These days, tyre microplastics and diesel particulates are still a concern, but there's little hard science around the hazards of eating them in small quantities - there's microplastic in basically everything, to some degree, so you're not making it appreciably worse - and agricultural farm machinery is a worse diesel PM offender by far than a street's worth of modern cars.

One would hope that more expensive chocolate would have a value chain to show that it’s been dried in a proper manner.

Nothing beats random sampling though.