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EC number: 205-758-8
CAS number: 150-38-9
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). Other salts or metal complexes are produced in lower
amounts (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 Na3-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.
For the hazard assessment of trisodium hydrogen EDTA (CAS
150-38-9) several studies performed with EDTA, Na4-EDTA, Na2H2-EDTA are
available. All experimental data indicate low toxicity to aquatic
organisms. The observed effects are mainly related to reduced pH in the
test medium at very high concentrations and/or complexation of
micronutrients which are essential for health of test species.
Complexation of nutrients is especially problematic in algae tests since
the demand of nutrients by the algae is very high during exponential
The acute toxicity of EDTA to fish highly depends on water
hardness, pH and metal speciation (European Union, 2004 and 2004a). The
toxicity of EDTA complexes to bluegill sunfish was determined in a key
study performed by Batchelder et al. (1980), taking into account water
hardness and pH. The revealed LC50 values are in a range of 41 mg/L to
1592 mg/L. Consequently, and in line with the EU Risk Assessment (2004),
the LC50 of EDTA is estimated to be higher than 100 mg/L, due to the
fact that this predicted value represents the lowest LC50 at acceptable
pH in a study performed in natural non-synthetic water.
Tests on the acute toxicity with Daphnia magna resulted in an EC50 (48
h) of 140 mg/L detected in a non-GLP study according to DIN 38412 with
The results of four studies on freshwater green algae indicate that the
predicted EC50 (72 h) for EDTA (acid form) and its salts are > 60 mg/L
(measured) and can be estimated to be higher than 300 mg/L in studies
where the complexation of nutrients was limited to a minimum.
The long-term toxicity of Na2H2-EDTA on Daphnia magna was measured
in a reproduction test according to OECD 211 (GLP). After 21 days of
exposure a NOEC of 25 mg/L based on reproduction was observed.
The toxicity of Na2H2-EDTA on microorganisms was tested in an
activated sludge respiration inhibition test according to OECD guideline
209 (van Ginkel & Stroo, 2000). The EC50 (30 min) was measured to be >
500 mg/L. For Na4-EDTA a similar low toxicity on activated sludge was
measured in a respiration inhibition test according to ISO 8192. A test
concentration of 1000 mg/L caused no effects on the respiration rate of
microorganisms resulting in an EC10 (30 min) > 1000 mg/L.
In conclusion the ionic species of EDTA are of low toxicity to
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