Disodium [[N,N'-ethylenebis[N-(carboxymethyl)glycinato]](4-)-N,N',O,O',ON,ON']cuprate(2-)

Toxicity to terrestrial plants

Description of key information

Three studies with EDTA salts or complexes have been performed, examining different end-points (vegatative vigour and seedling emergence) in different plant species. In the 21d veg vigour study (Evangelou et al., 2006) a true NOEC could be established, while in the 14d seedling emergence test (Geebelen et al., 2002) no effect was observed at the highest tested dose. Recalculation of the NOEC from EDTA-Na2H2 to EDTA-CuNa2 will give a NOEC of 99.2 mg/kg soil dw.

The study from Fiebig (2019) which was performed with EDTA-CuK2 according to OECD TG 208 gave a lowest EC50 of 225 mg test substance/kg dw for the number of emerged seedlings of soybean. The batch of EDTA-CuK2 had an active ingredient content of 92%. The EC50 based on active ingredient is then 207 mg a.i./kg dw.

This result is recalculated to EDTA-CuNa2 complex (see chapter 13 for justification) using the ratio of the MW's (of 397.3/430) resulting in an EC50 of 191.3 mg EDTA-CuNa2/kg dw. The study from Fiebig will be based on the higher quality be used for the terrestrial hazard assessment.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

191.3 mg/kg soil dw

Additional information

The hazard assessment of EDTA-CuNa2 reveals neither a need to classify the substance as dangerous to the environment, nor is it a PBT or vPvB substance. The substance is expected to have a low potential for adsorption based on its ionic structure under environmental relevant pH conditions and its low log Kow , the low log Kow also indicates that the substance will not be bioaccumulative. There are no further indications that the substance may be hazardous to the environment.

Study summary

The phytotoxicity of"EDTA-CuK2 to three terrestrial plant species was determined according to OECD 208 (July 2006)in a seedling emergence and seedling growth tests over a period of 21 days.

 

The test systems comprised one monocotyledon (oats, Poaceae) and two dicotyledons (rape, Brassicaceae; soybean, Fabaceae). 

The test was conducted with the test concentrations of 1000 - 400 - 160 - 64 - 25.6 mg/kg soil dry weight (DW) (factor 2.5).

 The test item dissolves well in water and was incorporated into the soil in which the seeds were sown. The test containers were bottom watered with nutrient solution as needed.

 

The stock solution was sampled prior to application and subsequently analytically verified. The measured concentration of EDTA-CuK2was 101 % indicating the correct preparation of the stock solution.

 

Potential toxic effects of the test item were assessed on day 7, 14 and 21 by visual observations (number of emerged seedlings and phytotoxic effects) and at test end by shoot height and shoot fresh weight determination.

 

The results of the control for all plant species met the required validity criteria. Therefore, the test is considered to be valid.

 

Table1:          Shoot Height: NOEC, LOEC, EC₂₅- and EC₅₀-Values with Confidence Range (p)

Species

NOEC [mg/kg DW]

LOEC [mg/kg DW]

EC25 [mg/kg DW]

p = 95% [mg/kg DW]

EC50 [mg/kg DW]

p = 95% [mg/kg DW]

Oats

400

1000

> 1000

̶

> 1000

̶

Rape

160

400

490

364 - 626

> 1000

̶

Soybean

≥ 400^#

> 400^#

> 400^#

̶

> 400^#

̶

Table2:          Shoot Fresh Weight: NOEC, LOEC, EC₂₅- and EC₅₀-Values with Confidence Range (p)

Species	NOEC [mg/kg DW]	LOEC [mg/kg DW]	EC25 [mg/kg DW]	p = 95% [mg/kg DW]	EC50 [mg/kg DW]	p = 95% [mg/kg DW]
Oats	400	1000	964	746 - > 1000	> 1000	̶
Rape	160	400	230	182 - 300	403	317 - 500
Soybean	≥ 400^#	> 400^#	279	120 - > 400^#	> 400

EC25 [mg/kg DW]

p = 95% [mg/kg DW]

EC50 [mg/kg DW]

p = 95% [mg/kg DW]

Oats

400

1000

> 1000

̶

> 1000

̶

Rape

160

400

490

364 - 626

> 1000

̶

Soybean

≥ 400^#

> 400^#

> 400^#

̶

> 400^#

̶

Table2:          Shoot Fresh Weight: NOEC, LOEC, EC₂₅- and EC₅₀-Values with Confidence Range (p)

Species	NOEC [mg/kg DW]	LOEC [mg/kg DW]	EC25 [mg/kg DW]	p = 95% [mg/kg DW]	EC50 [mg/kg DW]	p = 95% [mg/kg DW]
Oats	400	1000	964	746 - > 1000	> 1000	̶
Rape	160	400	230	182 - 300	403	317 - 500
Soybean	≥ 400^#	> 400^#	279	120 - > 400^#	> 400

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