
48 h
Dose descriptor:
other: The highest tested concentration without observed effect
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
See table 6.1.3/2 in "Any other information on results incl. tables".

During the first 24 hours of the test, no immobilized test organisms were determined in the control and up to and including the test item concentration of 10 mg/L. At the next higher concentration of 32 mg/L, the immobilization was 75%. At the highest test concentration of 100 mg/L, all test organisms were found to be immobile after 24 hours.
After 48 hours of exposure, no immobilized test organisms were determined in the control and up to and including the test item concentration of 10 mg/L. From the concentration of 32 mg/L onwards all daphnids were found to be immobile.

No remarkable observations were made concerning the appearance of the test media. All test media were clear throughout the entire test duration.
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- The result of the latest positive control test in March 2008 (48h-EC50 = 0.73 mg/L, RCC Study No. B83744) indicated that the sensitivity of the test organisms was within the historical range of Harlan Laboratories (48h-EC50 from 1996 to 2008 = 0.53-1.1 mg/L).
Reported statistics and error estimates:
None

Table 6.1.3/1: Results obtained for the concentrations of the treatment samples

Age (day)

Nominal concentration of test item (mg/L)

Measured concentration of test item

Sample preparation factor

Determined average concentration of test item (mg/L)

Recovery rate (%)

Sample 1

Sample 2

average

0

Control

0.32

1.0

3.2

10

32

100

<LOQana

0.403

1.40

3.92

11.7

28.4

95.2

<LOQana

0.384

1.41

4.45

9.86

36.1

92.6

n.a.

0.393

1.41

4.18

10.8

32.3

93.9

1.01

1.01

1.01

1.01

1.01

1.01

1.01

n.a.

0.397

1.42

4.22

10.9

32.6

94.9

n.a.

124

142

132

109

102

95

2

Control

0.32

1.0

3.2

10

32

100

<LOQana

0.332

1.28

3.54

8.59

31.3

98.9

<LOQana

0.361

1.25

3.75

9.77

30.6

103

n.a.

0.346

1.26

3.65

9.18

31.0

101

1.01

1.01

1.01

1.01

1.01

1.01

1.01

n.a.

0.35

1.28

3.68

9.27

31.3

102

n.a.

109

128

115

93

98

102

LOQana = 0.104 mg test item/L

n.a. = not applicable

Table 6.1.3/2: Effect of the test substance on the mobility of Daphnia magna

Nominal test item concentration (mg/L)

No. of daphnids tested

Immobilized daphnids after 24 hours

Immobilized daphnids after 48 hours

No.

%

No.

%

Control

0.32

1.0

3.2

10

32

100

20

20

20

20

20

20

20

0

0

0

0

0

15

20

0

0

0

0

0

75

100

0

0

0

0

0

20

20

0

0

0

0

0

100

100

Validity criteria fulfilled:
yes
Conclusions:
Based on data available on the source substance, the 48h-EC50 was determined at 18 mg/L (95% confidence interval: 10 -32 mg/L).
Executive summary:

The acute toxicity of the target substance to Daphnia magna was determined using an experimental study performed on a source substance in a 48h static test according to the EU Method C.2 and the OECD Guideline 202 with GLP statement.


The nominal test item concentrations tested were 0.32, 1.0, 3.2, 10, 32 and 100 mg/L. Additionally, a control group was tested in parallel. Since the test item was determined to be volatile, the test was performed in 50 mL glass tubes completely filled with about 50 mL of test medium. The test tubes were made tight with glass stoppers to avoid losses of the volatile substance.


At the start and end of the test, the analytically determined concentrations of the test item in the test media were between 93 and 142% of the nominal values. Thus, the correct dosing of the test item was confirmed. Furthermore, it has been demonstrated that the test item was stable during the test period of 48 hours under the conditions of the test, and the reported biological results are based on the nominal concentrations of the test item.


All validity criteria were fulfilled but the separation factor between concentrations greatly exceeded the guideline recommendation and no effect and 100% effect concentrations were adjacent. The 48h-EC50 value was determined as a geometric mean value of the two consecutive test concentrations with 0 and 100% inhibition of mobility, at 18 mg/L (95% confidence interval: 10 -32 mg/L).

