Isopropalin
Isopropalin is a herbicide. Introduced in 1969, it is a preëmergent selective dinitroaniline to control annual grasses and broadleaf weeds. Brought by DowElanco in 1972 to the US and Australia, it is now considered obsolete. In 1974, American farmers used of isopropalin.
Paarlan was a 69% isopropalin emulsifiable concentrate approved for use on tobacco. It required soil incorporation due to low solubility, ultraviolet light degradation and high volatilisation, and it may have been registered for white potatoes and tomatoes. Dow marketed Paarlan to southern culture, with a video advert claiming it "is just as much a part of tobacco country as ham and biscuits are part of breakfast."
Rats fed diets with large amounts of isopropalin had reduced hemoglobin concentrations, lowered hematocrits, and altered organ weights at the higher doses tested.
Isopropalin is the most persistent dinitroaniline herbicide in soil, with a field halflife of nearly 10 months, though only 6 months in the greenhouse test. It is one of the least phytotoxic to sorghum, though in weed-control tests had roughly middle of the pack phytotoxicity to weeds.