Long term bad news
November 11, 2016 7:05 AM   Subscribe

I've seen lots of discussion over the years about how we send clear messages across time, for example nuclear waste sites and how we warn 50 generations down the road. This is a corrollary, what substances are the most dangerous over the long term? I assume it's some form of radioactive material , but which is the worst for the longest?
posted by Unioncat to Science & Nature (2 answers total) 2 users marked this as a favorite
Radioactive fuel waste-wise, Np-237 is probably it, with Pu-239 a distant runner up. They're both pretty bad.

High-level radioactive waste management
The most troublesome transuranic elements in spent fuel are neptunium-237 (half-life two million years) and plutonium-239 (half-life 24,000 years).
posted by zamboni at 7:23 AM on November 11, 2016 [1 favorite]

If you want to emphasize the "long term" over "most dangerous" the heavy metal lead is dangerous forever, as it is poisonous and never degrades. So, maybe a radioactive element which decays to an isotope of lead meets your criteria (i.e. dangerously radioactive for many years, decays to lead, which is poisonous forever). Examples include 238U (which decays to 206Pb) and 235U (which decays to 207Pb).
posted by RichardP at 7:44 AM on November 11, 2016 [4 favorites]

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