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Since no studies investigating the terrestrial toxicity of trisodium hydrogen EDTA (CAS 150-38-9) are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read-across to structurally related EDTA species was conducted.

Edetic acid (EDTA) is mainly produced industrially and used as acid (H4-EDTA) and different sodium salts (mainly Na4-EDTA but also Na2- and Na3-EDTA). In lower amounts, other salts or metal complexes are produced (European Union, 2004 and 2004a). Each substance has the identical backbone structure which is substituted with four carboxylic groups resulting in a similar chemical reactivity. If edetic acid as well as the different salts are released to the environment the same ionic species are formed. The anionic form of EDTA is strongly capable to complex metal cations present in the environment to form stable chelate complexes (e.g. Fe3+, Co2+, Ni2+).

Based on the comparable chemistry of EDTA and its different salts the different substances are highly likely to share the same environmental behavior and toxicity. The cations of the salts (e.g. Na+, Ca2+) are not expected to contribute to the overall toxicity profile. Thus, a read-across from edetic acid as well as different salts to predict the hazard of trisodium hydrogen EDTA is considered justified. This approach is in line with the EU Risk Assessment report for EDTA and Na4-EDTA (European Union, 2004 and 2004a). A detailed justification on read-across is attached in IUCLID Section 13.

The acute toxicity of Edetic acid (CAS 60-00-4) to earthworms was determined in an experimental study comparable to OECD 207. After 14 d a LC50 of 158 mg/kg dry weight soil was derived (Edwards et al., 2009).

An additional study investigated the effects of EDTA to terrestrial plants. According to Evangelou et al. (2006) disodium dihydrogen EDTA (CAS 139-33-3) showed adverse effects on growth of Nicotiana tabacum after 21 d of exposure. However, the dry weight of plants strongly decreased at a concentration of 1.25 mmol/kg. Thus, the next lower concentration might be considered as NOEC value (0.25 mmol/kg equivalent to 84 mg/kg soil).

In conclusion trisodium hydrogen EDTA (CAS 150-38-9) is considered to have effects on terrestrial organisms.