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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:
other information
Justification for type of information:
The short-term toxicity to aquatic invertebrates of the present target substance, dextransucrase IUBMB 2.4.1.5, has not been determined but another enzyme (Cellulase, IUBMB 3.2.1.4) has been analyzed and used as a source substance for read-across.
The conclusion is that the target substance dextransucrase IUBMB 2.4.1.5 is considered not to be acutely toxic to Daphnia magna.
Justification for read-across: Please see attached justification.
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 52.1 mg/L
Nominal / measured:
nominal
Conc. based on:
other: active ingredient/ active enzyme protein (aep)
Basis for effect:
mobility
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 March 2011 to 12 March 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Reliability 1
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Certificate included in report
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0 and 100 mg Total organic solids (TOS) per litre
- Sampling method: At the start from the test, three samples (15 mL) were taken from the freshly prepared control and test media. After 48 hours, the contents of the test vessels from each group were pooled and further three samples (15 mL) were taken for analysis.
- Sample storage conditions before analysis: Frozen
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance (878 mg) was dispersed in dilution medium (1L) in a volumetric flask. The contents of the flask were shaken before poured in to the test vessels.
- Controls: Medium
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia Magna
- Strain: Straus
- Source: Institute National de Recherche Chimique Appliqué (IRChA), France
- Age at study initiation (mean and range, SD): less than 24 hours old
- Method of breeding: Stock cultures are maintained in glass vessels containing approximately 0.5 to 0.8 litres of Elendt M4 culture medium in a temperature controlled laboratory at nominally 20 ± 2°C. A photperiod of 16 hours light: 8 hours dark, with periods of subdued light at the beginning and end of each light phase. Culture medium was renewed three times each week. Cultures were fed daily with a suspension of the unicellular green algae, Pseudokirchneriella subcapitata, to provide nominally 0.1 to 0.2 mg carbon per daphnid, per day. Culture conditions ensure that the stock animals reproduce by parthenogenesis. The day before the start of the test, all juvenile Daphnia were removed from the laboratory cultures. The following morning, juveniles produced by the egg-bearing adult Daphnia were removed from the culture vessels and held in a separate holding vessel. These animals were used in the test.
- Feeding during test: no


Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Hardness:
270 mg/L as CaCO3
Test temperature:
20.4-20.8°C
pH:
7.61-8.05
Dissolved oxygen:
40-99% ASV (air saturation value)
Nominal and measured concentrations:
nominal: 0 and 100 mg TOS/L
At the start of the test, enzyme recovery was 89% of the nominal value. After 48 hours the recovery decreased to 41% of nominal value.
Details on test conditions:
TEST SYSTEM
- Test vessel: glass dishes
- Type (delete if not applicable): loosely covered
- Material, size, fill volume: glass, 120 mL, 100 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: deionised, reverse osmosis water
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light: 8 hours dark with periods of subdued light at the beginning and at the end of each light phase


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Daphnia were considered immobile if they were unable to swim within approximmately 15 seconds following gentle agitation of the test vessel. The numbers of mobile, immobile and floating Daphnia were counted approximately 24 and 48 hours after the start of the study.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 1, 10 and 100 mg TOS/L
- Results used to determine the conditions for the definitive study: yes.
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: TOS (total organic solids)
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
>= 52.1 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Remarks:
active enzyme protein (aep)
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: TOS
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 52.1 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Remarks:
aep
Basis for effect:
mobility
Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the test, Cellulase was not found to be acutely toxic to Daphnia magna at a nominal concentration of 100 mg TOS/L equivalent to 52.1 mg aep/L.
Executive summary:

The acute toxicity of Cellulase to Daphnia magna was assessed under static exposure conditions.

The study was conducted in accordance with EC Methods for Determination of Ecotoxicity, Annex to Commission Regulation (EC) No 440/2008 Part C, Method 2 “Daphnia sp. Acute Immobilisation Test” and the OECD Guideline for Testing of Chemicals No. 202, “Daphnia Acute Immobilisation Test” (2004).

A group of twenty Daphnia, less than 24 hours old, was exposed for 48 hours to Cellulase at a nominal concentration of 100 mg TOS (Total Organic Solids)/L equivalent to 52.1 mg aep (active enzyme protein)/L. The test medium was prepared in Elendt M4 medium by the direct addition of the test substance to the dilution medium.

At the request of the Sponsor, the test concentration was verified by analysis of the enzyme concentration, which was performed at the Sponsor’s laboratory.

Observations of the Daphnia in each control and test vessel were made after 24 and 48 hours.

No immobilisation or adverse effects on the Daphnia were noted at a nominal concentration of 100 mg TOS/L.

Based on these findings the following values have been estimated:

48-hour EC50 value :                                   >100 mg TOS/L or > 52.1 mg aep/L

“No observed effect concentration” :            ≥ 100 mg TOS/L or 52.1 mg aep/L

Description of key information

Under the conditions of the test, Cellulase (structural analogue) was not acutely toxic to Daphnia magna and thus the EC50 value could not be determined and must be above the highest exposure concentration of 100 mg TOS (total organic solids)/L equivalent to 52.1 mg aep(active enzyme protein)/L.

Because all enzymes are built up of amino acids, the physical and chemical characteristics are very similar for different enzymes, and hence read-across from other enzymes should be fully applicable. In general, enzymes exhibit the same ecotoxicological properties which are confirmed by ecotoxicity studies performed in the industry.

Therefore, Dextransucrase is considered not to be acutely toxic to Daphnia magna.

Key value for chemical safety assessment

Additional information

The acute toxicity of Cellulase to Daphnia magna was assessed under static exposure conditions.

The study was conducted in accordance with EC Methods for Determination of Ecotoxicity, Annex to Commission Regulation (EC) No 440/2008 Part C, Method 2 “Daphnia sp. Acute Immobilisation Test” and the OECD Guideline for Testing of Chemicals No. 202, “Daphnia Acute Immobilisation Test” (2004).

A group of twenty Daphnia, less than 24 hours old, was exposed for 48 hours to Cellulase at a nominal concentration of 100 mg TOS (Total Organic Solids)/L equivalent to 52.1 mg aep (active enzyme protein)/L. The test medium was prepared in Elendt M4 medium by the direct addition of the test substance to the dilution medium.

At the request of the Sponsor, the test concentration was verified by analysis of the enzyme concentration, which was performed at the Sponsor’s laboratory.

Observations of the Daphnia in each control and test vessel were made after 24 and 48 hours.

No immobilisation or adverse effects on the Daphnia were noted at a nominal concentration of 100 mg TOS/L.

Based on these findings the following values have been estimated:

48-hour EC50 value :                                   >100 mg TOS/L or > 52.1 mg aep/L

“No observed effect concentration” :            ≥ 100 mg TOS/L or 52.1 mg aep/L