Making good use of arsenic's toxicity to control pests and diseases

The toxicity of arsenic compounds has meant that uncontrolled exposure to them raises issues of industrial health and safety and environmental contamination. Deployed under controlled conditions, however, arsenic compounds have been used to improve human health through control of syphilis (Salvarsan) and general well-being (Fowler's solution) and, more recently, for treatment of some cancers. Animal health has been improved, too, by the use of arsenicals to treat parasites, crops have been protected from insect pests, and biological materials in museum and other collections have been preserved from insect and fungal attack. In some case, widespread dispersion of arsenical biocides has left a legacy of environmental contamination.