 Stamp sand may be hazardous to human health, since it contains trace amounts of harmful heavy metals (such as arsenic).As a result, land created from stamp sand may be poisonous to plant life, and can pollute nearby water as well.For example, aquatic life in the Keweenaw Waterway, near the Keweenaw copper mines of Michigan, has declined significantly near stamp sand deposits, while the waterway is reasonably healthy in other areas.