Pidolic acid

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot no.of test material: 20140124
- Expiration date of the lot/batch: 22 May 2019
- Purity test date: 22 May 2017

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient temperature
- Stability under test conditions: No data

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Nominal 4.24, 9.39, 20.7, 45.5 and 100mg/L
- Sampling method: Three replicate samples (duplicate samples for analysis and 1 reserve sample) were taken from freshly prepared test solutions at 0h and from aged 72h pooled samples. Duplicate samples (1 sample for analysis and 1 reserve sample) were taken from test vessels at 24 and 48h.
- Sample storage conditions before analysis: All samples were frozen on day of sampling until required for analysis

Vehicle:

no

Details on test solutions:

Nominal 500mg/L stock solution of test substance prepared in OECD test medium. Test solutions prepared by dilution from 500 mg/L stock solution

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa (CCAP)
- Age of inoculum (at test initiation): 6 days

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

No data

Test temperature:

22+/-2oC

pH:

0h: 4.1-7.9
72h: 7.9-8.0

Dissolved oxygen:

No data

Salinity:

No data

Conductivity:

No data

Nominal and measured concentrations:

Nominal test concentrations (0h): Control, 4.27, 9.39, 20.7, 45.5 and 100 mg/L
Geometric mean measured test concentrations (72h): Control, 0.20, 0.30, 0.45, 0.66 and 4.41 mg/L

Details on test conditions:

TEST SYSTEM
- Material, size, headspace: Glass 250 mL conical flasks with foam bungs
- Fill volume: 100 mL
- Aeration: None but vessels were continuously shaken at 150 rpm (nominal)
- Initial cells density: 1 x 10/4 cells/mL
- Control end cells density:
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): Not applicable

GROWTH MEDIUM
- Standard medium used: Yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
- Total organic carbon:
- Particulate matter:
- Metals:
- Pesticides:
- Chlorine:
- Alkalinity:
- Ca/mg ratio:
- Conductivity:
- Culture medium different from test medium:
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH:
- Photoperiod:
- Light intensity and quality:
- Salinity (for marine algae):

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]
- Chlorophyll measurement:
- Other:

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 4.41 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.66 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 4.41 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

>= 2.81 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.66 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

>= 4.41 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): Yes (16x growth)
- Observation of abnormalities (for algal test): No data
- Unusual cell shape: No data
- Colour differences: No data
- Flocculation: No data
- Adherence to test vessels: No data
- Aggregation of algal cells: No data
- Any stimulation of growth found in any treatment: No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: None

Validity criteria fulfilled:

yes

Conclusions:

The 72 hour ErC50 (growth rate) was determined as >4.41 mg/L and the EyC50 (biomass) was determined to be 2.81 mg/L based on geometric mean measured test concentrations

Executive summary:

In a 72 -hour toxicity study the green alga, Pseudokirchenriella subcapitata, was exposed to a range of test concentrations under static conditions in accordance with the OECD test guideline 201 and in compliance with GLP. The nominal test concentrations were a control and 4.27, 9.39, 20.7, 45.5 and 100 mg/L, with geometric mean measured test concentrations of 0.20, 0.30, 0.45, 0.66 and 4.41 mg/L, respectively.

A statistically significant inhibition in growth rate and yield (biomass) was observed at the geometric mean measured concentration of 4.41 mg/L. The ErC50 was >4.41 mg/L and the EyC50 was 2.81 mg/L.

This toxicity study is considered acceptable and satisfies the guideline requirements for an algal growth inhibition test.

Description of key information

In a reliable 72 -hour toxicity study the green alga, Pseudokirchenriella subcapitata, was exposed to a range of test concentrations under static conditions, in accordance with the OECD test guideline 201 and in compliance with GLP.

A statistically significant inhibition in growth rate and yield (biomass) was observed at the geometric mean measured concentration of 4.41 mg/L. The ErC50 was >4.41 mg/L and the EyC50 was 2.81 mg/L.

This toxicity study is considered acceptable and satisfies the guideline requirements for an algal growth inhibition test.

Key value for chemical safety assessment

EC50 for freshwater algae:

2.81 mg/L