https://bookshop.org/books/the-body-electric-electromagnetis...
Becker's lab was, for decades almost uniquely in the US, permitted to engage in research on effects of electromagnetic fields and currents on living systems.
I say "permitted" because it was career death to even mention it, most places. To this day, the official standards for exposure to E-M radiation admit possible effects only of heating, but Becker was able to profoundly alter growth and, crucially, regeneration patterns via sub-nanoamp electric currents.
I have no idea how or why the stricture was applied elsewhere, but Becker's free hand appears to have been a product of his employment by the US Veterans Administration, which would have liked for him to discover a way to regenerate veterans' and servicemen's severed limbs, so he did not depend on grants from the usual sources such as NSF and NIH, which must have kept a tight rein.
In 1987 I sneaked into a presentation at a conference in Szeged, Hungary, where an American biologist presented results of electromagnetically stimulating beetle larvae to grow 4x normal size. She remarked she had been unable to present such results at any US conference.