Awesome! I've been following bionerd23's youtube channel for a while and really enjoy the videos she's done. Glad to see more folks being introduced to her too!
Is she exposing herself to more radiation than is safe?
Is there a very high likelihood she's going to make herself sick? I watched this one https://www.youtube.com/watch?v=6kg4vVYKc90 and she seems to be pretty callous with that hot particle.
well, if its over 100 mSv/h, then acute radiation sickness begins after ~2 hours (noticable reduced blood cell count from 200 mSv acute dose onward, though you'd only FEEL sick after another 3 or 4 hours). but yeah, as the inverse square law applies, there's nothing to fear with this particle. and yep, the spectrum was done by a HPGe, as usual. :)
I thought it meant that if you're exposed to 100mSv/h, you'll get sick around 2 hours later... but what it means is a full body dose for 2 hours is enough to make you sick.
Therefore 5 minutes to the fingers is probably OK.
what damage is being done by holding that grain?
The girl seems to have a good understanding of dose safety. But a poor understanding of biological effects, just like everyone else. Beta vs alpha vs gamma radiation have very different biological effects and sieverts, the measuring units that take some of these differences into account, are a gross over simplification. You can kill someone with a radiation dose well below the lethal one in Sv and you can survive a dose above the lethal one...
Biological systems have very complicated relationships with radiation in general, that's why even the health impact of non-ionizing radiation needs to be investigated (yeah, your cellphone is most likely safe ;) ...but you know that you have at least some cells in you body that respond even to non-ionizing EM radiation - they are in your eyes and thanks to them you can read this :) )
http://en.wikipedia.org/wiki/Anatoli_Bugorski Note: You may want to avoid doing an image search though.
More generally in the short term it's fast growing tissue that's most at risk. So, exposure that is quickly lethal may not do a lot of damage to slow growing tissues. Long term you can often remove severely affected tissues so a person can often survive much higher doses to their arms and legs vs torso.
PS: Another issue relates to population sizes. A 0.1% risk to everyone in the US kills more than 300 thousand people and is a major issue. A 0.1% risk to one person may not seem that bad as that's around the default risk every month for a 55 year old male.
Her biggest problem from holding something like that radioactive grain in hand would be the gamma rays causing mutations in the cells in her hand that would then lead to cancer in the log term. Like I'd imagine she will be sick with some bone cancer or leukemia or a random sarcoma in like 10 - 15 years from now. Maybe even longer if she has inherited some good DNA-repair genes and anti-cancer-immunity genes. Or sooner if she wasn't so lucky at the genetic lottery and if she has other risk factors too...
And then there's the radioactive dust... I'd imagine she has inhaled quite a lot of it along her trips, and this is probably her biggest short term (think "less than 10 years") concern.
Generally a whole body dose of 1 sievert will increase your odds of getting cancer by 10% over your life. I don't know how much she's been exposed to but while my guess is that while future cancer is a concern it really isn't a sure thing.
Which is probably the biggest problem for biological systems - alterations in the DNA caused by radioactivity.
edit: Here's a good video that shows some of the gear and safety equipment for more serious explorations: https://www.youtube.com/watch?v=CdhdCbDch6A
It certainly seems that she knows what she is doing, and isn't just jumping in for giggles when the meters start beeping. She even mentions the inverse square law in the video you linked.