Final answer:
The Hormesis Dose-Response Model proposes that low exposures to toxins or radiation can have beneficial biological responses, in opposition to high doses which are harmful. While this model suggests a threshold effect rather than a linear relationship with dose, the linear hypothesis remains the standard for regulatory safety due to the uncertainties surrounding low-dose benefits in humans.
Step-by-step explanation:
The Hormesis Dose-Response Model is a concept used in toxicology and radiation biology to describe a biphasic response to exposure to a substance or environmental factor. According to this model, low doses of a toxin or radiation may induce a beneficial biological response, such as the stimulation of repair mechanisms or adaptation processes in cells. This contrasts with high doses, which can cause significant damage or be lethal. The model suggests that there is a threshold or a zone where the exposure could turn from being beneficial or neutral to detrimental, calling into question the linear hypothesis that any amount of exposure carries a risk proportionate to dose. A dose less than 100 mSv (low dose) might stimulate positive effects, such as improved resilience to higher doses. However, a dose greater than 1 Sv (>100 rem) (high dose) typically leads to harmful effects.
Despite the hormetic model highlighting potential benefits of low-level exposures, the evidence for such effects, especially in humans, is often uncertain. Consequently, the linear hypothesis remains the more cautious approach used in regulations to safeguard public health from exposure to radiation and toxic substances. Yet, some researchers point to hormesis as a more accurate reflection of how low-dose exposures impact biological systems.