The free zinc ion in solution is highly toxic to bacteria, plants, invertebrates, and even vertebrate fish.

[1][5] Following an oral intake of extremely high doses of zinc (where 300 mg Zn/d – 20 times the US RDA – is a "low intake" overdose[1]), nausea, vomiting, pain, cramps, and diarrhea may occur.

[7][8][9][10][11] A decrease in copper levels and hematological changes have been reported; however, those changes were completely reversed with the cessation of zinc intake.

[14] Zinc concentrations are typically quantified using instrumental methods such as atomic absorption, emission, or mass spectroscopies; X-ray fluorescence; electro-analytical techniques (e.g., stripping voltammetry); or neutron activation analysis.

Detection of zinc in urine samples requires extraction of the metals with a polydithiocarbamate resin prior to digestion and analysis (NIOSH 1984).