3-pyridylmethanol

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:

from 2017-08-21 to 2017-09-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

TOXI-COOP ZRT., 8230 Balatonfüred, Arácsi út 97., Hungary

Analytical monitoring:

yes

Remarks:

HPLC-UV

Details on sampling:

For determination of the test item concentrations, three replicate samples (5 mL per replicate) were taken from each test concentration and from the control at the start and at the end of the test.

Vehicle:

no

Details on test solutions:

The test solutions used in the test was prepared by mechanical dispersion without using any solubilising agents. A stock solution was first prepared by dissolving an amount of 0.08 g test item in 800 mL dilution water (OECD Medium) to obtain the nominal concentration of 100 mg/L. The test solutions of subsequent lower test concentrations were prepared by appropriate diluting of this stock solution.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: 61.81 SAG
- Source: Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany
- Age of inoculum (at test initiation): 4 days

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

climate chamber: 22.4 - 23.9 °C
in the flasks: 22.7 - 23.1 °C

pH:

7.96 - 9.35

Salinity:

NA

Nominal and measured concentrations:

Nominal concentrations: 0.4, 1.2, 3.7, 11.1, 33.3 and 100 mg/L
Calculated geometric mean measured concentrations: 0.33, 1.07, 3.46, 10.6, 32.0 and 95.7 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Material, size, headspace, fill volume: glass, ~250 mL volume, 100 mL test medium
- Initial cells density: 1 x 10^4 cells/mL
- Control end cells density: 126.50 x 10^4 cells/mL
- No. of organisms per vessel: 0.1 mL algal biomass (10^7 algal cells per mL)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: OECD Medium prepared according to OECD 201

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuously illuminated
- Light intensity and quality: 8038 lux

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3
- Range finding study; yes
- Test concentrations: 0.1, 1, 10, 100 mg/L

EFFECT PARAMETERS MEASURED :
- Determination of cell concentrations: microscope with counting chambe at 24, 48 and 72 hours

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

12 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.:

> 100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.22 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

yield

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

33.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

yield

Details on results:

No morphological abnormalities were observed in the control and in the two lowest concentrations of 0.33 and 1.07 mg/L (measured).
Swollen and thin cells were observed in the concentrations of 3.46, 10.6, 32.0 and 95.7 mg/L (measured) together with the normal cells during the test.

Results with reference substance (positive control):

The date of the last study with the reference item Potassium dichromate was: 07 – 10 March 2017. The following results were obtained:
The 72h ErC50: 0.99 mg/L, (95 % confidence limits: 0.68 – 1.49 mg/L)
The 72h EyC50: 0.59 mg/L, (95 % confidence limits: 0.47 – 0.75 mg/L)

Validity Criteria

Cell density in the control cultures increased by a factor of more than 16 (by a factor of 126.50) within 72 hours. This corresponds to a specific growth rate of 1.61 day^-1.

The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72 h-tests) in the control cultures did not exceed 35 %.

- CV for section-by-section growth rate day 0-1: 12.68 %

- CV for section-by-section growth rate day 1-2: 9.93 %

- CV for section-by-section growth rate day 2-3: 6.94 %

The mean coefficient of variation for section-by-section specific growth rates: 9.85 %.

The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures did not exceed 7 % in test.

- CV for average specific growth rate day 0-3: 3.39 %

Validity criteria fulfilled:

yes

Conclusions:

In a 72-h algal growth inhibition test the EC50 based on growth rate was determined to be above 100 mg/L, and the EC10 was 12 mg/L, respectively.

Executive summary:

The effect of the test item on the growth of a unicellular green algal species Raphidocelis subcapitata was determined according to OECD 201, Regulation (EC) No. 226/2016 Method C.3 and EPA OPPTS 850.5400 and under GLP. The study was conducted under static conditions with an initial cell density of 1x10^4 cells/mL for a period of 72 hours. A stock solution of 100 mg/L was freshly prepared with OECD Medium and shaken until the test item was completely dissolved. Six concentrations were tested in a geometrical series with a dilution factor of 3 (nominal): 0.4 - 1.2 - 3.7 - 11.1 - 33.3 - 100 mg/L. The measured concentrations of the test item in the fresh media (0 h) were in the range of 98 to 100 % of the nominal values and in the old media (72 h) were in the range of 71 to 94 % of the nominal values of all concentrations.The measured concentrations deviated more than 20 % from the nominal in the two lowest concentrations at the end of the test, therefore, the geometric mean of the measured start and end concentrations was calculated to determine exposure concentrations.The EC50-values for inhibition of growth rate (ErC50) was >100 mg/L and for inhibition of yield (EyC50) was 33.1 mg/L. The EC10 value with 95% confidence interval was determined to be 12.0 mg/L (7.7 – 18.5 mg/L) based on growth rate (ErC10) and 0.22 mg/L (0.04 - 0.58 mg/L) based on yield (EyC10).

Description of key information

In a 72-h algal growth inhibition test the EC50 based on growth rate was determined to be above 100 mg/L, and the EC10 was 12 mg/L, respectively.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

12 mg/L

Additional information

The effect of the test item on the growth of a unicellular green algal species Raphidocelis subcapitata was determined according to OECD 201, Regulation (EC) No. 226/2016 Method C.3 and EPA OPPTS 850.5400 and under GLP (reference 6.1.5-1). The study was conducted under static conditions with an initial cell density of 1x10^4 cells/mL for a period of 72 hours. A stock solution of 100 mg/L was freshly prepared with OECD Medium and shaken until the test item was completely dissolved. Six concentrations were tested in a geometrical series with a dilution factor of 3 (nominal): 0.4 - 1.2 - 3.7 - 11.1 - 33.3 - 100 mg/L. The measured concentrations of the test item in the fresh media (0 h) were in the range of 98 to 100 % of the nominal values and in the old media (72 h) were in the range of 71 to 94 % of the nominal values of all concentrations. The measured concentrations deviated more than 20 % from the nominal in the two lowest concentrations at the end of the test, therefore, the geometric mean of the measured start and end concentrations was calculated to determine exposure concentrations. The EC50-values for inhibition of growth rate (ErC50) was >100 mg/L and for inhibition of yield (EyC50) was 33.1 mg/L. The EC10 value with 95% confidence interval was determined to be 12.0 mg/L (7.7 – 18.5 mg/L) based on growth rate (ErC10) and 0.22 mg/L (0.04 - 0.58 mg/L) based on yield (EyC10).