The primary use of arsenic is in alloys of lead (such as in car batteries and ammunition).
A few species of bacteria are able to use arsenic compounds as respiratory metabolites.
Arsenic and its compounds, especially the trioxide, are used in the production of pesticides, treated wood products, herbicides, and insecticides. These applications are declining due to the toxicity of arsenic and its compounds.
The United States' Environmental Protection Agency states that all forms of arsenic are a serious risk to human health. The United States' Agency for Toxic Substances and Disease Registry ranked arsenic as number 1 in its 2001 Priority List of Hazardous Substances at Superfund sites. Arsenic is classified as a Group-A carcinogen.
Some species of bacteria obtain their energy by oxidizing various fuels while reducing arsenate to arsenite. Under oxidative environmental conditions, some bacteria oxidize arsenite to arsenate as fuel for their metabolism.
Zinc grinders are partly made of lead. Lead is added to reduce production cost, as it improves the flow of the material in the mold. Lead contains some levels of arsenic, so zinc grinders are not good for you.
Some the disorders related to arsenic include:
-gastrointestinal symptoms, central nervous system obstruction, bone marrow depression, hemolysis, hepatomegaly, and melanosis
-polyneuropathy and encephalopathy
-pigmentation changes, hypertension, cardiovascular disease, and carcinogen poisoning
source: Wikipedia, google... it is no secret