Thanks for this important contribution. As someone who works with pesticides, I try to remain abreast of toxicology concerns regarding xenobiotics. This paper helps me understand the concept of decelerating dose-response curves.

Clearly natural materials can exhibit decelerating dose-response (Ar, Pb, for example). Are there natural organic compounds that exhibit such responses? Is decelerating dose-response more likely with xenobiotic compounds than natural compounds?

With respect to the chemicals we are exposed to (both natural as well as synthetic), I am aware of three possible responses:
1. Linear dose-response curves
2. Decelerating curves
3. Hormetic responses (https://www.nature.com/ar...)

Are decelerating curves more likely than hormetic responses?

Thanks for your thoughts and insights.