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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:
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
Please refer to the Read-across statement attached under section 13.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This Read-Across is based on the hypothesis that the target and the source substances have similar environmental fate and (eco)toxicological properties, because both substances have the same common compound octyl sulfonate while another main constituent of the target substance octyl disulfonate is considered to have similar level of toxicity as octyl sulfonate. Other non-common compounds represented by impurities are considered not to influence the read-across validity because they are either structurally identical in the target and in the source substances or, if different, do not contribute to the toxicity effects because they are also anionic sulfonates with the same functional groups and their content is very low.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to the Read-across statement attached under section 13.

3. ANALOGUE APPROACH JUSTIFICATION
The aquatic toxicity of the ANS category members is influenced mainly by the length of alkyl chain. Numerous studies demonstrate increasing toxicity with the chain length. Since all sulfonate containing constituents of the target substance are octyl derivatives, they are considered not to possess higher toxicity potential to aquatic environment than the source substance. Taking into account the similar predicted environmental fate and behavior as well as the similar mode of ecotoxic action due to its surfactant properties, the second sulfonate group of the main constituent octyl disulfonate is considered not to result in a higher toxicity to aquatic life than the source substance. Thus, the results of the acute toxicity study in aquatic invertebrates available for the source substance are considered to be the same if a study with the target substance was conducted.

4. DATA MATRIX
Please refer to the Read-across statement attached under section 13.
Reason / purpose:
read-across source
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
421 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: 95% Confidence Interval: 372 - 472 mg/L
Remarks:
predicted result from the source substance
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 500 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: predicted result from the source substance
Details on results:
Daphnia in the negative control group appeared normal throughout the test, with no mortality/immobility or clinical signs of toxicity observed throughout the test. All daphnids in the 65 mg/L treatment group also appeared normal throughout the test, with no mortality/immobility or overt signs of toxicity observed. All daphnids in the 108 and 180 mg/L treatment groups appeared normal throughout the test, with the exception of two lethargic daphnid noted in each of these treatment groups at test termination. Percent mortality/immobility at test termination in the 300 and 500 mg/L treatment groups were 5 and 80%, respectively. All surviving daphnids in the 300 and 500 mg/L treatment groups were lethargic at test termination.

Table 2: Cumulative Mortality, Immobility and Observations

Nominal Test Concentration (mg/L)

Replicate

Daphnia/Replicate

5 Hours

24 Hours

48 Hours

Percent Immobile and Dead

 

 Number Dead1

 

 

Number Immobile

Effects2

Number Dead1

Number Immobile

Effects2

Number Dead1

Number Immobile

Effects2

Negative Control

A

10

0

0

10 AN

0

0

10AN

0

0

10AN

0

 

B

10

0

0

10AN

0

0

10AN

0

0

10AN

65

A

10

0

0

10AN

0

0

6AN; 4Q,AN

0

0

10AN

0

 

B

10

0

0

8AN; 2Q,AN

0

0

6AN; 4Q,AN

0

0

10AN

108

A

10

0

0

10AN

0

0

5AN; 5Q,AN

0

0

10AN

0

 

B

10

0

0

10AN

0

0

7AN; 3Q,AN

0

0

8AN; 2C

180

A

10

0

0

8AN; 2QAN

0

0

4AN; 6Q,AN

0

0

9AN;1Q.AN

0

 

 B

10

0

0

10AN

0

0

5AN; 4Q,AN; 1C

0

0

8AN; 2Q,C

300

A

10

0

0

10AN

0

0

6AN; 4Q,AN

1

0

1Q,C; 8C

5

 

B

10

0

0

9AN; 1Q,AN

0

0

8AN; 2Q,AN

0

0

10C

500

A

10

0

0

10AN

0

0

2Q,C; 8C

6

0

4C

80

 

B

10

0

0

10AN

0

0

1Q,C; 9C

10

0

----

1   Cumulative number of dead daphnia.

2   Observed Effects: AN = appear normal; Q,AN = trapped at water surface but appear normal after submersion below the water's surface;

Q,C = trapped at water surface and appearlethargic after submersion below the water's surface; C = lethargy.

 

Validity criteria fulfilled:
yes
Conclusions:
The same result is predicted for the target substance.
The cladoceran, Daphnia magna, was exposed for 48 hours under static conditions to five nominal concentrations of the source substance sodium octane-1-sulphonate monohydrate (EC 226 -195 -4; CAS 5324 -84 -5) ranging from 65 to 500 mg/L. The 48-hour EC50 value was 421 mg/L, with a 95% confidence interval of 372 to 472 mg/L. The slope of the concentration-response curve was 11.212.
Executive summary:

The objective of this study was to determine the acute effects of the source substance sodium octane-1-sulphonate monohydrate (EC 226 -195 -4; CAS 5324 -84 -5) on the cladoceran, Daphnia magna. The protocol was based on procedures outlined in the OECD Guideline for Testing of Chemicals, 202: Daphnia sp. Acute Immobilization Test and Reproduction Test. The study was performed under GLP conditions with deviations. Daphnia magna, was exposed for 48 hours under static conditions to five nominal concentrations ranging from 65 to 500 mg/L. The EC50 (48 h) value was 421 mg/L, with a 95% confidence interval of 372 to 472 mg/L. The slope of the concentration-response curve was 11.212.

Description of key information

Read-across: OECD 202, GLP, D. magna, EC50 (48 h) = 421 mg/L (nominal)

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
421 mg/L

Additional information

The objective of this study was to determine the acute effects of sodium octane-1-sulphonate monohydrate (EC 226 -195 -4; CAS 5324 -84 -5) on the cladoceran Daphnia magna.The protocol was based on procedures outlined in the OECD Guideline for Testing of Chemicals, 202: Daphnia sp. Acute Immobilization Test and Reproduction Test. The study was performed under GLP conditions with deviations.Daphnia magna was exposed to five nominal concentrations ranging from 65 to 500 mg/L under static conditions for 48 hours.

The EC50 (48 h) value was 421 mg/L, with a 95 % confidence interval of 372 to 472 mg/L. The slope of the concentration-response curve was 11.212.