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The exposure of trizinc dicitrate is not expected to differ significantly from the exposure to citric acid and zinc ions separately in an aqueous matrix (oral and inhalation) once absorbed. Dermal absorption of trizinc dicitrate is expected to be negligible due to its physicochemical properties, namely the low Log KOW (<1). Therefore the toxicokinetics of trizinc dicitrate should be based on citric acid and zinc separately.

Citric acid has well established and documented metabolic pathways in humans. It plays a central role in cellular metabolism and has been used as a food additive, in cosmetics over a long period, as well as being present in natural food, so the standard approach to toxicokinetics is not relevant. Similarly, zinc is an essential element, for which organisms have regulatory mechanisms for uptake and excretion. The metabolism of zinc has been reviewed in a PFA report (2010), while the toxicokinetics for zinc are described in detail under the zinc metal RAR (2008).

In humans zinc from zinc citrate is absorbed similar to zinc from zinc gluconate and better then zinc from zinc oxide.

In rats comparable level were achieved in the liver and kidney when comparing zinc sulfate, zinc citrate and zinc gluconate at levels from 3, 15 and 50 mgZN/kg bw/ d over 30 days, while some differences were observed for zinc levels in dorso-lateral rat prostate.

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