Simazine registrations

Simazine was submitted to federal, state, and other research institutions for experimental use in corn and to European authorities for testing. Simazine received its first registration in Switzerland in 1956. 

The trade name Princep was introduced in 1969, and the US registration for technical simazine was granted in 1974. This allowed the technical material to be used by other companies to formulate and market products containing simazine. A water-based flowable liquid also was registered in 1974 and soon became the leading formulation of simazine sold in the United States. 

With the approval of simazine in 1957 by the USFDA, USDA, and USEPA, the basis and procedures for successful introductions of other chlorotriazines were established. Although additional development work was necessary for approval and registration of the subsequent chlorotriazines, the procedures to optimize the production, formulation, and directions for use and the protocols to analyze and understand metabolism and toxicology remained similar. Approval for the first commercial uses of simazine and atrazine in various countries are given in Tables 3.3 and 3.4, respectively. 

Simazine was among the first herbicides registered for use in Florida citrus in 1962 and was recommended by the University of Florida as an excellent weed control tool for citrus (Kretchman and McCown, 1962). This early registration of simazine was for the control of annual weeds, while today s registration includes broadleaf weeds, annual vines, and annual grasses (Singh and Tucker, 1987). 

Worldwide there have been a total of 20 commercialized triazine herbicides. Of the 20 triazines, 7 are currently registered for land use within the United States ametryn, atrazine, metribuzin, prometryn, simazine, terbutryn, and prometon. For purposes of this discussion, only dietary estimates for the 5 most widely used domestic triazines are presented since the USEPA revoked cyanazine tolerances in 2004, prometon is not used for food crops and terbutryn has very limited use. Additionally, propazine was used under USEPA Section 18 registrations in the 1990s, and in 2007 was registered for weed control in sorghum (USEPA, 2007). 

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