Sodium [3-hydroxy-4-[(1-hydroxy-5-sulpho-2-naphthyl)azo]naphthalene-1-sulphonato(4-)]chromate(1-)

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:

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:

no

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

100.03 mg of the test item was weighed and made up to 100 ml using 20X-AAP growth medium to make a stock concentration of 1 mg/ml. All the required test concentrations were prepared for 800 ml. From the stock solution, each required test concentration was prepared as follows: 800 µl, 1760 µl, 3872 µl, 8520 µl, 18744 µl and 41232 µl were taken and made up to 800 ml with 20X-AAP medium to obtain 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L concentrations respectively. For Control, 20X-AAP medium was used.

Test organisms (species):

Lemna gibba

Details on test organisms:

TEST ORGANISM
- Strain: Lemna gibba (Duckweed)
- Source (laboratory, culture collection): In-house culture, RCC Laboratories India Private Limited (Originally procured by Department of Plant Biology & Plant Biotechnology Madras Christian College, Chennai)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

7 d

Hardness:

no data available

Test temperature:

Temperature in test vessel (°C) Start of the test
Control : 23.5
Treatment : 23.5
End of the test
Control : 24.8-25.1
Treatment : 25.1-25.3

pH:

Medium pH range Start of the test
Control : 7.54
Treatment : 7.48
End of the test
Control : 8.69-8.72
Treatment : 8.72-8.75

Dissolved oxygen:

no data available

Salinity:

no data available

Conductivity:

no data available

Nominal and measured concentrations:

1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 ml Glass Beaker
- No. of organisms per vessel: 12 fronds (3 plants)
- No. of vessels per concentration (replicates): Main Experiment - 3 replicates for each concentration
- No. of vessels per control (replicates): Control - 6 Replicates.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: Start of the test

- Photoperiod: Continuous Light
- Light intensity and quality: 8460-8650 Lux

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

21.12 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

frond number

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

9.55 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

frond number

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

21.67 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Frond Dry Weight; Growth

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

8.69 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Frond Dry Weight; Yield

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

2.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Frond number and dry weight

Details on results:

None

Results with reference substance (positive control):

ErC50 of 3,5-Dichlorophenol based upon the frond numbers observed for a period of ‘7’ days for Lemna gibba was calculated as 4.30 mg/L with a lower confidence limit of 4.15 mg/L and the upper confidence limit of 4.46 mg/L.
EyC50 of 3,5-Dichlorophenol based upon the frond numbers observed for a period of ‘7’ days for Lemna gibba was calculated as 2.38 mg/L with a lower confidence limit of 2.29 mg/L and the upper confidence limit of 2.48 mg/L.
ErC50 of 3,5-Dichlorophenol based upon the frond dry weight observed for a period of ‘7’ days for Lemna gibba was calculated as 3.02 mg/L with a lower confidence limit of 2.89 mg/L and the upper confidence limit of 3.16 mg/L.
EyC50 of 3,5-Dichlorophenol based upon the frond dry weight observed for a period of ‘7’ days for Lemna gibba was calculated as 1.53 mg/L with a lower confidence limit of 1.46 mg/L and the upper confidence limit of 1.59 mg/L.

Reported statistics and error estimates:

Mean coefficient of variation of average specific growth rate in replicate control and treated cultures were calculated. No analysis was done as the study is concluded with the Limit Test.

Validity criteria fulfilled:

yes

Conclusions:

ErC50 of FAT 20290/E TE based upon the frond numbers observed for a period of ‘7’ days for Lemna gibba was found to be 21.12 mg/L.

Executive summary:

Lemna gibba (Duckweed) were exposed to the test item (FAT 20290/C TE) at different test concentrations viz 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L. Initially on day ‘0’, 12 fronds were inoculated in beaker containing 200 ml of test medium (20X-AAP medium). Three replicates for each test concentration and six replicates for control were maintained. The test item was formulated in 20X-AAP medium. Prior to exposure, Lemna gibba was pre-cultured in the 20X-AAP medium for period of ‘8’ days and the pre-culture was found healthy. After exposure, Lemna gibba was observed for frond count on days ‘3’, ‘5’ and ‘7’. Dry weight of the fronds were recorded at start (pre-culture representative samples) and at the end of the test. Fronds were observed for their appearance on days ‘3’, ‘5’ and ‘7’. All fronds were found normal and healthy in all replicates of control and test concentrations except 51.54 mg/L where necrosis was observed on day 5 and in addition to necrosis, root filaments were turned blue in 10.65, 23.43 and 51.54 mg/L concentrations on day 7. The doubling time (T_d) of frond number in the control group was calculated as 1.62 day^-1.

Frond Numbers:

From the average specific growth rate recorded with the different test concentrations viz 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the test concentration that inhibited 50% growth (E_rC₅₀) was calculated as 21.12 mg/L with upper confidence limit of 22.14 mg/L and lower confidence limit of 20.14 mg/L. The percent inhibition on the average specific growth rate on day ‘7’ for the test concentrations of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, was calculated as 0.12, 0.11, 8.33, 34.62, 46.54 and 80.82 % respectively. From the yield recorded with the test concentrations, 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the concentration that inhibited 50% yield (E_yC₅₀) was calculated as 9.55 mg/L with upper confidence limit of 9.92 mg/L and lower confidence limit of 9.19 mg/L. The percent inhibition on the yield on day ‘7’ for the test concentrations of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, was calculated as 036, 0.36, 23.23, 67.95, 79.17 and 95.92 % respectively. The NOEC was calculated as 2.2 mg/L and LOEC was calculated as 4.84 mg/L.

