Disodium 3-[(5-chloro-2-phenoxyphenyl)azo]-4-hydroxy-5-[[(p-tolyl)sulphonyl]amino]naphthalene-2,7-disulphonate

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

Study period:

From June 12 to June 22, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 221 (Lemna sp. Growth Inhibition Test)

Deviations:

yes

Remarks:

Spacing factor between concentrations >3.2

Qualifier:

according to guideline

Guideline:

other: EU Method C.26

GLP compliance:

yes (incl. QA statement)

Test organisms (species):

Lemna minor

Details on test organisms:

TEST ORGANISM- Source (laboratory, culture collection): Umweltbundesamt, FGIII 2.5, Überwachungsverfahren Abwasserentsorgung, Schichauweg 58, D-12307 Berlin- Culture: All-glass vessel containing sterile STEINBERG medium and the exponential growing plant monoculture- 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- Control of sensitivity: Yearly, with 3,5-dichlorophenol

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Test temperature:

25 °C

pH:

(day 0) pH = 5.5 in all test concentrations(day 7) pH = 6.4 for the blank control, 6.4 at 10 mg/l, 6.0 at 100 mg/l and 5.9 at 1000 mg/l.

Nominal and measured concentrations:

Nominal concentrations: 11.4, 114 and 1140 mg/l of Substance (corresponding to 10, 100 and 1000 mg/l of the active ingredient (AI))

Details on test conditions:

TEST SYSTEM- Incubation: Beakers were incubated on a black non-reflecting surface.- Test vessel: 400 ml beakers, all-glass, with 200 ml of test medium. The beakers are covered with black paper up until the 200 ml mark to ensure that illumination comes only from above and not from the sides.- Starting frond number: 9 fronds per replicate, 2-4 fronds per plant- No. of vessels per concentration: three.- No. of vessels per control: six.GROWTH MEDIUM- Culture: The nominal concentrations were prepared by dilution of a stock solution of the test item in STEINBERG medium.TEST MEDIUM / WATER PARAMETERS- Test medium: STEINBERG medium. KNO3: 350 mg/l KH2PO4: 90 mg/l K2HPO4 x 3H2O: 16.5 mg/l MgSO4 x 7H2O: 100 mg/l Ca(NO3)2 x 4H2O: 295 mg/l H3BO3: 120.0 µg/l ZnSO4 x 7H2O: 180.0 µg/l Na2MoO4 x 2H2O: 44.0 µg/l MnCl2 x 4H2O: 180.0 µg/l FeCl3 x 6H2O: 760.0 µg/l C10H14N2Na2O8 x 2H2O: 1500.0 µg/lOTHER TEST CONDITIONS- Adjustment of pH: The pH of the STEINBERG medium was adjusted before the test (pH 5.5 ± 0.2). Blanks of test medium without test item served as controls.- Photoperiod: Continuous (The light intensity was 6580–8100 lux (mean 7150 lux) at the start of the test and 6710–7590 lux (mean 6990 lux). ) from Osram Fluora L18W77 (Osram AG, Winterthur, Switzerland) and CH Lighting F18T8/6500K EUP (CH Lighting CO., Ltd., China).

Reference substance (positive control):

no

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

> 100 - < 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: Frond numbers

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

ca. 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Remarks on result:

other: Frond numbers

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: Frond numbers

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

< 10 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Remarks on result:

other: Frond numbers

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

> 100 - < 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: Dry weight

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

ca. 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Remarks on result:

other: Dry weight

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Remarks on result:

other: Dry weight

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

< 10 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Remarks on result:

other: Dry weight

Effects on frond numbers

With respect to growth rate inhibition for the endpoint frond numbers, the following effects as compared to the untreated controls were observed: 19 % at 100 mg/l and 75 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test.With respect to yield inhibition for the endpoint frond numbers, the following effects as compared to the untreated controls were observed: 18 % at 10 mg/l, 41 % at 100 mg/l and 92 % at 1000 mg/l.

Effects on dry weight

With respect to growth rate inhibition for the endpoint dry weight, the following effects as compared to the untreated controls were observed: 20 % at 100 mg/l and 67 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test. With respect to yield inhibition for the endpoint dry weight, the following effects as compared to the untreated controls were observed: 22 % at 10 mg/l, 44 % at100 mg/l and 90 % at 1000 mg/l.

