Roughly every 7 years for most of the body, major organs tend to take longer, more like 10. Your brain replaces cells at a way slower rate, you'll only Theseus your brain about 80% at best if you live a long healthy life.
Thats not the point though, 390 mg is a lot even for a healthy adult.
Not under the current systems, exploitation is built in, no way to avoid it if you directly engage by starting a business. You're missing the point though, this meme is about scalpers, people who buy as much as possible of a high demand item to sell it higher than its legitimate market value. When the profit off the product exceeds costs to provide the product you're exploiting people and scapers attempt to maximize that exploitation.
Taking advantage of you excess resources to manipulate people into give you theirs, is the problem.
Tom Paris tells the Doctor holograms are just light and aren't real matter, the Doctor turns and slaps Tom.
They were frequently combined, the white pages were people in the local area and the yellow pages were businesses. I don't actually remember seeing white pages in any phone booths or by pay phones but that may just be where I lived.
A calorie is the amount of heat needed to raise the temperature one kg of water by 1°C, so uranium has quite a few, hard to digest though.
Edit: I was curious so I looked it up, 1 gram of uranium has 20 billion calories