The 1986 Chernobyl nuclear plant explosion may seem far away in time and place to Montanans, but radioactivity from that disaster and from decades of nuclear bomb tests can be traced to every American and we still don’t really know the health consequences.

That was one of the messages from Kate Brown, a science historian from MIT, who spoke to a packed crowd Thursday at the Museum of the Rockies as part of Montana State University’s Science Matters lecture series.

“All humans have radioactivity in their bodies,” Brown said. She is the author of “Manual for Survival” on Chernobyl and “Plutopia,” on disasters and cover-ups at plutonium plants from Russia to Hanford, Washington.

Chernobyl should be seen, not as a one-time accident, Brown argued, but as part of a larger, still ongoing story of global nuclear contamination and Russian, American and the international officials hiding the truth.