It accumulates in bone, yes, but not all of it does. It also collects in blood and organs where it is passes fairly quickly. The FDA sets their guidelines based on safe blood levels of lead and their recommendation is I think 1/10 the actual value to build in a pretty big safety buffer.
We're already exposed to lead constantly through the environment, etc. It's not just present in foods and other man made things. It's definitely in many of the foods we eat, not just protein powder. Root vegetables, grain crops, etc. https://www.sciencedirect.com/science/article/abs/pii/S0963996920303951
I don't think it's necessarily a bad idea to try your best, but I also don't think it's worth stressing over with these protein powders compared to other stuff you may already be ingesting.
The MADL for lead outlined by Proposition 65 is 0.5 µg of lead per day. This value was set, arbitrarily in 1989, even though scientific evidence continues to show that it’s wildly unrealistic and not remotely near an exposure that would be a health concern. It remains unchanged because Prop 65 is a political tool, not a scientific one. Consumer Reports decides to ignore FDA interim reference levels for lead in their assessment. These levels are 8.8 µg per day for reproductive age females and 12.5 µg for general adults, 17.6-times and 25-times higher daily exposure levels compared to the Prop 65 levels, respectively, and are already extremely conservative (more on how those are calculated in a moment).
Not saying you shouldn't take it into consideration, but it's not as big of a deal as CR is making it out to be.
This happened in my game. I spoke with the player about having his character swapped with another version of him from an alternate universe, and he was down for it. Then it happened in game. None of the players realized it. This went on for years (literal real time years) before he betrayed them. It was delicious.
Ah, that's a bummer. Thank you for finding it!