At those levels, you really do start to get into trouble as molecular dynamics are subtly changed (or at 100T+, not so subtle, perhaps). I wonder if the impact would be similar to the effect of heavy water (if you consume it chronically until a large fraction of your body mass becomes deuterated), at first.
Would it be deadly or just sickening after a while?
I would guess, as you go up in field, the effects become more severe, and more immediate. Much like ionizing radiation, without the post-exposure effects. Heh, well, I don't know, maybe proteins will fold wrong and DNA will get scrambled at a high enough field strength, and then you're kind of screwed?
At a glance, I don't see much about high-field effects. Apparently 18T magnets are being used to help grow better protein crystals, for crystallography and x-ray diffraction purposes. Can't be too bad at that level, I suppose.
On that note; the mind boggles to even conceive of 100T+ fields, both to experience, and to attempt to generate, such a feat! The Maxwell stress from that flux density is already greater than any known steel can withstand.
Speaking of "swimming in dynamite", 100T is merely half the energy density of TNT (1001 ksi equivalent, hey, that's easy to remember!), not at all a bad SWAG!
I'm not up on my high-field molecular dynamics to know what kind of effects occur at such high fields, but it's entirely possible that different electronic configurations (orbitals), binding and ionization energies, spin couplings, and so on, would become relevant. Let's see, there is such a thing as strong-field Zeeman splitting, so the atomic case is well studied. In short, around 30T, chemistry probably isn't too different, but it might be different enough that you feel it, perhaps immediately (neural effects?), perhaps over continued exposure; and different enough that perhaps life-as-we-know-it cannot reproduce without additional evolution to fix things (much as life in space is already know to be a bit weird). At fields over 100T, it wouldn't seem possible for any solid material to exist anymore, as we know it: it would be torn apart, or crushed into electron-degenerate matter. The latter, of course, is the only sort of environment we can theorize about (and observe, from very great distances, of course): astronomical objects like white dwarfs and neutron stars. Environments so extreme, so utterly hostile, and so alien that we have no hope of recreating their environments in the laboratory...
Tim