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Toxicity to terrestrial plants

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Endpoint:
toxicity to terrestrial plants: short-term (with study design considered suitable for long-term assessment)
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study scientifically not necessary / other information available
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other:

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Two reliability 4 studies are available for HEDP (2-3Na) that indicate low toxicity to plants. Minimum toxicity was observed in a range of weeds and crops at application rates ranging from 3 -30 kg/ha and 1 -100 mg/L for tomato, cucumber and radish plants (Gledhill and Feijtel, 1992). A 14-day NOEC value of 960 mg active acid/kg soil dry weight was determined for the effects of HEDP (2-3Na) on Avena sativa (Henkel, 1984).

In accordance with Column 2 of REACH Annex IX and Annex X, there is no need to further investigate the effects of this substance in terrestrial plant study because, as indicated in REACH guidance R7c Section R.7.11.6 (ECHA 2017), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that the Risk Characterisation Ratio is below 1, therefore the risk is already adequately controlled and further testing is not justifiable.   The substance is involatile and highly adsorbing and low toxicity was observed in short and long-term aquatic tests, and there is no reason to expect effects in the terrestrial compartment that were not expressed in the aquatic compartment.   Based on the long-term aquatic data set, the most sensitive trophic level is invertebrates. Due to its high adsorption and low toxicity to aquatic organisms, HEDP (2-3Na) was assigned to soil hazard category 3 (R.7c Section R.7.11.6, ECHA 2017) and a screening assessment was conducted, based on the equilibrium partitioning method (PEC * 10 / PNECscreen). In accordance with Table R.7.11 -2 of R.7c Section R.7.11.6, confirmatory testing for long-term toxicity to terrestrial organisms has been carried out with one trophic level, earthworms (consumers). PNECsoil has been derived using both the equilibrium partitioning method and measured terrestrial ecotoxicity data and the most conservative value (PNECsoil based on measured terrestrial ecotoxicity data) has been used for PNECsoil. As the terrestrial RCRs based on this PNEC are < 1, no further toxicity testing of soil organisms is currently considered to be necessary. Additionally, supporting data from terrestrial plants and short-term earthworm studies indicate low toxicity (14-day LC50and NOEC values of >960 and ≥960 mg active acid/kg soil dry weight for Eisenia fetida and Avena sativa, respectively). The phosphonate ligand binds strongly and irreversibly to various minerals present in soil and so bioavailability to soil organisms is extremely limited. Details on how the PNEC and the risk characterisation ratio have been derived can be found in IUCLID Section 6.0 and Chapters 9 and 10 of the Chemical Safety Report, respectively.