Use Of Hormesis Research Articles

“Is Hormesis Applicable as a Pro-Healthy Aging Intervention in Mammals and Human Beings, and How?”

“Is Hormesis Applicable as a Pro-Healthy Aging Intervention in Mammals and Human Beings, and How?”

Evolutionary Theory and Studies of Model Organisms Predict a Cautiously Positive Perspective on the Therapeutic Use of Hormesis for Healthy Aging in Humans

Hormesis, the beneficial effects of mild stress exposures, is a well documented phenomenon in a range of organisms. The documentation mainly relies on relatively simple and controlled laboratory investigations. In order to better understand hormesis and predict the outcome of more complex and realistic conditions, a number of key issues should be investigated in much more detail. One obstacle is the development of precise treatments optimized for single individuals. Only then can we progress with the use of hormesis as a therapeutic tool for humans.

Ideological toxicology: invalid logic, science, ethics about low-dose pollution

As illustrated by the case of ethanol, claim H is that, for some biological endpoints, low-dose toxins and carcinogens exhibit hormesis, a beneficial or adaprive response characterized by biphasic dose responses and resulting from compensatory biological processes following an initial disruption in homeostasis. From this uncontroversial claim H, however, the paper argues that some toxicologists invalidly infer HG (that H is generalizable across biological model, endpoint measured, and chemical class) and HD (that a strong case can be made for the use of hormesis H as a default assumption in the risk-assessment/regulation process), Evaluating HG and HD, this paper argues for 5 claims. While (1) H is true, (2) HG falls victim to several logical fallacies and therefore is logically, scientifically, and ethically invalid. (3) Because it relies on logical fallacies, confuses necessary and sufficient conditions, and violates at least 5 sets of ethical norms, HD is logically, scientifically, and ethically invalid. (4) Five remedies could help address HG-HD flaws and failure to adequately assess low-dose exposures. (5) Three objections to these criticisms of HG and HD are easily answered.

A critique of the use of hormesis in risk assessment

There are severe problems and limitations with the use of hormesis as the principal dose-response default assumption in risk assessment. These problems and limitations include: (a) unknown prevalence of hormetic dose-response curves; (b) random chance occurrence of hormesis and the shortage of data on the repeatability of hormesis; (c) unknown degree of generalizability of hormesis; (d) there are dose-response curves that are not hormetic, therefore hormesis cannot be universally generalized; (e) problems of post hoc rather than a priori hypothesis testing; (f) a possible large problem of 'false positive' hormetic data sets which have not been extensively replicated; (g) the 'mechanism of hormesis' is not understood at a rigorous scientific level; (h) in some cases hormesis may merely be the overall sum of many different mechanisms and many different dose-response curves - some beneficial and some toxic. For all of these reasons, hormesis should not now be used as the principal dose-response default assumption in risk assessment. At this point, it appears that hormesis is a long way away from common scientific acceptance and wide utility in biomedicine and use as the principal default assumption in a risk assessment process charged with ensuring public health protection.

How much is enough to accept hormesis as the default? or ‘At what point, if ever, could/should hormesis be employed as the principal dose-response default assumption in risk assessment?'

Hormesis as the principal human dose-response default assumption must reasonably await the development of the science of toxicology and molecular biology before this dramatic change can occur. The inherent quality of typical toxicological data is simply too limited to allow for an understanding of what really occurs in human tissues at the relatively low doses generally extant in the environment. Thus, forwarding or asserting the quantitative use of hormesis (or any model of low dose-response) without this reasonable knowledge is simply an argument without data. It is this writer's opinion that any widespread and default acceptance of hormesis will need to look forward to and draw upon the inevitable development and use of tools from the realm of molecular biology and a resulting and distinct change in the entire toxicological testing paradigm.

Hormesis: the new approach in risk assessment?

Hormesis is a dose-response phenomenon characterized by either a U-shaped or an inverted U-shaped dose response depending on the different end points measured. In a paper in this issue of the journal, Drs Jayjock and Lewis advocate for the application of hormesis in the field of industrial hygiene, and suggest the use of hormesis as a default assumption in the risk assessment process. However, there are many difficulties for the utilization of hormesis in the field of industrial hygiene. Indeed, it is impossible to test the hormesis hypothesis in many commonly employed experimental model systems for end points of public health concern, and the mechanism of low-dose stimulation of hormesis is not clear. Even if hormesis were proven biologically, its assessment is limited due to difficulties of study design, biological markers selection, statistical power considerations, model and end point selection, and risk model approaches.