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 12 August to 03 September 2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study was performed according to the EU Method C.2 and the OECD Guideline 202 with GLP statement. All validity criteria were fulfilled but the separation factor between concentrations greatly exceeded the guideline recommendation and no effect and 100% effect concentrations were adjacent. The 48h-EC50 value was determined as a geometric mean value of the two consecutive test concentrations with 0 and 100% inhibition of mobility. In addition, validation applies with restrictions as the test substance is not the registered substance. Read-across is justified as data relates to a chemical substance structurally similar to the registered substance.
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Deviations:
no
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes (incl. QA statement)
Remarks:
Swiss GLP compliance inspected on 05-09 and 26-30 November 2007 / signed on 12 November 2008
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
None
Analytical monitoring:
yes
Details on sampling:
Quadruplicate samples were taken from each treatment before the start of the test and at the end of the test after 48 hours.
For the 48-hour stability samples, the contents of the respective replicates were combined prior to sampling.
The concentrations of the test item were analysed in duplicate test media samples of all test concentrations from both sampling times. From the control samples only one sample was analysed from the corresponding sampling times.
The samples (2 mL) were directly pipetted into headspace vials containing 0.6 g sodium chloride and further 20 µL acetone were added (giving a dilution factor of 1.01). Subsequently, the samples were analysed by Headspace-GC/FID without further storage.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test medium of the highest nominal concentration of 100 mg/L was prepared in a completely filled and tightly closed stirring vessel by dissolving 100.6 mg of test item in 1000 mL of test water using intense stirring for 10 minutes at room temperature. Adequate volumes of this test medium were diluted with test water to prepare the test media with the lower test item concentrations. The test media were prepared just before introduction of the daphnids.
- Controls: one control without test substance.
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): not applicable
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain: clone 5
- Source: University of Sheffield / UK
- Age at study initiation (mean and range, SD): 6-24 hours old
- Weight at study initiation (mean and range, SD): no data
- Length at study initiation (length definition, mean, range and SD): no data
- Valve height at study initiation, for shell deposition study (mean and range, SD): no data
- Peripheral shell growth removed prior to test initiation: no data
- Method of breeding: The clone has been bred at Harlan Laboratories in reconstituted water of the quality identical to the water quality used in the tests and under temperature and light conditions identical to those of the tests.
- Feeding during test: no
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Remarks on exposure duration:
none
Post exposure observation period:
None
Hardness:
250 mg/L as CaCO3.
Test temperature:
20°C during the test.
pH:
7.9-8.0 during the test.
Dissolved oxygen:
8.1-8.9 mg/L during the test.
Salinity:
Not applicable
Nominal and measured concentrations:
- Nominal concentrations: 0.32, 1.0, 3.2, 10, 32 and 100 mg/L.
- Measured concentrations: See table 6.1.3/1 in "Any other information on results incl. tables".
At the start and end of the test, the analytically determined concentrations of the test item in the test media were between 93 and 142% of the nominal values. Thus, the correct dosing of the test item was confirmed. Furthermore, it has been demonstrated that the test item was stable during the test period of 48 hours under the conditions of the test, and the reported biological results are based on the nominal concentrations of the test item.
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 mL glass tubes
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: glass tubes completely filled with about 50 mL of test medium. The test tubes were made tight with glass stoppers to avoid losses of the volatile substance.
- Aeration: not aerated during the test period.
- Type of flow-through (e.g. peristaltic or proportional diluter): not applicable
- Renewal rate of test solution (frequency/flow rate): not applicable
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): not applicable
- Biomass loading rate: the volume of test solution for each daphnia was 10 mL

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted test water according to ISO 6341 was used in the study.
- CaCl2 x 2 H2O: 294 mg/L
- MgSO4 x 7 H2O: 123 mg/L
- NaHCO3: 65 mg/L
- KCl: 5.8 mg/L
- Alkalinity: 0.8 mmol/L
- The ratio of Ca:Mg and Na:K was 4:1 and 10:1 respectively, based on molarity.
- The test water was aerated prior to the start of the study until oxygen saturation was reached.
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16h light / 8h dark cycle with 30 min transition period.
- Light intensity: approx. between 500 and 630 Lux.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : immobilisation of the daphnids.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study: Yes
- Results used to determine the conditions for the definitive study: The enlarged spacing factor of 3.2 between the test concentrations was chosen because according to the results if the range-finding test the concentration-effect relationship was rather flat and thus a large concentration range had to be tested.
- Test concentrations: 0.32, 1.0, 3.2, 10, 32 and 100 mg/L.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: the 48h-EC50 value was determined as a geometric mean value of the two consecutive test concentrations with 0 and 100% immobilisation (95% confidence interval: 10 -32 mg/L).
Duration:
48 h
Dose descriptor:
other: The highest tested concentration without observed effect
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
See table 6.1.3/2 in "Any other information on results incl. tables".

During the first 24 hours of the test, no immobilized test organisms were determined in the control and up to and including the test item concentration of 10 mg/L. At the next higher concentration of 32 mg/L, the immobilization was 75%. At the highest test concentration of 100 mg/L, all test organisms were found to be immobile after 24 hours.
After 48 hours of exposure, no immobilized test organisms were determined in the control and up to and including the test item concentration of 10 mg/L. From the concentration of 32 mg/L onwards all daphnids were found to be immobile.

No remarkable observations were made concerning the appearance of the test media. All test media were clear throughout the entire test duration.
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- The result of the latest positive control test in March 2008 (48h-EC50 = 0.73 mg/L, RCC Study No. B83744) indicated that the sensitivity of the test organisms was within the historical range of Harlan Laboratories (48h-EC50 from 1996 to 2008 = 0.53-1.1 mg/L).
Reported statistics and error estimates:
None

Table 6.1.3/1: Results obtained for the concentrations of the treatment samples

Age (day)

Nominal concentration of test item (mg/L)

Measured concentration of test item

Sample preparation factor

Determined average concentration of test item (mg/L)

Recovery rate (%)

Sample 1

Sample 2

average

0

Control

0.32

1.0

3.2

10

32

100

<LOQana

0.403

1.40

3.92

11.7

28.4

95.2

<LOQana

0.384

1.41

4.45

9.86

36.1

92.6

n.a.

