diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

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:

23 - 31 Oct 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: OECD Draft-guideline, US-EPA Pesticide Assessment Guidelines J 123-2 and according to ASTM E 1415-91 guideline

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance was dissolved in nutrient medium. Acetone (p.a.) was used as an additional solvent to prepare the stock solutions.

Test organisms (species):

Lemna gibba

Details on test organisms:

Species: Lemna gibba G3
Supplier: AgrEvo USA Company, AgrEvo Research Center, Environmental Biology Department, 703 NOR-AM Road, PO Box 538, Pikeville, NC 27863
Original supplier: Plant Hormone Laboratory, United States Department of Agriculture (USDA), Beltsville, MD

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Reference substance (positive control):

yes

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

> 11.9 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

2.32 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

growth rate

Findings:

Water quality parameters such as pH, oxygen content and temperature were determined to be within the

acceptable limits. Chemical analysis of all fresh and old testing solutions revealed test item concentrations below

80 % nominal. Since also the TWA measured figures were below 80% nominal, the TWA concentrations of AE

F107892 + AE F113225 were used to report the results (see table below).

Concentration (mg/L)	Nominal	3.2	5.6	10.0	18.0	32.0
AE F107892	7 d TWA	1.07	1.67	4.41	4.91	8.54
AE F107892+ AE F113225	7 d TWA	1.52	2.32	6.22	6.69	11.99
AE F113225 *	7 d TWA	0.42	0.60	1.68	1.55	3.19
* Calculation: difference of AE F107892 + 113225 and AE F107892 corrected by molecular weight ratio AE F113225 (345.2) / 107892 (373.26)

Biological findings: A significant inhibition of biomass increase (dry weight) was observed at measured

concentrations > 6.22 mg/L resulting in NOEC of 2.32 mg/L test item. No morphological intoxication

symptoms were observed at any treatment level.

Conclusion:

In a static renewal exposure system for 7 days, AE F107892 had no phytotoxicity effects on the aquatic plant

Lemna gibba at concentrations up to and including 2 320 μg/L. Therefore, the NOEC was 2 320 μg/L and the 7-

d EC50 value was > 11 990 μg/L test item based on TWA measured concentrations.

Description of key information

EC50 (7 d) > 11.99 mg/L with Lemna gibba (OECD draft guideline, 1998)
NOEC (7 d) = 2.32 mg/L with Lemna gibba (OECD draft guideline, 1998)

Additional information

A duckweed (Lemna gibba) growth inhibition test according to OECD draft guideline (1998) and US EPA J-123-2 is available. In the static renewal 7 days exposure system the test item had no phytotoxicity effects at concentrations up to and including 2.32 mg/L. Therefore, the NOEC was 2.32 mg/L and the 7-d EC50 value was > 11.99 mg/L test item based on TWA measured concentrations.