The runoff levels are tested to be in the nM range, but they’re applying 10-50 mM to each insect directly injected. Even if they’re in the field and encountering mM concentrations as applied, contact with an insect probably isn’t going to transfer much to the bloodstream as there’s no direct transfer pathway for animals.

wouldn't the primary technicality here be exposure time? Rather than exposure levels. Ultimately depends on the lifespan of the insect itself. But this is a pretty significant factor to why things like leaded gas got banned.