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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
22 February - 24 February 2001
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Test concentrations were analysed only at the start of the test, based on DOC. The concentrations were expected to be stable. Read across substance. Reliability 2
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
1984
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
(EEC Directive 92/69/EEC Method C.2; 1992)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Analytical monitoring:
yes
Details on sampling:
The test concentrations were analytically verified via DOC analysis according to DIN 38409 part 3. At the beginning of the test water parameters (pH value, oxygen concentration) were measured in one additiona l replicate per concentration and control groups. After 48 h the water parameters in the old media were measured in all replicates per concentration and control.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
Two preliminary range finding tests were conducted under static conditions. Based on the results of the preliminary tests a definitve test was performed with 5 concentrations of the stock solution: 31.3, 62.5, 125, 250 and 500 mg/L. The dilution factor was 2 and enabled the determination of 0 and 100% immobilisation after 24 and 48 hours. Prior the test item underwent dispersion treatment using a magnetic stirrer for 24 hours.The test item solutions were clearly dissolved after filtration of the stock solution in all tested concentrations levels throughout exposure.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna (Straus 1820)
- Strain/clone: Clone 5
- Source: in-house laboratory culture with a known history
- Age at study initiation: young daphnids with an age of < 24 hours
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
Dilution water: 264 CaCO3 mg/L
Test temperature:
21 ± 1 °C
pH:
Test start: 7.71 - 8.07
Test end: 7.75 - 8.02
Dissolved oxygen:
Test start: 8.36 - 9.0 mg O2/L
Test end: 8.39 - 8.85 mg O2/L
Conductivity:
Dilution water: 650 μS/cm
Nominal and measured concentrations:
Based on the results of 2 preliminary range-finding tests the following dilutions of the saturated solution were assigned to the final test: 31.3, 62.5, 125, 250 and 500 mg/L.
Details on test conditions:
TEST SYSTEM
The tests were performed in glass beakers (5 cm ID x 8 cm H), 50 mL

* 2 Range-finding tests (static):
- First range finding test: three test concentrations (1.0, 10 and 100 mg/L, NON-GLP-state). For the stock solution 100 mg/L was weighed out. The test solution was stirred 24 hours and filtered before use.
- Second range finding test: three test concentrations (250, 500 and 1000 mg/L, NON-GLP-state). For the stock solution 1000 mg/L was weighed out. Thes test solution was stirred 24 hours and filtered before use.

* Final test (static):
- Six test concentrations (1.0, 1.8, 3.2, 5.6 and 10% of SS (saturated solution) prepared at 50 mg/L plus one control each in 4-fold with 5 animals/test vessel (i.e. 20 animals/concentration).
- Loading rate: 12 mL test solution per organism
- Test vessels were maintained at 20 °C under a photoperiod of 16 hours light : 8 hours dark and without supplementary aeration or feeding during the 48 hour exposure period.
- The temperature was measured continuously and the pH and dissolved oxygen levels were recorded in each test vessel at the start and at the end of the study.
- Control: Dilution water without test item was tested under the same conditions as the test groups

OTHER TEST CONDITIONS
- Adjustment of pH: no
Reference substance (positive control):
yes
Remarks:
potassium dichromate (February 2001)
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
309 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL 292-327 mg/L
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
177 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL 170-184 mg/L
Details on results:
* Range-finding tests:
After 48 h of exposure in the first range finding test no biologically significant effect (≤ 10%) was seen at the nominal concentration of 100 mg/L. Therefore a second range finding test was carried out with a stock solution of 1000 mg/L. A total rate of immobilisation of daphnia was 100% at the nominal concentration of 500 mg/L. Based on these results, it was decided to perform the final test under static conditions
with concentrations ranging from 31.3 to 500 mg/L.

* Final test:
The EC10 and EC50 values were calculated by probit analysis in the tested concentration range. The EC10 after 48h was 157 mg/L. The EC50 after 48h was 177 mg/L.
Analytical confirmation of nominal concentrations was shown via DOC analysis. Recovery rates were 99-102 % of nominals.
Individual pH, temperature and dissolved oxygen values remained within acceptable limits throughout the duration of the study.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- 48-h EC50: 2.4 mg/L

Immobilisation Rates of the first Range finding test [%] (n=20)

Nominal concentration* [mg/L]

24 h

48 h

1. Repl.

   2. Repl.

MV

1. Repl.

2. Repl.

MV

100

0

0

0

0

0

0

10

0

0

0

0

0

0

1

0

0

0

0

0

0

Control

0

0

0

0

0

0

Repl. = replicate

MV = mean value

* stock solution 100 mg/L, filtrated

Immobilisation Rates of the second Range finding test [%] (n=20)

Nominal concentration* [mg/L]

24 h

48 h

1. Repl.

   2. Repl.

MV

1. Repl.

2. Repl.

MV

1000

100

100

100

100

100

100

500

100

100

100

100

100

100

250

30

20

25

80

70

75

Control

0

0

0

0

0

0

Repl. = replicate

MV = mean value

* stock solution 1000 mg/L, filtrated

Percentage of Daphnids Incapable of Swimming after 24 and 48 h of exposure (n=20)

Nominal concentration* [mg/L]

Immobilisation

24 h

48 h

Replicates

Replicates

1.

