Artificial toxin/poison/dye/fragrance-free. You can shove as much naturally occurring toxins in the product as you like, and both marketers and regular people will agree it's "chemical-free".

And that's side-stepping the whole "artificial" vs. "natural" nonsense. 'spacehome may be pedantic in this context, but in general, he's right - regular people have their model of the world ridiculously out of sync with reality. Which is of course readily exploited by advertisers selling "chemical free", "natural", "organic" products, which are no better (and sometimes worse) than the "artificial" ones, but still command a premium price.