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Toxicity to aquatic plants other than algae

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Reference
Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
key study
Study period:
25 Aug 2014 – 10 Sep 2014
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 (incl. QA statement)
Specific details on test material used for the study:
Test material: FAT 36034/W
Batch no.: Q30450ADZX
Appearance/color: Solid/red
Analytical monitoring:
yes
Details on sampling:
The test medium samples (100 mL in a 250 mL glass bottle) were stored deep-frozen (below -18 °C) until analysis.
Vehicle:
no
Details on test solutions:
Due to low water solubility of the test item a saturated solution was prepared by weighing 100 mg FAT 36034/W TE on a weighing scoop and transferring it to a volumetric flask. Test medium was added up to the bench mark (1 L). The solution was stirred for 48 hours in the dark. Undissolved test item was allowed to sediment and/or float for a period of 1 hour. Afterwards the stock solution was withdrawn from the middle of the preparation vessel by suction without transferring undissolved test item (according to OECD SERIES ON TESTING AND ASSESSMENT No. 23). Aliquots of the withdrawn phase were diluted with test medium to receive the lower test item concentrations.
Test organisms (species):
Lemna gibba
Details on test organisms:
The test organism was the aquatic plant duckweed, Lemna gibba G3 (Alismatales: Araceae). The plants used in this study were taken as aseptic clones from the cultivation of the testing facility. They were primarily cultured by Dr. Janet Slovin, Horticulture Crops Quality Laboratory, U.S. Department of Agriculture. BARC-West, Bldg. 050 HH-4, Beltsville, MD 20705, U.S.A.
The plants were cultured in appropriate glass beakers under continuous illumination with OSRAM light tubes (L30/32-930 and L30/W72-965), at 6500 - 7000 lux. The temperature was 24 +/- 2 °C. Before the test was started, plants were cultured under the same illumination and temperature conditions as those to be used for the toxicity test. Young, light-green plants of similar size and comprising 2 - 5 fronds were transferred onto fresh medium and cultured for +/- 3 weeks prior to testing, with two further transfers onto fresh medium before initiating the test.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
7 d
Test temperature:
22.8 - 24.2 degC
pH:
8.28 (std dev. 0.61)
Nominal and measured concentrations:
see table below
Details on test conditions:
Test procedure: semi-static test
Duration: 7 days
Temperature: 22.8 – 24.2 °C
pH-value of fresh solution:7.42 – 8.61
Light intensity (mean): ~ 7600 lux
Light tubes:OSRAM light tubes (L 30 W77 and L 30 W25)
Exposure to light: continuously
Test vessels: 250 mL glass beakers filled with 150 mL
Number of fronds: 12 per test vessel
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
2.77 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of frond number
Remarks on result:
other: -
Duration:
7 d
Dose descriptor:
EC20
Effect conc.:
2.9 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of frond number
Remarks on result:
other: -
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of frond number
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
0.626 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of frond number
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of frond number
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
2.95 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of frond number
Remarks on result:
other: -
Duration:
7 d
Dose descriptor:
EC20
Effect conc.:
> 3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of frond number
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of frond number
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
0.626 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of frond number
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of frond number
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
2.72 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield of dry weight
Remarks on result:
other: -
Duration:
7 d
Dose descriptor:
EC20
Effect conc.:
2.84 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of dry weight
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of dry weight
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
0.626 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of dry weight
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: yield of dry weight
Duration:
7 d
Dose descriptor:
EC10
Effect conc.:
2.84 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of dry weight
Remarks on result:
other: -
Duration:
7 d
Dose descriptor:
EC20
Effect conc.:
2.97 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of dry weight
Remarks on result:
other: -
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
> 3 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of dry weight
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
0.626 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other: growth rate of dry weight
Duration:
7 d
Dose descriptor:
LOEC
Effect conc.:
3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
other:
Reported statistics and error estimates:
The statistical evaluation for day 7 was performed for yield of frond numbers, growth rate of frond numbers, growth rate dry weight and yield of dry weight. A test for normality of the data was performed by calculating the Shapiro-Wilk’s statistic, a test for homogeneity of the data was performed according to Levene. The NOEC and LOEC were determined by using a multiple comparison method (Dunnett`s t-test). The calculation of EC10 and EC20 values for all parameters was done using probit analysis following Gompertz procedure. Negative values were set to zero. The calculation of EC50 values were not indicated since inhibition was below 50 %. The evaluation of data was performed by SAS® (2002-2010).