2.

3.

4.

MV

1.

2.

3.

4.

MV

500

100

100

100

100

100

100

100

100

100

100

250

0

20

0

0

5

100

100

100

100

100

125

0

0

0

0

0

0

0

0

0

0

62.5

0

0

0

0

0

0

0

0

0

0

31.3

0

0

0

0

0

0

0

0

0

0

Control

0

0

0

0

0

0

0

0

0

0

MV = mean value

Validity criteria fulfilled:
yes
Remarks:
No immobilization in control group, O2 conc. at end is >=3 mg/L in control and test vessels
Conclusions:
For dimethyl benzyl carbinol the 48 h EC50 (immobilisation) value for Daphnia magna is 177 mg/L.
Executive summary:

An acute Daphnia study was performed with dimethyl benzyl carbinol in accordance with OECD Guideline for Testing of Chemicals No. 202 under static conditions. Groups of twenty daphnids (less than 24 hours old) were exposed for 48 hours to five concentrations of the substance dispersed in test water (31.3 - 500 mg/L) and an untreated control. The initial concentrations were 31.3, 62.5, 125, 250 and 500 mg/L. The test item dilutions were clearly dissolved after filtration of the saturated solutions in all tested concentration levels throughout exposure. The EC50 -values at 24h and at 48 the were 309 and 177 mg/L, respectively.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The information is derived from read across
Justification for type of information:
Executive summary:
The acute Daphnia of Peomosa is assessed by using read across from Dimethyl benzyl carbinol (100-87-6) resulting in a 48- EC50 for Daphnia of 177 mg/l. Full details are presented in the attached file in the study record. Structural similarities and differences: The target and the source chemicals have a phenylethanol backbone and an alcohol functional group. The difference is that an additional methyl is present on the phenyl ring of Peomosa, and while Peomosa is a primary alcohol, Dimethyl benzyl carbinol is a tertiary alcohol. Overall, Dimethyl benzyl carbinol has one more carbon than Peomosa, resulting in a slightly higher log Kow. Bioavailability: The source chemical and the target chemical have similar bioavailability based on the similarity in chemical structure and physico-chemical properties. The molecular weight of the target substance (Peomosa) is 136, whereas for the source (Dimethyl benzyl carbinol) it is 150. They are both liquids. They have similar vapour pressures, 1.9 and 3.94 Pa. It can be seen that the water solubility of the target, 12339 mg/L, is somewhat higher and the log Kow (2.1) somewhat lower compared to the source (2029 mg/L and 2.44, respectively), which can be expected based on the additional methyl present in Dimethyl benzyl carbinol.
Mode of Action and the prediction of the aquatic toxicity information: The target and source (Peomosa and Dimethyl benzyl carbinol) are expected to have the same neutral organic mode of action, based on their similar carbon chain and their similar functional group, an alcohol. Peomosa is a neutral organic and its ecotoxicity then is driven by log Kow: a substance with a higher log Kow will be more toxic. Uncertainty of the prediction: There are no remaining uncertainties. The prediction is conservative, as Peomosa has a lower log Kow than the analogue Dimethyl benzyl carbinol and therefore considered slightly less toxic. Correction based on molecular weight is not performed, as the difference in MW is small and the prediction is conservative for Peomosa and not critical for hazard assessment.
Reason / purpose:
read-across source
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
177 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% CL 170 - 184 mg/L

Description of key information

Peomosa has an 48h EC50 for Daphnids of 177 mg/L based on the result of an acute Daphnia test of the analogue Dimethyl benzyl carbinol.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
177 mg/L

Additional information

The short-term toxicity to aquatic invertebrates is based on read across from Dimethyl benzyl carbinol. First the study with the analogue is described and thereafter the read across justification is presented.

Short-term toxicity to aquatic invertebrates with Dimethyl benzyl carbinol:

An acute Daphnia study was performed with Dimethyl benzyl carbinol in accordance with OECD Guideline for Testing of Chemicals No. 202 under static conditions. Groups of twenty Daphnids (less than 24 hours old) were exposed for 48 hours to five concentrations of the substance dispersed in test water (31.3 - 500 mg/L) and an untreated control. The initial measured concentrations were 31.3, 62.5, 125, 250 and 500 mg/L. The substance was not measured at the end of the exposure period. In view of the high water solubility and low vapour pressure the initial measured concentrations are expected to be maintained during the study. The EC50- values at 24h and at 48h were 309 and 177 mg/L, respectively.

