Understanding the science
The monarch risk assessment has two basic
- What is the potential for toxicity
for a particular species?
- What is the likelihood of exposure
to the toxicant?
This is the standardized approach for estimating risk
posed by pesticides, industrial byproducts and other potential toxicants
to many non-target species. The scientific community considers it
the most credible method for determining actual risk and it is also
the method accepted by the EPA.
Examination of the natural habitat of monarch
butterflies indicates several events must coincide for the possibility
to even exist that Bt pollen could cause harm to the monarch
population. First, monarchs have to have laid eggs on milkweed plants
and the caterpillars must emerge from the eggs just as the Bt
corn is producing pollen. Corn, including genetically modified corn,
only produces pollen during a narrow window of seven to 10 days
each year. Next, the caterpillars must feed on milkweed leaves with
Bt corn pollen. Third, the caterpillars must consume enough
Bt pollen to reach potentially toxic levels. The Bt
corn/monarch risk assessment assembled the likelihood of all of
these circumstances occurring.
The risk assessments key finding: The potential risk to
monarch butterfly populations from Bt corn pollen is negligible.