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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Based on comparison to the screening criteria, EDTA-Zn(NH4)2 is not B or vB. Based on comparison to the criteria in Annex XIII, the substance is also not T. EDTA (acid form) and its salts are not readily biodegradable according to OECD criteria. It was shown that under special conditions like adaptation or slightly alkaline pH, which is realistic under environmental surface water conditions, the biodegradability of EDTA is considerable enhanced. In acidic soils EDTA is expected to be oxidized by Mn(III/IV) hydroxides because the rate is greatly enhanced under acidic conditions. Therefore it can be concluded that EDTA is ultimately biodegradable under such environmental conditions. In addition, due to high water solubility and low adsorption, EDTA will eventually leach to ground- and surface waters and not accumulate in soil. Due to pH fluctuations in surface water, moderate substitution rates and the combined photodegradation and biodegradation, all EDTA salts will eventually disappear from surface water.

Less than 60% biodegradation was observed in an enhanced test in river water for an EDTA-Zn complex. The complex dissociates too  slowly under test conditions to consider this substance not persistent. At lower environmentally more realistic concentrations the dissociation of the complex is based on the stability constant theory expected to dissociate faster. The enhanced ready biodegradability test result is not suitable for evaluating the vP status of a substance.

EDTA-Zn(NH4)2 is not considered a PBT or vPvB substance.

Likely routes of exposure:

No data