Bacteriostasis

Holland³

1999

Risk Analysis

160

104

From a comprehensive search of the literature, the hormesis phenomenon was found to occur over a wide range of chemicals, taxonomic groups, and endpoints. By use of computer searches and extensive cross-referencing, nearly 3000 potentially relevant articles were identified. Evidence of chemical and radiation hormesis was judged to have occurred in approximately 1000 of these by use of a priori criteria. These criteria included study design features (e.g., number of doses, dose range), dose-response relationship, statistical analysis, and reproducibility of results. Numerous biological endpoints were assessed, with growth responses the most prevalent, followed by metabolic effects, reproductive responses, longevity, and cancer. Hormetic responses were generally observed to be of limited magnitude with an average maximum stimulation of 30 to 60 percent over that of the controls. This maximum usually occurred 4- to 5-fold below the NOAEL for a particular endpoint. The present analysis suggests that hormesis is a reproducible and generalizable biological phenomenon and is a fundamental component of many, if not most, dose-response relationships. The relatively infrequent observation of hormesis in the literature is believed to be due primarily to experimental design considerations, especially with respect to the number and range of doses and endpoint selection. Because of regulatory considerations, most toxicologic studies have been carried out at high doses above the low-dose region where the hormesis phenomenon occurs.

Section: Microbial Responsesmentioning

confidence: 99%

Hormesis: A Highly Generalizable and Reproducible Phenomenon With Important Implications for Risk Assessment

Calabrese

Holland³

1999

Risk Analysis

160

104

“…Their work set the stage for other investigators from their institution and elsewhere to standardize doses based on molar concentrations rather than on a percentage basis as had been typical at that time. It should be noted that in their initial work with approximately 70 agents there was no case where a stimulatory response was noted. The lack of a stimulatory response in these numerous experiments was not, in retrospect, unexpected, given that the intent of the authors was to determine the concentration at which the solutions first permitted the radicle to survive.…”

Section: Plant Toxicologymentioning

confidence: 99%

“…Marshall and Hrenoff described the action of disinfectants as a flexible blending of differential modes or degrees of activity. 70 The initial response band describes a range of dilutions of an agent between 0% and the greatest dilution which can be shown to exert an action on the bacteria. This was called the ineffective band (i.e., no effect zone).…”

Section: Bacteria Introductionmentioning

confidence: 99%

Chemical hormesis: its historical foundations as a biological hypothesis

Calabrese¹,

2000

Hum Exp Toxicol

248

Despite the long history of hormesis-related experimental research no systematic effort to describe its early history has been undertaken. The present paper attempts to reconstruct and assess the early history of such research and to evaluate how advances in related scientific fields affected the course of hormesis-related research. The purpose of this paper is not only to satisfy this gap in current knowledge, but also to provide a foundation for the assessment of how the concept of hormetic dose-response relationships may have affected the nature of the bioassay especially with respect to hazard assessment practices within a modern risk assessment Eramework.

“…In fact, as a result of his very strong reputation in the field of bacteriology and his promotion of the concept that low doses of toxic substances stimulate biological processes, this phenomenon became known as Hueppe's rule (as well as the Arndt-Schulz Law). Numerous papers (23,26,27,43,46,55,87,88) and dissertations (41,42) in bacteriology were published that were generally highly supportive of the hormetic hypothesis and the Arndt-Schulz law. By the 1930s, numerous leading botany and microbiology textbooks in the United States devoted considerable attention to this phenomenon and recognized it as a legitimate and central aspect of their respective fields.…”

Section: Introductionmentioning

confidence: 99%

U-Shaped Dose-Responses in Biology, Toxicology, and Public Health

Calabrese

Annu. Rev. Public Health

2001

309

185

The occurrence of U-shaped dose-response relationships (often termed hormesis) has been documented in numerous biological, toxicological, and pharmacological investigations. Many of the endpoints studied are of considerable significance to public health (e.g. body weight, cholesterol levels, ethanol consumption, longevity, cancer incidence, etc). Despite the fact that U-shaped dose-responses are widely and independently observed, little attempt has been made to assess this phenomenon in an integrative manner. This review provides an overview of the historical foundations of hormesis and a discussion of its definition within a mechanistic framework. The occurrence, generalizability, and biological significance of U-shaped dose-response relationships along with the concept of biological optimality are addressed.