Executive Summary
Zinc (Zn) is naturally distributed as minerals and other non-elemental forms in nature in the Earth’s crust. Zn
is emitted to the environment from a variety of natural and anthropogenic point and non-point (diffuse) sources,
and is an essential nutrient found in organisms. In the United States, the vast majority of Zn is used in metals
industries, with 85% of Zn used to galvanize metals for corrosion resistance. Only 3% of Zn is used for non-
metallic purposes, including as an ingredient in personal care products, such as sunscreen (ZnO) and
medicated shampoos (Zn pyrithione), as well as in batteries, a biocide in paints and coatings, rubber
vulcanization, pharmaceuticals, and other products. Zn has been measured in industrial wastewater and stack
emissions, as well as in natural sources, such as wildfires and native soil runoff. Zn is also commonly found in
food products and biological waste, given that it is an essential mineral. In urban environments, each of these
sources can contribute variable amounts of Zn, which may eventually reach surface waters. In some areas
across the U.S., Zn levels in watershed runoff and point-source effluents have been found to be elevated with
respect to background levels in rain or upstream surface water