Modeling zinc regulation in small mammals

Area of Science:

• Environmental toxicology
• Mammalian ecotoxicology
• Biogeochemical cycles

Background:

• Global zinc discharges contaminate terrestrial and aquatic ecosystems.
• Embanked floodplains, like those of the lower Rhine River, accumulate significant heavy metals, including zinc.
• Potential risks to wildlife from zinc bioaccumulation necessitate risk assessment, but toxicokinetic models are lacking for mammals.

Purpose of the Study:

• To develop a zinc toxicokinetic model for small mammals.
• To predict internal zinc concentrations based on dietary zinc intake.
• To aid in risk assessment for wildlife exposed to environmental zinc.

Main Methods:

• Developed a zinc kinetics model using adapted Michaelis-Menten equations for absorption and excretion.
• Parameterized the model with published experimental data on zinc metabolism.
• Validated the model using field data from four small mammal species in a Rhine River floodplain.

Main Results:

• The model accurately predicts internal zinc concentrations within a dietary range of 3 to 104 mg/kg dry weight, indicating regulation.
• Model predictions showed variations from field measurements by a factor of 1.6 for the common shrew and 1.7 for the common vole.
• Model calibration was limited outside the tested dietary zinc range due to insufficient data.

Conclusions:

• The developed zinc kinetics model provides a valuable tool for predicting internal zinc levels in small mammals.
• The model supports risk assessment for wildlife in zinc-contaminated environments.
• Further research is needed to expand the model's applicability beyond the current dietary zinc range and for a wider species.