Nuclease, deoxyribo-

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:

10-13 November 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

ALGALTOXKIT F™ Freshwater Toxicity supplied by MicroBioTests Inc.

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

ALGALTOXKIT F™ Freshwater Toxicity supplied by MicroBioTests Inc.

Deviations:

no

GLP compliance:

no

Remarks:

The study was performed in House according to OECD TG and ISO standards and in the spirit of GLP but without QA audit.

Analytical monitoring:

no

Details on sampling:

- Concentrations: 10, 50, 100, 150, 200 mg/L.
- Sampling method: According to the MicroBiotests Inc SOP.

Vehicle:

no

Details on test solutions:

According to the MicroBiotests Inc SOP.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella 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:

20-21

pH:

Within limits.

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: According to the formula of the OECD Guideline 201 "Alga, Growth Inhibition Test" and the ISO/DIS Guideline 8692 "Water Quality - Freshwater Algal Growth Inhibition Tests with Unicellular Green Algae".

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: yes
- 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

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 5.4 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 5.4 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:

Under the conditions of the test, deoxyribonuclease (phosphodiesterase), batch PPW3748 was found to be slightly toxic to Pseudokirchneriella subcapitata, but no 72h ErC50 could be determined and thus is > 200 mg/L (>5.4 mg aep/L).

Executive summary:

The purpose of this study was to screen for toxicity of Phosphodiesterase, batch PPW37486 towards algae. A 72h algal growth inhibition test is performed 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.

Validity: OECD 201 in turn indicates that the control growth rate must be at least 0.92 per day, i.e. a multiplication factor of 16.

Under the conditions of the test, deoxyribonuclease (phosphodiesterase), batch PPW3748 was found to be slightly toxic to Pseudokirchneriella subcapitata, but no 72h ErC50 could be determined and thus is > 200 mg/L (>5.4 mg aep/L).

Description of key information

Deoxyribonuclease (phosphodiesterase), batch PPW3748 was found to be slightly toxic to Pseudokirchneriella subcapitata, but no 72h ErC50 could be determined and thus is > 200 mg/L (>5.4 mg aep/L).