pymetrozine (ISO); (E)-4,5-dihydro-6-methyl-4-(3-pyridylmethyleneamino)-1,2,4-triazin-3(2H)-one

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:

supporting study

Study period:

25 May 1995 to 08 Jun 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other:

Version / remarks:

FIFRA Guideline No. 123-2

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Lemna gibba

Test type:

static

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

> 109 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

frond number

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

49.2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

frond number

Nominal test concentrations were 8.5 to 130 mg/L; the initial measured concentrations amounted to 71-84 % of the nominal concentrations (between 6.1 and 109 mg/L) but showed a strong decrease to below the analytical detection limit (5.1 mg/L) after 14 days, indicating some type of absorption or degradation.

The duckweed population in the control vessels grew well, increasing from an average of 12 fronds per vessel to an average of 217 fronds per vessel after 14 days. The EC25, EC50 and NOEC values were 68, > 109 and 49 mg/L, respectively. They are determined on basis of effects on the frond production after 14 days exposure and refer to initial measured test concentrations. The NOEC is based on the number of non-chlorotic fronds.

Analytical results:

Nominal concentration (mg/L)	Measured concentration (mg/L)
	Day 0	Day 14
0 (control)	< 5.06 (LOD)	< 5.06 (LOD)
8.5	6.06	< 5.06 (LOD)
17	12.2	< 5.06 (LOD)
33	20.6 28.0	< 5.06 (LOD)
65	49.2	< 5.06 (LOD)
130	109	< 5.06 (LOD)

Validity criteria fulfilled:

yes

Conclusions:

The duckweed population in the control vessels grew well, increasing from an average of 12 fronds per vessel to an average of 217 fronds per vessel after 14 days. The EC25, EC50 and NOEC values were 68, > 109 and 49 mg/L, respectively.

Executive summary:

The effect of the test substance on the growth of the duckweed Lemna gibba was studied for 14 days under static conditions at pH 5 and continous illumination. The study was performed according to the FIFRA Guideline No. 123-2 guideline. Nominal test concentrations were 8.5 to 130 mg/L; the initial measured concentrations amounted to 71-84 % of the nominal concentrations (between 6.1 and 109 mg/L) but showed a strong decrease to below the analytical detection limit (5.1 mg/L) after 14 days, indicating some type of absorption or degradation. The EC25, EC50 and NOEC values were 68, > 109 and 49 mg/L, respectively. They are determined on basis of effects on the frond production after 14 days exposure and refer to initial measured test concentrations. The NOEC is based on the number of non-chlorotic fronds.

Description of key information

The 14-d EC50 and NOEC are > 109and 49.2 mg/L, respectively, in duckweed, FIFRA Guideline No. 123-2, Boeri 1995.

Information on this endpoint is not part of Annex VIII data requirements; all included studies are marked as supporting information and considered in the CSA.