Are you suggesting pesticides have something to do with "the shakes"?

When I was younger, back in late '50s, early '60s, I noticed many old farmers that had "the shakes", or medically known as Essential Tremors.

What would've caused it back then? Sitting/standing/walking behind horses for hours & hours & hours?

At the same time, I notice that many farmers now do NOT have the shakes. I'm not sure about those in other professions.