High Quality Content by WIKIPEDIA articles! Because of safety concerns, some pesticides are not available to the general public in the United States. The "Restricted Use" classification restricts a product, or its uses, to use by a certificated pesticide applicator or under the direct supervision of a certified applicator. Certification programs are administered by the individual states and the requirements vary from state to state. Pesticides are classified as "restricted use" for a variety of reasons: Accident history Potential for or history of groundwater contamination Acute toxicity to humans Application scenario likely to be hazardous; e.g. fumigants. Toxicity to vulnerable nontarget plants or animals, particularly away from the site of application: fish, migrant birds Carcinogenic or mutagenic product Atrazine is the most widely used restricted-use herbicide.