There’s some really good research and info on this site: https://www.anourishingharvest.com/

When it comes to chemical pollutants and health I think it’s the concentrations that are more relevant than the scale. Grams of toxins spread over a vegetable garden could easily be worse than tonnes of toxins spread over a big farm.

It’s laborious to measure the amount of known toxins in your soil and even more laborious to measure the health impacts of them, so I just stick to using things that I know the soil can process naturally. Apart from not wanting to poison myself I also don’t want to poison future generations or create a dystopian problem for them to have to fix.

To be honest though, in my experience mulching is a bit overrated and ends up being pretty much the same amount of work/hassle as doing a bit of a digging here and there. Also, digging, weeding and tidying help you to get to know the life of your garden and become more intimate with it, with I think is totally solarpunk :)