Potassium trifluoroacetate

Toxicity to terrestrial plants

Description of key information

By analogy with TFANa, the lowest EC50 measured for shoot growth of mung bean is 5.7 mg/kg dw and the NOEC is 1 mg/kg dw.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

5.7 mg/kg soil dw

Long-term EC10, LC10 or NOEC for terrestrial plants:

1 mg/kg soil dw

Additional information

No data on potassium trifluoroacetate is available for this endpoint. However, two reliable key studies are available for sodium trifluoroacetate which is used in a read-across approach (See the endpoint study summary "Aquatic toxicity" for the read-across justification). The results expressed in TFANa is directly applied to TFAK in a worst case approach (i.e. the molecular weight of Na is lower than the molecular weight of K).

In the first study, the effect of sodium trifluoroacetate (TFANa) in soil on seed germination and early plant growth of Sunflower (Helianthus annuus) and Mung Bean (Phaseolus aureus) was determined according to the testing OECD 208 guideline. Nine seeds per pot, in four replicates were sown in soil containing nominal concentrations of 1, 10, 100 and 1000 mg sodium trifluoroacetate / kg (dry soil) plus a control. The soil used consisting, by volume, of 50% sifted sterilised Mendip loam and 50% Cornish grit. It contains Osmocote 17:11:11 Fast Start, fritted trace elements 253A and superphosphate. The test substance was mixed with silver sand and this mixture was incorporated into the soil to produce the growth medium.

14 days after sowing, there was a statistically significant decrease in the proportion of Sunflower seeds which had germinated and emerged at (and above) 10 mg/kg dry soil. Germination of Mung Bean was affected at 1000 mg/kg.

The EC50s for germination were as follows:

Sunflower : EC50, germination = 250 mg TFANa/kg

Mung Bean : EC50, germination = 770 mg TFANa/kg

At the end of the test, 28 days after the seeds were sown, the mean fresh weight of the Sunflower shoots (cropped at soil level) was significantly reduced at all concentrations tested (at and above 1 mg/kg). Growth of Mung Bean was significantly reduced at and above 10 mg/kg. Therefore :

Sunflower : No observed effect concentration (NOEC) < 1 mg TFANa/kg.

Mung Bean : No observed effect concentration (NOEC) = 1 mg TFANa/kg dry soil.

The calculated EC50s for growth, based on nominal concentrations were as follows:

Sunflower : EC50, Shoot growth = 12 mg TFANa/kg.

Mung Bean : EC50, Shoot growth = 5.7 mg TFANa/kg dry soil.

In the second study, the effect of TFANa in soil on seed germination and early plant growth of Wheat (Triticum aestivum) was determined. Wheat seeds were sown in soil containing nominal concentrations of 1, 10, 100 and 1000 mg sodium trifluoroacetate / kg (dry soil) plus two controls. There was a statistically significant decrease in the proportion of seeds which had germinated and emerged after 14 days at 1000 mg/kg dry soil. The EC50 for germination could not be calculated statistically but was approximately 1000 mg/kg. There was no effect on germination at concentrations up to and including 100 mg/kg but the seedlings were observed to be smaller than those in the controls at 100 mg/kg. At the end of the test, 28 days after the seeds were shown, the mean fresh weight of the seedling shoots (cropped at soil level) was significantly reduced at and above 10 mg/kg. The calculated EC50 for growth, based on nominal concentrations was as follows: EC50 growth = 12 mg TFANa/kg dry soil (= 10 mg TFA/kg dry soil).

There was no significant effect on shoot weight at 1 mg sodium trifluoroacetate / kg and therefore : NOEC = 1 mg TFANa/kg dry soil (= 0.83 mg TFA/kg dry soil).

By analogy, for potassium trifluoroacetate, the lowest EC50 measured for shoot growth of mung bean is 5.7 mg/kg dw and the NOEC is 1 mg/kg dw.