Pyridine-2-carbaldehyde

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:

2018-03-14 to 2018-05-15

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:

2006, corrected 2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Analytical samples were taken and analysed from control and all test item concentrations at 0 hours (initial value) from fresh test solutions and after 72 hours from aged test solutions.

Vehicle:

no

Details on test solutions:

A stock solution of 1000mg/L was prepared. Lower test solutions were prepared by dilution of a stock solution with test medium. Algae were added to each solution individually targeting nominal cell densities of 0.5 × 10^4 cells per mL in each solution.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Pseudokirchneriella subcapitata Hindák (Sphaeropleales: Selenastraceae)
- Strain: SAG 61.81
- Source (laboratory, culture collection): MBM Sciencebridge GmbH, Göttingen
- Method of cultivation: The algae are grown semi-continuously in sterile cultures in the laboratory.

ACCLIMATION
- Acclimation period: 3 to 4 days before start of the test, test medium was inoculated with the test organism and held under test conditions in order to produce a pre-culture in the state of exponential growth.
- Culturing media and conditions (same as test or not): yes

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.6 – 23.2 °C

pH:

7.54 – 8.45 (control)
7.50 - 8.55 (test concentrations)

Nominal and measured concentrations:

nominal: 100, 31.3, 9.77, 3.05, 0.954 mg/L and control
geometric mean measured: 95.8, 27.5, 5.45, 0.209, 0.114 mg/L and a control
The measured initial concentrations of the test item ranged from 90 % to 101 % of nominal. In the aged samples the measured concentrations were between

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks (100 mL) with aluminium caps were filled up with ~ 50 mL test solution
- Aeration: continuous agitation
- Initial cells density: 0.5 × 10^4 cells/mL.
- Control end cells density: 48.50 × 10^4 cells/mL.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes AAP-Medium ((according to Annex 3 of OECD 201))

OTHER TEST CONDITIONS
- Photoperiod: Continuously
- Light intensity and quality: 88.3 µEm-2s-1 (mean)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: fluorescence measurement (fluorescence microplate reader (infinite 200Pro) with an emission wavelength of 670 nm and evaluated with Tecan i-control (Software for Tecan Readers Tecan i-control, 1.11.1.0).)

Reference substance (positive control):

yes

Remarks:

Potassium Dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

17.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2.12 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

5.45 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

27.5 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.34 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.209 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

5.45 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Results with reference substance (positive control):

- Results with reference substance valid? yes (potassium dichromate)
- ErC50: 0.971 mg/L
- EyC50: 0355 mg/L

Table 1: Average cell numbers for each sampling time and concentration

Conc.	Average cell numbers [10^4/mL]
[mg/L]	0 h	24 h	48 h	72 h
Control	0.54	1.77	10.40	48.50
0.954	0.54	1.98	10.27	45.92
3.05	0.54	1.64	9.50	40.20
9.77	0.54	1.46	5.92	21.35
31.3	0.54	1.15	3.12	4.06
100	0.54	0.62	0.47	0.29

Table 2: Percentage inhibition of growth rate

Conc.	% Inhibition of growth rate
[mg/L]	0 h – 24 h	0 h –48 h	0 h – 72 h
Control	0.0	0.0	0.0
0.954	-9.6	0.7	1.4
3.05	5.9	3.4	4.6
9.77	15.2	19.5	20.2
31.3	35.8	40.7	55.2 *
100	91.1	105.1	115.0 *^1)

¹⁾Value was set to 100 for EC_{10, 20, 50}-calculation

* Statistically significant different to the control

Table 3: Percentage inhibition of yield

Conc.	% Inhibition of yield
[mg/L]	0 h – 24 h	0 h – 48 h	0 h – 72 h
Control	0.0	0.0	0.0
0.954	-17.1	1.3	5.4
3.05	10.6	9.1	17.3
9.77	25.2	45.4	56.6 *
31.3	50.4	73.8	92.7 *
100	93.5	100.7	100.5 *^1)

¹⁾Value was set to 100 for EC_{10, 20, 50}-calculation

* Statistically significant different to the control

Table 4: Determined concentration of the test item

Test item nominal [mg/L]	Sampling	Pyridine-2-aldehyde found			Actual test item conc. [mg/L]
		[mg/L]	% of nominal	Geometric mean [%]
Control	0 h fresh	< LOD	-	-	-
	72 h aged	< LOD	-
0.954	0 h fresh	0.860	90.1	11.9	0.114
	72 h aged	< LOD	-^1)
3.05	0 h fresh	2.92	95.7	6.86	0.209
	72 h aged	< LOD	-^1)
9.77	0 h fresh	8.73	89.4	55.8	5.45
	72 h aged	3.40	34.8
31.3	0 h fresh	30.7	98.1	87.8	27.5
	72 h aged	24.6	78.6
100	0 h fresh	101	101	95.8	95.8
	72 h aged	90.8	90.8

 - = not calculated; LOD = 0.0150 mg/pyridine-2-aldehyde; LOQ = 0.0500 mg/L pyridine-2-aldehyde

¹⁾Analyte was below LOD in the sample. Therefore the LOD value was used for calculation of geometric mean according to OECD Guidance document No. 23 (2000)

Validity criteria fulfilled:

yes

Conclusions:

The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 17.4 mg/L and 3.34 mg/L, respectively. The EC10-values for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours were 2.12 mg/L and 0.160 mg/L, respectively. The NOEC and LOEC for inhibition of growth rate after 72 hours were 5.45 and 27.5 mg/L, respectively. The NOEC and LOEC for inhibition of yield after 72 hours were 0.209 and 5.45 mg/L. All results are based on geometric mean measured values.

Description of key information

After 72 hours an ErC50 value of 17.4 mg/L and an EyC50 value of 3.34 mg/L were determined for the substance according to OECD 201. In addition, an NOEC for inhibition of growth rate of 5.45 mg/L and an ErC10 of 2.12 mg/L was determined.

Key value for chemical safety assessment

EC50 for freshwater algae:

17.4 mg/L

EC10 or NOEC for freshwater algae:

2.12 mg/L