Sorry for the late answer.
I’ve been tasting the sample with pesticides and the pesticide-free sample in parallel on the same session.
The main things I could notice with pesticides is a feeling of tightness in the back mouth and throat as well as a nausea-like sensation in the stomach. This is a feeling that lasts for a few hours so I re-tasted the pesticide-free sample some days later and nothing happened that time. So I assume that it is really linked with the chemicals present in the sample with pesticides. It is also some of he points that David from EoT points out, there are some other subtle things that I didn’t take time to find because I wasn’t happy to drink this sample with pesticides over and over until I could feel and smell it...