Arabinofuranosidase, α-l-

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

25-01-2016 to 08-02-2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

A reliability score of 2 was given since the study was not performed under GLP and the concentrations were not measured, but only given as nominal values.

Justification for type of information:

For industrial enzymes, the PNEC (predicted no effect concentration) value for enzymes in general is considered the highest dose tested for a given endpoint in studies conducted and published by the enzyme industry. The one exception is for proteases and oxidoreductases, where effects may be observed at lower concentrations. Similarly, although the acute fish study with catalase was not conducted GLP, the 72-hour effect concentration (ErC50) for arabinofuranosidase was greater than the limit dose of 100 mg/L. The weight-of-evidence indicates that enzymes in general are not ecotoxic.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Concentrations only given as nominal.

Qualifier:

according to guideline

Guideline:

ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)

Deviations:

yes

Remarks:

Concentrations only given as nominal.

Principles of method if other than guideline:

Only nominal concentrations.

GLP compliance:

no

Remarks:

See *justification for type of information'

Analytical monitoring:

no

Details on sampling:

- Concentrations: 6.25, 12.5, 25, 50, 100 TOS mg/L.

Vehicle:

no

Details on test solutions:

According to the MicroBiotests Inc SOP.

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Common name: Unicellular green algae
- Strain: Pseudokirchneriella subcapitata
- Source (laboratory, culture collection): MicroBiotests Inc. The algal growth inhibition bioassay has been developed by the research teams at the Laboratory for Biological Research in Aquatic Pollution (LABRAP) at the University of Ghent in Belgium.
- Method of cultivation: According to the MicroBiotests Inc. SOP.
Algae are supplied as de-immobilized algal beads.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23°C +/- 2 °C

pH:

8.1 +/- 0.2

Nominal and measured concentrations:

Nominal concentrations

Details on test conditions:

TEST SYSTEM
- Test vessel: 25 mL calibrated flask
- Material, size, headspace, fill volume: 25 mL
- Initial cells density: 1*10^4 algae/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes.
- Detailed composition if non-standard medium was used: As described in OECD Guideline 201and the ISO/DIS Guideline 8692.

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: Yes to pH 8.1
- Photoperiod: 72 h
- Light intensity and quality: 10000 lux for sideway illumination or min. 3000-4000 lux for bottom illumination

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: spectrophotometer

Reference substance (positive control):

no

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 27.2 other: mg TOS/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 100 other: mg TOS/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 27.2 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Details on results:

No significant growth inhibition and no abnormalities were observed.

Validity criteria fulfilled:

yes

Conclusions:

Arabinofuranosidase, batch PPH40331 up to a concentration of 100 mg/L (27.2 mg aep/L) was not toxic to Pseudokirchneriella subcapitata as no significant growth inhibition was observed in the present test system. Thus no 72h ErC50 could be calculated and must be > 100 mg TOS/L (> 27.2 mg aep/L).

Executive summary:

The purpose of this study was to screen for toxicity of arabinofuranosidase, batch PPH40331 towards algae. A 72h algal growth inhibition test is perfonned in long cell test vials with Pseudokirchneriella subcapitata. Algae are supplied as de-immobilized algal beads. The Algal toxkit test follows the prescriptions of the OECD "Algal growth inhibition test" (Guideline 201) and the ISO "Water Quality

- Freshwater Algal Growth Inhibition Tests with Unicellular Green Algae" (ISO Standard 8692). Endpoint of the study is percent inhibition (I%) of algal growth rate compared to the control.

IC50: Calculated/estimated 50% growth inhibition compared to control algae.

Arabinofuranosidase, batch PPH40331 up to a concentration of 100 mg/L (27.2 mg aep/L) was not toxic to Pseudokirchneriella subcapitata as no significant growth inhibition was observed in the present test system. Thus no 72h ErC50 could be calculated and must be > 100 mg TOS/L  (> 27.2 mg aep/L).

Description of key information

Arabinofuranosidase, batch PPH40331 up to a concentration of 100 mg/L (27.2 mg aep/L) was not toxic to Pseudokirchneriella subcapitata as no significant growth inhibition was observed in the present test system. Thus, no 72h ErC50 could be calculated and must be > 100 mg TOS/L  (> 27.2 mg aep/L). NOEC is 27.2 mg aep/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

27.2 mg/L