 

FAT 36034/W TE [mg/L loading rate]

Endpoint

EC102)

95 % confidence limit

EC202)

95 % confidence limit

EC50

95 % confidence limit

NOEC1)

LOEC1)

Yield of frond numbers

94.4

93.0-95.8

97.4

96.0-98.9

>100

-

31.3

100

Growth rate of frond numbers

98.8

96.4-101

>100

-

>100

-

Yield of dry weight

92.9

91.7-94.2

96.1

94.8-97.3

>100

-

Growth rate of dry weight

96.0

94.4-97.7

99.2

97.5-101

>100

-

1)following Dunnetts-t-test

2)Probit analysis following Gompertz distribution

Validity criteria fulfilled:
yes
Conclusions:
The nominal EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be >100 mg/L loading rate. Based on the geometric mean of the analysed concentration levels, the EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be >3.00 mg/L (actual).
Executive summary:

The toxicity potential of FAT 36034/W on growth of Lemna was studied aacording to OECD Guideline 221. Significant inhibitory effects were determined for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) at 100 mg/L loading rate and 3.00 mg/L (actual). The overall LOEC was determined to be 100 mg/L loading rate and 3.00 mg/L (actual).

The nominal EC10-value for yield of frond numbers is 94.4 mg/L loading rate, 92.9 mg/L loading rate for yield of dry weight and 96.0 mg/L loading rate for growth rate of dry weight. The nominal EC10-value for growth rate of frond numbers is 98.8 mg/L loading rate.

Based on the geometric mean of the analysed concentration levels, the EC10-value for yield of frond numbers is 2.77 mg/L, 2.72 mg/L for yield of dry weight and 2.84 mg/L for growth rate of dry weight. The actual EC10-value for growth rate of frond numbers is 2.95 mg/L.

The nominal EC20-value for yield of frond numbers is 97.4 mg/L loading rate, 96.1 mg/L loading rate for yield of dry weight and 99.2 mg/L loading rate for growth rate of dry weight. The nominal EC20-value for growth rate of frond numbers is >100 mg/L loading rate.

Based on the geometric mean of the analysed concentration levels, the EC20-value for yield of frond numbers is 2.90 mg/L, 2.84 mg/L for yield of dry weight and 2.97 mg/L for growth rate of dry weight. The actual EC20-value for growth rate of frond numbers is >3.00 mg/L.

The nominal EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be >100 mg/L loading rate.

Based on the geometric mean of the analysed concentration levels, the EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be  >3.00 mg/L (actual).

The test is valid as the doubling time of control frond numbers was calculated to be 40.2 h, corresponding to 1.675 days at day 7. This is less than the maximum allowable doubling time set in OECD guideline 221 (60 h, 2.5 days).

Toxicological endpoints for FAT 36034/W TE:        

 

FAT 36034/W TE [mg/L loading rate]

Endpoint

EC102)

EC202)

EC50

NOEC1)

LOEC1)

Yield of frond numbers

94.4

97.4

>100

31.3

100

Growth rate of frond numbers

98.8

>100

>100

Yield of dry weight

92.9

96.1

>100

Growth rate of dry weight

96.0

99.2

>100

 

FAT 36034/W TE [mg/L] actual*

Endpoint

EC102)

EC202)

EC50

NOEC1)

LOEC1)

Yield of frond numbers

2.77

2.90

>3.00

0.626

3.00

Growth rate of frond numbers

2.95

>3.00

>3.00

Yield of dry weight

2.72

2.84

>3.00

Growth rate of dry weight

2.84

2.97

>3.00

*based on geometric mean of each concentration level

1)following Dunnetts-t-test

2)Probit analysis following Gompertz distribution

Description of key information

The nominal EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be >100 mg/L loading rate. Based on the geometric mean of the analysed concentration levels, the EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be >3.00 mg/L (actual).

Key value for chemical safety assessment

EC50 for freshwater plants:
3 mg/L
EC10 or NOEC for freshwater plants:
2.95 mg/L

Additional information

The toxicity potential of FAT 36034/W on growth of Lemna was studied aacording to OECD Guideline 221. The nominal EC10-value for yield of frond numbers is 94.4 mg/L loading rate, 92.9 mg/L loading rate for yield of dry weight and 96.0 mg/L loading rate for growth rate of dry weight. The nominal EC10-value for growth rate of frond numbers is 98.8 mg/L loading rate. Based on the geometric mean of the analysed concentration levels, the EC10-value for yield of frond numbers is 2.77 mg/L, 2.72 mg/L for yield of dry weight and 2.84 mg/L for growth rate of dry weight. The actual EC10-value for growth r ate of frond numbers is 2.95 mg/L.


The nominal EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be >100 mg/L loading rate. Based on the geometric mean of the analysed concentration levels, the EC50-value for all parameters (yield and growth rate of frond numbers and yield and growth rate of dry weight) was determined to be >3.00 mg/L (actual).


The test is valid as the doubling time of control frond numbers was calculated to be 40.2 h, corresponding to 1.675 days at day 7. This is less than the maximum allowable doubling time set in OECD guideline 221 (60 h, 2.5 days).