3-hydroxy-2-methylquinoline-4-carboxylic acid

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted March 23, 2006, updated Annex 5, 28 July 2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

3-hydroxy-2-methylquinoline-4-carboxylic acid

EC Number:

204-198-1

EC Name:

3-hydroxy-2-methylquinoline-4-carboxylic acid

Cas Number:

117-57-7

Molecular formula:

C11H9NO3

IUPAC Name:

3-hydroxy-2-methylquinoline-4-carboxylic acid

Test material form:

solid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Samples from the test solutions were analysed to determine actual levels of the test item in solution at start of exposure period (time 0 hours) and at the end of the exposure at 72 hours.
Samples of stock solution and test solutions were taken to determine the actual test item concentrations in comparison to the nominally applied concentrations.
Control and test solutions were sampled in duplicate. The duplicate samples were kept separately as a reserve. The volume of each sample was recorded.
Control and test solutions were sampled in duplicate. The duplicate samples were kept as a reserve. Samples of a defined volume (10 mL) were taken from the designated test solution mixed with 10 mL acetonitrile.
After sampling the samples were stabilised by adding acetonitrile in a 1:1 (v:v) relation. All samples were stored in glass bottles in the dark at a temperature of 5 -18°. A record was
kept for each sample.

Test solutions

Vehicle:

no

Details on test solutions:

Test concentrations (nominal): 6.25, 12.5, 25.0, 50.0 and 100 % of a filtrate at
100 mg test item /L and a control; these
concentration levels correspond to the following
nominal test concentrations, assuming full solubility
of the test item in the test medium: 6.25, 12.5,
25.0, 50.0 and 100 mg test item/L

Test organisms

Test organisms (species):

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

Details on test organisms:

The test system used in this study was the freshwater algae Pseudokirchneriella subcapitata
(SAG 61.81).
The organisms were originally supplied by Sammlung von Algenkulturen, Albrecht-von-Haller-Institut, Universität Göttingen, Germany.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Test temperature:

Temperature in the test room: 21-24 C; (measured: 22.6-22.8 °C)

pH:

pH-value of the algal medium: 7.9-8.1
pH in test solutions at test start: 7.0-7.7
pH in test solutions at test end: 8.1-8.2

Salinity:

Culture medium: Mod. OECD medium (OECD 201, EN ISO 8692)

Details on test conditions:

Light: Permanent illumination (24/0 h light/dark); Econlux LED
Sunstrip "daylight"
Light intensity: 60-120 pE rn-2s-1; (measured: 69.3-73.32 pE m-2s-1)
Shaker: 100±5 oscillations/min

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

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

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The %-inhibition seen for the parameter growth rate was <5%. Therefore, the E010
and the E050 was stated to be higher than the highest tested concentration level (mg 3-
Hydroxy-2-methy1-4-quinolinecarboxylic acid/L).

The inhibition of growth rate determined at the two highest treatment levels (50.0
and 100% of a saturated solution at a loading rate of 100 mg/L) was 1.2% and 2.6%, resp.,
with %Minimum Detectable Difference (MDD) of 0.8% and 1.0%, resp. of the statistical
method used. Therefore, this inhibition was determined to be statistically significant.
Nevertheless, this inhibition can be considered to be of minor biological relevance. The
statistically evaluated NOEC and LOEC values are therefore considered not biologically
relevant. In the light of this minor biological relevance, a NOEC of 100% of a saturated
solution at a loading rate of 100 mg/L, and an E010 of > 100% of a saturated solution at a
loading rate of 100 mg/L, taking into account the measured concentrations are deemed the
more reliable endpoints.

Any other information on results incl. tables

Analytical findings

Samples from the test solutions were analysed to determine actual levels of the test item in

solution at start of exposure period (time 0 hours) and at the end of the exposure at 72 hours.

At time 0 hours the measured concentrations range between 90.1-99.1% of the nominal

concentrations (at a loading rate of 100 mg/L) and 90.3-97.1% after 72 hours. Therefore, the

test item concentrations considered to be stable within ± 20% based on nominal

concentration throughout the exposure period. As a consequence and since all concentration

levels were measured, the biological results are calculated and reported based on nominal

concentrations given in % of a saturated solution at a loading rate of 100 mg/L, equivalent to

mg test item/L.

Biological findings

No meaningful concentration-response relationship was observed for both biological

parameters growth rate and yield during the exposure period. The relevant results for inhibition of growth are presented in the following table:

Nomincal conc. (mg/L)	Mean growth rate (1/d)	# replicates	% inhibition
control	2.0089	6
6.25	2.0088	3	0.0
12.5	2.0191	3	-0.5
25	2.0024	3	0.3
50	1.9849	3	1.2
100	1.9561	3	2 .6

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Mean biomass increase in the control cultures: factor of at least 16 within the test period found: 414.4 Mean coefficient of variation for section-by-section specific growth rates : up to 35%, found: 10.5% Coefficient of variation up to 7%; found: 0.4%

Conclusions:

No meaningful concentration-response relationship was observed for both biological parameters growth rate and yield during the exposure period. The EC50 and EC10 values were determined to be >100 mg/L.

Executive summary:

In a test according to OECD 201 algae Pseudokirchneriella subcapitata were exposed to 5 concentrations up to 100 mg of 3-Hydroxy-2-methyl-4-quinolinecarboxylic acid per litre. Analytical monitoring at test start and test end revealed recoveries in the range of 100%. Growth rate of algae was not affected at all in all test concentrations.