There is such a mixture of ideas here. Without being too categorical, but wearing my “I’m a biochemist with PD who keeps up to date with things” hat ….
1). Glyphosate (Roundup) has been allegedly associated with lymphoma. The evidence is fairly feeble and it’s the best herbicide to use if you have to use any (as I am a 99% organic wildlife gardener). No know link with PD. The weedkillers that **are** possibly linked to PD are diquat and paraquat.
2). Insecticides associated with PD – and this is a strong correlation – are the organophosphates, like malathion.
3) Asbestos is only associated with a rare lung cancer called mesothelioma.
Don’t forget that our bodies have superb abilities to de-toxify a lot of man-made chemicals. This is not to say that PD isn’t triggered by a combination of environmental factors. I worry most about the use of plastics in things we eat and drink. Endocrine disrupters and all that.
John H