Deer are drawn to road sides, where they eat herbicide treated vegetation(documented), then over the following years you see developmental malformations in these deer, cranial facial malformations for example that have been documented in captive animals fed herbicides. Take the herbicides away or look at areas with less or no exposure and you don't see these malformations.
So what causes the malformations that you should not document unless you have been to college? This part of it is the easy part, this the sixth grade observational life science part of the equation.
I'm not talking developmental malformations. I'm talking compromised immune systems and/or higher incidences of mortality.
An example of this would be something such as this:
Group 1: Animals subjected to herbicide exposure
Group 2: Animals not subjected to herbicide exposure
Group 3: Animals subjected to herbicide exposure with selenium supplementation
Group 4: Animals not subjected to herbicide with selenium supplementation
Test if there is a significant difference among neonatal survival and adult survival over a four year period.
This would potentially establish a causative affect of herbicide on populations.