Lewis Creek Farm
What is LD50?
inverse measure of pesticide toxicity
is the standard measure of pesticide toxicity. The higher the number, the less
the pesticide. Hereís why: All pesticides, even those approved for organic production,
are tested in the following manner. The pesticide is fed to mammalian test subjects
(probably lab rats) in increasing doses, until half of the subjects die. This dose
is the lethal dose that killed 50% of the mammalian population, or LD50.
It is measured in milligrams of pesticide per kilogram of body weight, or mg/kg.
So the higher the LD50 the larger
the dose it took to kill 50% of the mammalian population and therefore the less toxic
Note from the LD50s
that even the pesticides approved for organic production are toxic at some level,
except for Surround, which is plain old clay. Note as well that some of the synthetic
chemicals we use are less toxic than some of the pesticides approved for organic
production. For example Cupric Hydroxide (approved for organic production) has a
lower LD50 (that means itís more
toxic) than either Malathion or Linuron, which are not approved for organic production.
interesting fact about pyrethrin and synthetic pyrethroids:
The synthetic pyrethroids
have an LD50 of 2305 mg/kg and
the naturally occurring pyrethrins that are approved for organic production have
an LD50 of 1500mg/kg. Lower LD50
means more toxicity. So, the natural pyrethrin which is approved for organic production
is more toxic than the synthetic pyrethroid which is not approved for organic production.
that you know what LD50 means,
it mat prove interesting to compare the toxicity of various commonly