Frond Dry Weight:

From the average specific growth rate recorded with the test concentrations, 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the concentration that inhibited 50% growth (E_rC₅₀) was calculated as 21.67 mg/L with upper confidence limit of 22.80 mg/L and lower confidence limit of 20.59 mg/L. The percent inhibition on the average growth rate on day ‘7’ for the concentration of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L was calculated as 0.00, 0.43, 11.75, 35.04, 42.09 and 80.13 % respectively. From the yield recorded with the test concentrations, 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the concentration that inhibited 50% yield (E_yC₅₀) was calculated as 8.69 mg/L with upper confidence limit of 9.04 mg/L and lower confidence limit of 8.35 mg/L.

The percent inhibition on the yield on day ‘7’ for the test concentration of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, was calculated as 0.03, 1.44, 33.26, 70.94, 77.63 and 96.41 % respectively. The NOEC was calculated as 2.2 mg/L, while LOEC was 4.84 mg/L.

 

E_rC₅₀ of FAT 20290/E TE based upon the frond numbers observed for a period of ‘7’ days for Lemna gibba was found to be 21.12 mg/L.

E_yC₅₀ of FAT 20290/E TE based upon the frond numbers observed for a period of ‘7’ days for Lemna gibba was found to be 9.55 mg/L

E_rC₅₀ of FAT 20290/E TE based upon the frond dry weight observed for a period of ‘7’ days for Lemna gibba was found to be 21.67 mg/L

E_yC₅₀ of FAT 20290/E TE based upon the frond dry weight observed for a period of ‘7’ days for Lemna gibba was found to be 8.69 mg/L.

Description of key information

Lemna gibba (Duckweed) were exposed to the test item (FAT 20290/C TE) at different test concentrations viz 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L. Initially on day ‘0’, 12 fronds were inoculated in beaker containing 200 ml of test medium (20X-AAP medium). Three replicates for each test concentration and six replicates for control were maintained. The test item was formulated in 20X-AAP medium.

Prior to exposure, Lemna gibba was pre-cultured in the 20X-AAP medium for period of ‘8’ days and the pre-culture was found healthy.

After exposure, Lemna gibba was observed for frond count on days ‘3’, ‘5’ and ‘7’. Dry weight of the fronds were recorded at start (pre-culture representative samples) and at the end of the test.

Fronds were observed for their appearance on days ‘3’, ‘5’ and ‘7’. All fronds were found normal and healthy in all replicates of control and test concentrations except 51.54 mg/L where necrosis was observed on day 5 and in addition to necrosis, root filaments were turned blue in 10.65, 23.43 and 51.54 mg/L concentrations on day 7.

The doubling time (T_d) of frond number in the control group was calculated as 1.62 day^-1.

Frond Numbers:

From the average specific growth rate recorded with the different test concentrations viz 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the test concentration that inhibited 50% growth (E_rC₅₀) was calculated as 21.12 mg/L with upper confidence limit of 22.14 mg/L and lower confidence limit of 20.14 mg/L.

The percent inhibition on the average specific growth rate on day ‘7’ for the test concentrations of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, was calculated as 0.12, 0.11, 8.33, 34.62, 46.54 and 80.82 % respectively. From the yield recorded with the test concentrations, 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the concentration that inhibited 50% yield (E_yC₅₀) was calculated as 9.55 mg/L with upper confidence limit of 9.92 mg/L and lower confidence limit of 9.19 mg/L. The percent inhibition on the yield on day ‘7’ for the test concentrations of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, was calculated as 036, 0.36, 23.23, 67.95, 79.17 and 95.92 % respectively. The NOEC was calculated as 2.2 mg/L and LOEC was calculated as 4.84 mg/L.

Frond Dry Weight:

From the average specific growth rate recorded with the test concentrations, 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the concentration that inhibited 50% growth (E_rC₅₀) was calculated as 21.67 mg/L with upper confidence limit of 22.80 mg/L and lower confidence limit of 20.59 mg/L.

The percent inhibition on the average growth rate on day ‘7’ for the concentration of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L was calculated as 0.00, 0.43, 11.75, 35.04, 42.09 and 80.13 % respectively.

From the yield recorded with the test concentrations, 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, the concentration that inhibited 50% yield (E_yC₅₀) was calculated as 8.69 mg/L with upper confidence limit of 9.04 mg/L and lower confidence limit of 8.35 mg/L.

The percent inhibition on the yield on day ‘7’ for the test concentration of 1, 2.2, 4.84, 10.65, 23.43 and 51.54 mg/L, was calculated as 0.03, 1.44, 33.26, 70.94, 77.63 and 96.41 % respectively.

The NOEC was calculated as 2.2 mg/L, while LOEC was 4.84 mg/L.

 

E_rC₅₀of FAT 20290/E TE based upon the frond numbers observed for a period of ‘7’ days for Lemna gibba was found to be 21.12 mg/L.

E_yC₅₀of FAT 20290/E TE based upon the frond numbers observed for a period of ‘7’ days for Lemna gibba was found to be 9.55 mg/L

E_rC₅₀of FAT 20290/E TE based upon the frond dry weight observed for a period of ‘7’ days for Lemna gibba was found to be 21.67 mg/L

E_yC₅₀of FAT 20290/E TE based upon the frond dry weight observed for a period of ‘7’ days for Lemna gibba was found to be 8.69 mg/L.

Key value for chemical safety assessment

EC50 for freshwater plants:

21.12 mg/L

EC10 or NOEC for freshwater plants:

2.2 mg/L