Not yet investigated
What we have so far
One hydrogen in 6,400 carries a neutron. The kinetic isotope effect is real chemistry; the cancer claim rests on a handful of small studies from a narrow set of investigators.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.