The concern is theoretical and unproven in humans, but it is not dismissible on current evidence, since undiagnosed or pre-malignant lesions would by definition not be known about at the time of exposure
This is so that you protect yourself and maintain the quality of the contents
FDA's 2024 review states the mechanism of action is still unknown, which limits how confidently any specific physiological effect can be predicted in humans
PubMed record Xu B, et al
Cycling 4-6 weeks on / 2-4 weeks off is the most common community-derived structure used to manage this
We trace it from 1906, when allergy was first defined as a real clinical thing, through the 1950s clinical ecology movement, through cytotoxic testing, IgG panels, electrodermal screening, and bio-resonance, and finally to the at-home hair test in your DMs