Trisodium bis[2-hydroxy-5-nitro-3-[[2-oxo-1-[(phenylamino)carbonyl]propyl]azo]benzenesulphonato(3-)]cobaltate(3-)

Toxicity to aquatic plants other than algae

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with analytical monitoring. Concentration-effect relationship ambiguous but acceptable.

Qualifier:

according to guideline

Guideline:

OECD Guideline 221 (Lemna sp. Growth Inhibition Test)

Deviations:

yes

Remarks:

The temperature ranged from 23.8 to 27.2 °C, which is slightly out of the required range of 24± 2 °C.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

To prepare the standard solutions, a stock solution (test item dissolved in ultra-pure water:acetonitrile (1:1, v:v)) was diluted with medium:methanol (8:2; v:v) containing 10 mM ammonium acetate. Test samples were diluted to obtain a final sample composition of sample:methanol (8:2, v:v) containing 10mM ammonium acetate before HPLC analysis.

Test organisms (species):

Lemna minor

Details on test organisms:

Test organism: Exponential growing plant monoculture of Lemna minor (Umweltbundesamt, FGIII 2.5, Überwachungsverfahren Abwasserentsorgung, Schichauweg 58, D-12307 Berlin)
Culture: All-glass vessel containing sterile Swedish standard-Medium (SIS Medium) and the exponentially growing plant monoculture.
Cultivation: At least seven days before testing, sufficient colonies were transferred aseptically into fresh sterile medium and cultured for 7-10 days under the conditions of the test.
Illumination: Continuous (6500–10000 lux) from Osram Fluora L18W77 (Osram AG, Winterthur, Switzerland) and CH Lighting F18T8/6500K EUP (CH Lighting CO., Ltd., China)
Temperature 24 ± 2 °C

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Test temperature:

24 ± 2 °C

pH:

6.5 at the beginning of the test

Dissolved oxygen:

Determined and reported.

Nominal and measured concentrations:

Prior to the definitive test a non-GLP range finding test with the nominal concentrations of 1, 10 and 100 mg/l of active ingredient was performed.
Based on the results of the non-GLP range finding test, the test concentrations for the definitive test were 326, 102, 31.8, 9.95 and 3.11 mg/l nominal concentration of the test item, corresponding to 250, 78.1, 24.4, 7.63 and 2.38 mg/l of the active ingredient.

Details on test conditions:

Test vessel: 400 ml beakers, all-glass, with 200 ml of test medium. The beakers were covered with black paper up until the 200 ml mark to ensure that illumination comes only from above and not from the sides.
Test medium: Swedish standard-Medium (SIS Medium), prepared with ultra-pure water
Pre-culture: Exponentially growing plant monoculture of Lemna minor (the culture was visibly free from contamination by other organisms such as algae and protozoa; only healthy Lemna minor plants with comprising 2-4 fronds were used).
Illumination Intensity: continuous (6500–10000 lux) from Osram Fluora L18W77 (Osram AG, Winterthur, Switzerland) and CH Lighting F18T8/6500K EUP (CH Lighting CO., Ltd., China) Homogeneity: ±15%
Incubation Beakers were incubated on a black non-reflecting surface.

Reference substance (positive control):

yes

Remarks:

3,5 dichlorophenol

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: nominal value analytically verified

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

196 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: nominal value analytically verified

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

6.38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

7 d

Dose descriptor:

EC10

Effect conc.:

3.36 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: nominal value analytically verified, 95%CL: n.d. - 8.67 mg/L)

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

88.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: nominal value analytically verified

Details on results:

EFFECT ON FROND NUMBERS:
With respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 55% at 250 mg/l, 32% at 78.1 mg/l and 14% at 24.4 mg/l. No significant effects were observed at the 7.63 and 2.38 mg/l concentrations. Based on these effects and the measured concentrations of the active ingredient, the median effect concentration with respect to the frond number’s growth rate (frond number ErC50) of the tested substance to Lemna minor was calculated to be 196 mg/l (95% confidence limits: 153–269 mg/l).
The ErC10 was 13.0 (6.56–20.4) mg/l; while the NOErC was determined to be 6.38 mg/l.

EFFECT ON DRY WEIGHT:
With respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 75% at 250 mg/l, 40% at 78.1 mg/l, 27% at 24.4 mg/l, 17% at 7.63 mg/l and 5% at 2.38 mg/l.
Based on these effects and the measured concentrations of the active ingredient, the median effect concentration with respect to the dry weight’s growth rate (dry weight r ErC50) of the tested substance to Lemna minor was calculated to be 88.4 mg/l (95% confidence limits: 35.1–251 mg/l). The ErC10 was 3.36 (0.012–13.3) mg/l. Due to the variation among replicates within the 3 lower concentrations, the NOErC was declared as not assessable.

Results with reference substance (positive control):

-

Validity criteria fulfilled:

yes

Conclusions:

EC50 = 196 mg/l
NOEC = 6.38 mg/l

Executive summary:

The inhibitory effects of Acid Yellow 194 to the duckweed Lemna minor were investigated over a period of 7 days, based on the frond number and biomass (dry weight), following the guideline OECD 221.

Based on the test results, the EC50 value was set at 196 mg/l.

Description of key information

The inhibitory effects of Acid Yellow to the duckweed Lemna minor were investigated over a period of 7 days, based on the frond number and biomass (dry weight), following the guideline OECD 221.

Based on the test results, the EC50 value was set at 196 mg/l and the NOEC value was set to 6.38 mg/l.

Key value for chemical safety assessment

EC50 for freshwater plants:

88.4 mg/L

EC10 or NOEC for freshwater plants:

3.36 mg/L