RF Safe argues that “no effect” findings in some RF exposure studies should be interpreted as meaningful negative controls rather than as evidence that RF has no biological effects. The post presents RF Safe’s “S4–Mito–Spin” framework, claiming certain skin cell types (fibroblasts and keratinocytes) are predicted to be relatively resistant to non-thermal RF effects, so null results in these cells can be consistent with the model. It cites in-vitro studies at 3.5 GHz (5G-modulated) reporting no changes in ROS measures, stress responses, or UV-B DNA repair kinetics under specified SAR conditions, and frames these nulls as boundary conditions rather than a general safety conclusion.