Tales of two similar hypotheses: the rise and fall of chemical and radiation hormesis

This paper compares the historical developments of chemical and radiation h ormesis from their respective inceptions in the late 1880's for chemical ho rmesis and early 1900's for radiation hormesis to the mid 1930's to 1940 du ring which both hypotheses rose to some prominence but then became marginal ized within the scientific community. This analysis documents that there we re marked differences in their respective temporal developments, and the di rection and maturity of research. In general, the formulation of the chemic al hormesis hypothesis displayed an earlier, more-extensive and more sophis ticated development than the radiation hormesis hypothesis. It was able to attract prestigious researchers with international reputations from leading institutions, to be the subject of numerous dissertations, to have its fin dings published in leading journals, and to have its concepts incorporated into leading microbiological texts. While both areas became the object of c riticism from leading scientists, the intensity of the challenge was greate st for chemical hormesis due to its more visible association with the medic al practice of homeopathy. Despite the presence of legitimate and flawed cr iticism, the most significant limitations of both chemical and radiation ho rmesis and their respective ultimate undoing were due to their: (1) lack of development of a coherent dose-response theory using data of low dose stim ulation from both the chemical and radiation domains; (2) difficulty in rep lication of low dose stimulatory responses without an adequate study design especially with respect to an appropriate number and properly spaced doses below the toxic threshold; (3) modest degree of stimulation even under opt imal conditions which was difficult to distinguish from normal variation; a nd (4) lack of appreciation of the practical and/or commercial applications of the concepts of low dose stimulation.