Earlier quoted context omitted.
Many generations beyond ours. Someone else posted this article which has more information: https://www.abc.net.au/news/2017-11-27/the-dome-runit-island... "Some of the debris buried beneath the dome includes plutonium-239, a fissile isotope used in nuclear warheads which is one of the most toxic substances on earth. It has a radioactive half-life of 24,100 years."
Generally speaking, the longer the half-life, the less dangerous (in terms of radioactivity) something is. Also, pl239 primarily emits alpha particles, which are stopped by clothing and don't penetrate skin. Maybe a real physicist can chime in, but I don't think there's much risk of standing around subcritical quantities of the stuff. The chemical toxicity is a different matter though.
As an alpha emitter, plutonium-239 is not particularly dangerous as an external radiation source, but if it is ingested or breathed in as dust it is very dangerous and carcinogenic. It has been estimated that a pound (454 grams) of plutonium inhaled as plutonium oxide dust could give cancer to two million people. However, ingested plutonium is by far less dangerous as only a tiny fraction is absorbed in gastrointestinal tract. 800 mg would be unlikely to cause a major health risk as far as radiation is concerned. As a heavy metal, plutonium is also toxic.