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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

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

EDTA is not readily biodegradable according to OECD criteria. It was shown that with natural river water as inoculum, in standard OECD 301D tests, EDTA complexes with a stability constant lower than 10E14 like EDTA-Na4, EDTA-CaNa2, EDTA-MgNa2 etc. less than 60% biodegradation was observed after 28 days indicating that these substances should be not classified as readily biodegradable but in these tests > 60% biodegradation was observed after 60 days in the prolonged (enhanced) tests indicating that these complexes, having stability constants < 10E14, are not persistent. This stability constant threshold of 10E14 will be dependent on the concentration balance between the starting complex and free metal ions (alkali and alkaline earth metals). The lower the starting concentration of the EDTA-metal complex the higher this stability constant threshold for biodegradation. In general it can be assumed that complexes with a stability constant >= 10E14 like EDTA-ZnX complexes (where X stands for K2, Na2 or (NH4)2) should be considered "Completely and inherently biodegradable". The dissociation rates are however considered too low to allow classification as not persistent.

Based on the estimated log Kow (<3) and available BCF study in fish with radiolabeled EDTA (BCF range 1.1-1.8) it can be concluded there is low potential for bioaccumulation for EDTA-ZnNa2.

All chronic aquatox endpoints > 10 mg/L and additional low toxicity to terrestrial organisms.

EDTA-ZnNa2 is not considered a PBT or vPvB substance.

Likely routes of exposure:

No data