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Nuclear Power
Published in Robert Ehrlich, Harold A. Geller, John R. Cressman, Renewable Energy, 2023
Robert Ehrlich, Harold A. Geller, John R. Cressman
Hormesis, which is well established for agents or substances such as sunshine, iodine, and iron, is the notion that while very high levels are harmful to health, low doses are actually beneficial. Whether at very low levels the effects of radiation are in fact harmful, beneficial, or neutral, the risks of radiation need to be assessed in comparison to other risks. For example, taking a plane ride or moving to Colorado will very slightly increase your exposure to radiation, but few people would let this factor dictate their decision-making about these activities. In the former case, the risks of flying (or more importantly driving to the airport) likely far outweigh the extra risk of dying from cancer, and in the latter case, moving to Colorado, despite its slightly higher background radiation level, will probably improve your health in view of the climate, lack of smog, and healthy lifestyle of the populace.
UV Light for Fresh Produce and Grain
Published in Tatiana Koutchma, Ultraviolet Light in Food Technology, 2019
Exposure to UV at very low doses over hours or even days triggers a series of biochemical events within the plant tissue. The term “hormesis” has been applied to this type of the UV treatment. According to Shama (2007), “hormesis” involves the use of small doses of potentially harmful agents directed against a living organism or living tissue in order to elicit a beneficial or protective response. Hormetic UV treatment is distinguished from conventional UV treatment. In conventional treatment, the UV is directed towards microorganisms that are present on the surfaces of an object, whereas in case of hormetic UV treatment, the object itself is exposed to the incident UV. The purpose of the treatment is to elicit an anti-microbial response in the fruit tissue. Both types of UV treatment employ the same wavelengths; however, for hormetic treatments, only low UV doses are applied (Shama & Alderson, 2005). Plant defence mechanism that is triggered by the hormetic UV dose is not yet fully known and understood. Figure 6.1 schematically presents some of the biochemical responses of plant membrane that were recently reported. It was found that UV-C hormetic treatment at UV exposures in the range of 40–430 mJ cm−2stimulate the activity of several groups of enzymes that play different roles in plant antimicrobial defence actions. This includes: (1) enzymes of peroxidases and reductases that are responsible for the oxidative burst and formation of lignin polymers generating structural barriers against invading pathogens; (2) glucanases and chitinases that exhibit lytic activities towards major fungal cell wall components; and (3) L-phenylalanine ammonia lyase (PAL) – involved in biosynthesis of phenolics which are characterized by antioxidant and anti-microbial activities (Erkan et al., 2008; Pombo et al., 2011).
Statistical modeling of hormesis quantities in inverted U-shaped dose-response relationships by reparameterization of a bilogistic model
Published in Journal of Environmental Science and Health, Part A, 2022
Christian O. Nweke, Oluchukwu R. Nwangwu, Reuben N. Okechi, Nnamdi N. Araka, Chukwudi J. Ogbonna
Applying the suggested 4-step modeling approach to determine hormesis quantities in a hormetic dose-response relationship is challenging. In all dose-response data sets, substituting an individual parameter in a model by reparameterization does not affect the goodness-of-fit statistics and estimation of other parameters. Similar observations have been reported elsewhere while applying the reparameterized Cedergreen–Ritz–Streibig hormesis model to determine effective doses and other hormesis quantities.[11,12] Although the use of the reparameterization approach to modeling hormesis has been previously criticized,[9,14] the present study and previous studies[11,12] proved that model reparameterization could be successfully applied to 6- and 7-parameter hormesis models.
Air pollution and molecular changes in age-related diseases
Published in International Journal of Environmental Health Research, 2022
B. Hermanova, P. Riedlova, A. Dalecka, V. Jirik, V. Janout, R. J. Sram
The effect of exposure may be positive, negative, or hormetic. Hormesis is the term for the phenomenon where, up to a certain point, low exposure has a positive effect on the body, while the effect becomes negative from a certain point. This means that in the short-term specific molecular parameters may improve, for example, the telomere may become longer for a time, or the activity of certain antioxidant enzymes may increase (Gurgueira et al. 2002; Dioni et al. 2011; Hou et al. 2012; Rossnerova et al. 2017). Generally, upon long-term exposure to low doses of pollutants the body develops an adaptive response, meaning that exposure does not cause as much damage in the body as if the body had been exposed to the same concentration suddenly.
Impact of copper treatment on phenylpropanoid biosynthesis in adventitious root culture of Althaea officinalis L.
Published in Preparative Biochemistry & Biotechnology, 2022
Yun Ji Park, Nam Su Kim, Ramaraj Sathasivam, Yong Suk Chung, Sang Un Park
Heavy-metal toxicity, caused due to the metals stored in soils, surface water, or produced through industrial and mining processes, leads to hazardous effects in animals and plants.[1] Treatment with highly concentrated heavy metals exerts adverse effects on plant metabolism, including photosynthesis, respiration, disruption of membranes, and enzymatic activity.[2,3] In addition, heavy-metal contamination induces changes in the composition of chemicals produced by plants. Heavy metals that have mobility in plants cause responses such as reduction in the biosynthesis of natural plant products, loss or inactivation of vital enzymes, and damage to nonessential processes, including secondary metabolite accumulation.[4] However, heavy metals have become important abiotic stress factors for living species, as they are often used in industrial production and have high bioaccumulation and toxicity.[5] Heavy metals may enhance the production of therapeutically active constituents and change the ultra-morphological characteristics of medicinal plants.[4] Heavy metals are likely to be used as elicitors because they are cheaper and chemically more defined than biotic stress agents. Therefore, the application of heavy metals to plants has been proposed as an ideal system for the accumulation of beneficial compounds.[6] However, heavy metals may be toxic depending on the type of metal, its oxidation status, pH, concentration, duration, and so on, resulting in the death of organisms. The toxicity of a particular substance is based on a range of elements, including how much of the substance is subjected, how it is exposed, and for how long. It has been also documented that low-dose chemicals can have positive effects, called hormesis, and high-dose adverse effects.[7]