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EC number: 267-956-0
CAS number: 67953-76-8
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).
The acid, sodium and potassium salts in the HEDP category are freely
soluble in water and, therefore, the HEDP anion is fully dissociated
from its sodium or potassium cations when in solution. Under any given
conditions, the degree of ionisation of the HEDP species is determined
by the pH of the solution. At a specific pH, the degree of ionisation is
the same regardless of whether the starting material was HEDP-H, HEDP
(1-2Na), HEDP (2-3Na), HEDP-4Na, HEDP-xK or another salt of HEDP.
Therefore, when a salt of HEDP is introduced into test media or the
environment, the following is present (separately):
In this context, for the purpose of this assessment, read-across of data
within the HEDP Category is considered to be valid.
In accordance with Column 2 of REACH Annex IX, 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-xK 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 (no effects observed
to Eisenia fetida or Avena sativa after 14-days exposure,
up to concentrations of 1000 mg active acid/kg soil dry weight). 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.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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