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H2O-1999-24-(Hanekamp, Bast, Schuiling, Donze)

November 1999

Authors:

J.C. Hanekamp

University College Roosevelt

Aalt Bast

Maastricht University

ResearchGate has not been able to resolve any citations for this publication.

ResearchGate has not been able to resolve any references for this publication.

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H2O-1999-21-(Hanekamp, Bast, Schuiling, Donze)

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Death by Dose—The Most Toxic Compounds

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The most toxic compound in our global environment is oxygen. The English theologian and chemist Priestley discovered oxygen in the 18th century. Not only the discovery of oxygen was a scientific struggle, also during evolution the development of life on earth as a whole was a fight with and against oxygen. Life had to adapt to oxygen. Oxygen has an unusual reactivity and is very toxic for aerobic ... [Show full abstract] human life. In fact the paradox of human life is that it depends on the presence of oxygen and at the same time accelerates decay (disease and death) as a result of continuous exposure to oxygen. Conversely the reactivity of oxygen is used by the body to oxidize endogenous compounds like hormones or fatty acids but also of xenobiotics, compounds which are strange to the body like drugs or exogenous toxins, to facilitate excretion. The reactivity of oxygen plays a central role in immune defense. Oxygen can easily take up electrons in the body, which results in the formation of reactive oxygen species (ROS) that may destroy foreign and pathogenic organisms such as bacteria and viruses. However, if too much of these ROS are produced, damage to all kinds of biomolecules can arise and lipid-, protein- or DNA-damage can occur. The use of ROS for several physiological body functions is possible because both nonenzymatic compounds like the antioxidants vitamin C or vitamin E and a system of antioxidant enzymes protect against ROS-induced injuries. It is increasingly recognized that mild forms of oxidative damage by ROS may even lead to adaptation which increases the endogenous protection. Adaptation thus appears the key word both in evolution as well as in explaining the use of oxygen in aerobic life.

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Hormesis in precautionary regulatory culture: Models preferences and the advancement of science

December 2007 · Human & Experimental Toxicology

The article focuses on flaws in the actual approaches of exposure to a chemical of recipient organisms. It demonstrates the excessive use of arguments based on adverse effects and underlines the necessity to take adaptive effects seriously. Regulators are invited to rethink their inclination to the 'When in doubt, keep it out.' precautionary approach, with results in counter-productive and costly ... [Show full abstract] regulations. The authors are clear about the necessity to include hormesis, in the form of a toxicological insignificant exposure (TIE) level, related to the concentration, as a regulatory translation of adaptive effects. This inclusion might well be the 'brake' for the looming 'collision' with reality of the actual linear toxicological models. This analysis includes the advice to EPA, not to follow the 'witch hunt of synthetic chemicals' as embodied in the EU REACH program.

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Chemicals and Health - Thought for Food

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In our contribution we concisely question and answer some basic notions on food, health, and safety. We show that for some food components such as flavonoids, a whole range of small toxicological effects that have been uncovered the last decade on the whole confer benefits to human health. This development underlines the notion that health is adaptation with respect to the exposures humans ... [Show full abstract] experience when consuming food.

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