0.393

1.41

4.18

10.8

32.3

93.9

1.01

1.01

1.01

1.01

1.01

1.01

1.01

n.a.

0.397

1.42

4.22

10.9

32.6

94.9

n.a.

124

142

132

109

102

95

2

Control

0.32

1.0

3.2

10

32

100

<LOQana

0.332

1.28

3.54

8.59

31.3

98.9

<LOQana

0.361

1.25

3.75

9.77

30.6

103

n.a.

0.346

1.26

3.65

9.18

31.0

101

1.01

1.01

1.01

1.01

1.01

1.01

1.01

n.a.

0.35

1.28

3.68

9.27

31.3

102

n.a.

109

128

115

93

98

102

LOQana = 0.104 mg test item/L

n.a. = not applicable

Table 6.1.3/2: Effect of the test substance on the mobility of Daphnia magna

Nominal test item concentration (mg/L)

No. of daphnids tested

Immobilized daphnids after 24 hours

Immobilized daphnids after 48 hours

No.

%

No.

%

Control

0.32

1.0

3.2

10

32

100

20

20

20

20

20

20

20

0

0

0

0

0

15

20

0

0

0

0

0

75

100

0

0

0

0

0

20

20

0

0

0

0

0

100

100

Validity criteria fulfilled:
yes
Conclusions:
The 48h-EC50 was determined at 18 mg/L (95% confidence interval: 10 -32 mg/L).
Executive summary:

The acute toxicity of the test item to Daphnia magna was determined in a 48h static test according to the EU Method C.2 and the OECD Guideline 202 with GLP statement.

The nominal test item concentrations tested were 0.32, 1.0, 3.2, 10, 32 and 100 mg/L. Additionally, a control group was tested in parallel. Since the test item was determined to be volatile, the test was performed in 50 mL glass tubes completely filled with about 50 mL of test medium. The test tubes were made tight with glass stoppers to avoid losses of the volatile substance.

At the start and end of the test, the analytically determined concentrations of the test item in the test media were between 93 and 142% of the nominal values. Thus, the correct dosing of the test item was confirmed. Furthermore, it has been demonstrated that the test item was stable during the test period of 48 hours under the conditions of the test, and the reported biological results are based on the nominal concentrations of the test item.

All validity criteria were fulfilled but the separation factor between concentrations greatly exceeded the guideline recommendation and no effect and 100% effect concentrations were adjacent. The 48h-EC50 value was determined as a geometric mean value of the two consecutive test concentrations with 0 and 100% inhibition of mobility, at 18 mg/L (95% confidence interval: 10 -32 mg/L).

Description of key information

Read-across, EU Method C.2, OECD Guideline 202, GLP, key study, validity 2:
48h-EC50 = 18 mg/L (95% CI: 10-32 mg/L).

Key value for chemical safety assessment

Fresh water invertebrates

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

Additional information

To assess the short-term toxicity of the registered substance, 2 -pentylcyclopentan-1-one, to aquatic invertebrates, one valid experimental study is available.

 

This GLP study, assessed as a key study, was performed on a read-across substance, 2 -pentylcyclopentan-1-ol, according to EU Method C.2 and OECD Guideline 202. Both compounds (the registered substance and the read-across substance) acting with a non-polar narcotic MOA (Class 1) and are structurally related, in that each has an alkyl chain with five carbon (pentyl) with a cyclopentane ring. Both compounds contain a 2 -pentylcyclopentane skeleton. The cyclopentane ring is associated with a ketone functional group for the registered substance and with an alcohol functional group for the read-across substance.

In this study, Daphnia magna were exposed to the test substance (nominal concentrations: 0.32, 1.0, 3.2, 10, 32 and 100 mg/L) in a static condition during 48 hours. Additionally, a control group was tested in parallel. Since the test substance was determined to be volatile, the test was performed in 50 mL glass tubes completely filled with about 50 mL of test medium. The test tubes were made tight with glass stoppers to avoid losses of the volatile substance. At the start and end of the test, the analytically determined concentrations of the test substance in the test media were between 93 and 142% of the nominal values. Thus, the correct dosing of the test substance was confirmed. Furthermore, it has been demonstrated that the test substance was stable during the test period of 48 hours under the conditions of the test, and the reported biological results are based on the nominal concentrations of the test substance. All validity criteria were fulfilled but the separation factor between concentrations greatly exceeded the guideline recommendation and no effect and 100% effect concentrations were adjacent. The 48h-EC50 value was determined as a geometric mean value of the two consecutive test concentrations with 0 and 100% inhibition of mobility, at 18 mg/L (95% confidence interval: 10 -32 mg/L).

This supporting substance is considered adequate for read-across purposes based on structural similarity, on similar basic physico-chemical properties and similar environmental profile, as well as the same mode of action, between the registered substance and the analogue material used. In addition, as the log Kow value of the analogue material is slightly greater than the registered substance, the read-across approach is considered as a worst case scenario (see IUCLID section 13 for justification).