https://en.wikipedia.org/wiki/Kosmos_954#Aftermath

When you talk of radiatoxicity what is usually meant is the hot particle theory which says that a bit of radioactive material lodged in one place is more likely to cause cancer, because the radiation given off repeatedly hits the same tissue. It turns out that in cohort studies done this is not true. Specifically people who have inhaled plutonium, an inadvisable thing to do, actually have lower rates of lung cancer.

Pu-238 has some radioactivity, although not as much as many fission products. Radioactivity is bad. But the fear over plutonium toxicity is actually overblown beyond the baseline radioactive dose it provides.