Registration Dossier

Administrative data

Link to relevant study record(s)

Description of key information

It is considered highly likely that HEDTA will behave similarly to EDTA and on this basis it is expected to poorly absorb across the gastrointestinal tract and will be excreted  rapidly and largely unchanged. Dermal absorption is expected to be minimal.

Key value for chemical safety assessment

Bioaccumulation potential:
low bioaccumulation potential
Absorption rate - oral (%):
10
Absorption rate - dermal (%):
0.1

Additional information

There is limited information available on the toxicokinetics of HEDTA. The mode of action of the toxicity of these chemicals is considered to be due to their chelating capabilities and as such a higher chelating potential (and a large size) will reduce the potential for the compound to move across membranes and therefore reduce absorption and bioavailability of the compound. A review of the binding and ionisation potential of HEDTA and its structural analoge, EDTA, indicate that the behaviour of HEDTA and EDTA are similar (Dwibedy et al., 1999). The rate constants for the reaction of both chemicals with OH radicals indicate an increase with increase in pH, with an opposite trend observed in a small mid-region of pH (between 1 and 3).

There were no studies available on the absorption, metabolism, distribution or elimination (AMDE) for HEDTA. Toxicokinetic studies on humans and on rats indicate that the structural analogue, EDTA, is poorly absorbed across the gastrointestinal tract. The absorbed EDTA did not undergo any biotransformation and was rapidly excreted unchanged in urine. However it was noted that there is an increase in excretion of necessary ions such as Zn, Mn or Ca. It is considered that HEDTA will behave similarly to EDTA and on this basis it is expected to poorly absorb across the gastrointestinal tract and will be excreted rapidly and largely unchanged.

In a study on young, healthy, male volunteers Foreman etal (1954) investigated the dermal absorption of CaNa2 -EDTA. 3 mg of a mixture of14C labelled and unlabeled substance was prepared in a water soluble base which was applied over an area of 100 cm2 for 24 hours under occlusive conditions. The maximum activity in the urine was 0.001% of the administered dose.