In the 50's, 60's and 70's, as the number of visitors to the Smokies was increasing significantly, the peril to the black bear was increasing in direct proportion. And in masses they came to see a bear.
Black bears have a natural fear of humans.
In their first year and a half, the cubs are constantly with their mommas, and the fear of humans is one of the primary lessons of survival that she teaches. Put those characteristics together with tens of thousands of opportunistic human visitors with food as well as the desire to see a bear, and you can predict the outcome. That's when the trouble starts. Frequently not only do bears eat food that is intentionally or unintentionally provided for them, but they ingest the items the food came in contact with too. Frequently it never comes back up, or out, and the bear dies a slow and very painful death.