 

Appearance of the test and control plants at the end of the test

In the control the plants were large with long roots, and looked bright green. At 10 and 100 mg/l, the plants were darker than the blanks, with smaller leaves. At 1000 mg/l, the plants had very small leaves, partially colored in pink by the dye (sign of chlorosis) and very short roots, if any at all.

Conclusions:

100 mg/l < ErC50 < 1000 mg/lEyC50: ca. 100 mg/l

Executive summary:

Method

The toxicity to aquatic plants of the substance has been conducted according to the OECD 221 and to the EU Method C.26 on Lemna Minor plants over a period of 7 days. The test was performed at nominal concentrations of 11.4, 114 and 1140 mg/l of the item, corresponding to 10, 100 and 1000 mg/l of the active ingredient.

 

Observation

With respect to growth rate inhibition for the endpoint frond numbers, the following effects as compared to the untreated controls were observed: 19 % at 100 mg/l and 75 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test. With respect to yield inhibition for the endpoint frond numbers, the following effects as compared to the untreated controls were observed: 18 % at 10 mg/l, 41 % at 100 mg/l and 92 % at 1000 mg/l. Moreover with respect to growth rate inhibition for the endpoint dry weight, the following effects as compared to the untreated controls were observed: 20 % at 100 mg/l and 67 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test. With respect to yield inhibition for the endpoint dry weight, the following effects as compared to the untreated controls were observed: 22 % at 10 mg/l, 44 % at 100 mg/l and 90 % at 1000 mg/l.

 

Results

Based on these data the median effect concentrations of the substance to Lemna minor with respect to growth rate (ErC50) for the endpoint frond numbers and dry weight were estimated to be 100–1000 mg/l nominal (NOErC = ca. 10 mg/l).

Moreover the median effect concentrations of the substance to Lemna minor with respect to yield (EyC50) for the endpoint frond numbers and dry weight were estimated to be about 100 mg/l nominal concentration (NOEyC < 10 mg/l).

Description of key information

100 mg/l < ErC50 < 1000 mg/l
EyC50: ca. 100 mg/l

Key value for chemical safety assessment

EC50 for freshwater plants:

100 mg/L

EC10 or NOEC for freshwater plants:

10 mg/L

Additional information

The inhibitory effects based on the average specific growth rate and the yield (absolute increase in plant size) to the duckweed Lemna minor was

investigated over a period of 7 days.

The test was performed at nominal concentrations of 11.4, 114 and 1140 mg/l of test substance, corresponding to 10, 100 and 1000 mg/l of the active ingredient (AI).

No chemical analysis of the test concentrations was conducted. The determination of the effect concentrations was based on the nominal concentrations of the active ingredient assuming the test item to be stable in medium for the whole test period.

For the endpoint frond number and with respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 19 % at 100 mg/l and 75 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test.

For the endpoint frond number and with respect to yield inhibition, the following effects as compared to the untreated controls were observed: 18 % at 10 mg/l, 41 % at 100 mg/l and 92 % at 1000 mg/l.

Based on these data the median effect concentrations to Lemna minor with respect to growth rate (ErC50) and to yield (EyC50) for the endpoint frond

number was estimated to be 100–1000 and about 100 mg/l nominal concentration, respectively.

The no-observed-effect concentrations to Lemna minor with respect to growth rate (NOErC) and yield (NOEyC) for the endpoint frond number were 10

and <10 mg/l nominal concentration, respectively, as determined by Dunnett's test.

For the endpoint dry weight and with respect to growth rate inhibition, the following effects as compared to the untreated controls were observed: 20 % at 100 mg/l and 67 % at 1000 mg/l. No significant effects were observed at 10 mg/l, as determined by Dunnet’s test.

For the endpoint dry weight and with respect to yield inhibition, the following effects as compared to the untreated controls were observed: 22 % at 10 mg/l, 44 % at 100 mg/l and 90 % at 1000 mg/l.

Based on these data the median effect concentrations to Lemna minor with respect to growth rate (ErC50) and to yield (EyC50) for the endpoint dry

weight was estimated to be about 100 – 1000 and about 100 mg/l nominal concentration, respectively.

The no-observed-effect concentrations to Lemna minor with respect to growth rate (NOErC) and yield (NOEyC) for the endpoint dry weight were 10 and <10 mg/l nominal concentration, respectively, as determined by Dunnett's test.