Peomosa and its 48-h Daphnia toxicity using read across information from Dimethyl benzyl carbinol

Introduction and hypothesis for the analogue approach

The substance Peomosa is a primary alcohol. For this substance no experimental Daphnia toxicity data are available. In accordance with Article 13 of REACH,lacking information can be generated by means of applying alternative methods such asin vitrotests, QSARs, grouping and read-across. For assessing the Daphnia toxicity of Peomosa the analogue approach is selected because for one closely related analogue reliable acute Daphniatoxicitydata are available.

Hypothesis: Peomosa has a similar acute Daphniatoxicity as Dimethyl benzyl carbinolbased on the similarity in structure and the neutral organic

Available experimental information: The source chemical was tested in a well performed short term Daphnia toxicity test according to the guideline OECD TG 202 in a static test set up design, indicated with a Klimisch 2 rating for reliabilitybecause test substance was measured as DOC. The 48h EC50 value was 177 mg/L. 

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical are shown in the data matrix. Also physico-chemical properties thought relevant for aquatic toxicity are listed in there. Physico-chemical properties of source and target chemicals are very similar. 

Purity / Impurities

The purity and impurities of the target chemical do not indicate other aquatic toxic potential and/or the acute/chronic ratio. The impurities are all below < 10%.

Analogue approach justification

According to Annex XI 1.5 read across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation.

Structural similarities and differences: The target and the source chemicals have a phenylethanol backbone and an alcohol functional group. The difference is that an additional methyl is present on the phenyl ring of Peomosa, and while Peomosa is a primary alcohol, Dimethyl benzyl carbinol is a tertiary alcohol. Overall, Dimethyl benzyl carbinol has one more carbon than Peomosa, resulting in a slightly higher log Kow.

Bioavailability:The source chemical and the target chemical have similar bioavailability based on the similarity in chemical structure and physico-chemical properties. The molecular weight of the target substance (Peomosa) is 136, whereas for the source (Dimethyl benzyl carbinol) it is 150. They are both liquids. They have similar vapour pressures, 1.9 and 3.94 Pa. It can be seen that the water solubility of the target, 12339 mg/L, is somewhat higher and the log Kow (2.1) somewhat lower compared to the source (2029 mg/L and 2.44, respectively), which can be expected based on the additional methyl present in Dimethyl benzyl carbinol.

Mode of Action and the prediction of the aquatic toxicity information: The target and source (Peomosa and Dimethyl benzyl carbinol) are expected to have the same neutral organic mode of action, based on their similar carbon chain and their similar functional group, an alcohol. Peomosa is a neutral organic and its ecotoxicity then is driven by log Kow: a substance with a higher log Kow will be more toxic.

Uncertainty of the prediction: There are no remaining uncertainties. The prediction is conservative, as Peomosa has a lower log Kow than the analogue Dimethyl benzyl carbinoland therefore considered slightly less toxic.Therefore, in the ECHA guidance (RAAF, 2015) terminology it receives a score of 5 (acceptable with high confidence), because the rationale for the selection of the analogues is clearly documented and there is supporting evidence provided. Correction based on molecular weight is not performed, as the difference in MW is small and the prediction is conservative for Peomosa and not critical for hazard assessment. 

Data matrix

The relevant information on physico-chemical properties and ecotoxicological characteristics for the source and target substances are presented in the data matrix below.

Conclusions on this endpoint

When using read across the result derived should be applicable for C&L and/or risk assessment and be presented with adequate and reliable documentation.For Peomosa the aquatic toxicity can be predicted using Dimethyl benzyl carbinol as an analogue based on similarity in structure and the communal neutral organic Mode of Action. The EC50 of Dimethyl benzyl carbinol of 177 mg/l can be used for Peomosa.

Final conclusion on hazard: the 48h EC50 for Daphnia of Peomosa is 177 mg/L. 

Data matrix: Peomosa results for acute Daphnia using read across fromDimethyl benzyl carbinol

Common names

Peomosa

Dimethyl benzyl carbinol

Cas no

19819-98-8

100-86-7

Chemical structure

Physico-chemical data

 

 

Molecular weight

136.94

150.22

Physical state

Liquid

Liquid

Vapour pressure (Pa)

1.9 (measured)

3.94 (EpiSuite)

Water solubility (mg/l)

12339(measured)

2029 (EpiSuite)

Log Kow(measured)

2.1

 No data

Log Kow (calculated - EpiSuite)

2.11

2.44

Acute Aquatic toxicity

 

 

Acute toxicity Daphnia (48-h) mg/l

Read across fromDimethyl benzyl carbinol

177