You’re asking a question that doesn’t have an exact answer. Whether something is “dirty, synthetic and toxic” is largely a matter of opinion.
If you believe professional toxicologists Polyisobutene & Hydrogenated Polyisobutene are clean, safe and non-toxic in cosmetics. You can read all the safety testing that has been done on the ingredients here. Note, this includes animal testing. https://online.personalcarecouncil.org/ctfa-static/online/lists/cir-pdfs/FR687.pdf
But if you find the opinions of scaremongering groups, bloggers, and sensationalist journalists more credible, then the ingredients would not fit your requirement of “clean, natural, and non-toxic.”
There is a lot of BS and non-science based opinions about cosmetic ingredients out there. None of the legitimate products on the market represent any significant cancer risk for the vast majority of consumers. NONE of the “all natural, non-toxic” products on the market are more safe than standard, synthetic products. That’s what the science says. But fearmarketing is compelling and effective. Do you want to believe science or marketers? It’s really up to you.
I should mention that no one wants to sell a product line that is “dirty, synthetic, and toxic.” You’ll need a better point of differentiation than that to be successful.