Not yet investigated
What we have so far
Two effects named before 1900: Paul Bert, seizures at high partial pressure, and Lorrain Smith, lung injury from prolonged exposure. Divers know the first; hospitals meet the second.
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.