Interpreting ‘Dose-Response’ Curves using Homeodynamic Data: With an Improved Explanation for Hormesis

• Published in: Dose-response 2009-07, Vol.7 (3), p.221-233
• Main Author: Stebbing, A.R.D.
• Format: Article
• Language: English
• ISSN: 1559-3258; 1559-3258
• DOI: 10.2203/dose-response.08-020.Stebbing

A re-interpretation of the ‘Dose-Response’ curve is given that accommodates homeostasis. The outcome, or overall effect, of toxicity is the consequence of toxicity that is moderated by homeodynamic responses. Equilibrium is achieved by a balance of opposing forces of toxic inhibition countered by a stimulatory response. A graphical model is given consisting of two linked curves (response vs concentration and effect vs concentration), which provide the basis for a re-interpretation of the ‘Dose-Response’ curve. The model indicates that such relationships are non-linear with a threshold, which is due to homeodynamic responses. Subthreshold concentrations in ‘Dose-Response’ curves provide the sum of toxic inhibition minus the homeodynamic response; the response itself is unseen in serving its purpose of neutralizing perturbation. This interpretation suggests why the α- and β-curves are non-linear. The β-curve indicates adaptive overcorrection to toxicity that confers greater resistance to subsequent toxic exposure, with hormesis as an epiphenomenon.