In some cases, other chemicals mixed with the active ingredient for formulating the pesticide product may cause the toxicity to differ from that of the active ingredient alone. Acute inhalation toxicity is measured by LC50. LC means Lethal Concentration. Concentration is used instead of dose because the amount of pesticide inhaled from the air is being measured. LC50 values are measured in milligrams per liter.
Liters are metric units of volume similar to a quart.
The lower the LC50 value, the more poisonous the pesticide. Less is known about the chronic toxicity of pesticides than is known about their acute toxicity, not because it is of less importance, but because chronic toxicity is much more complex and subtle in how it presents itself. On the other hand, persons may be routinely exposed to small amounts of pesticides while mixing, loading, and applying pesticides or by working in fields after pesticides have been applied. There is no standard measure like the LD50 for chronic toxicity. How chronic toxicity of chemicals is studied depends upon the adverse effect being studied.