The waste-management giant revealed that a homeless man in Bristol recently broke limbs after the trade refuse bin he was in was tipped into the back of a lorry.
A west Midlands man lost his life in a similar accident and Biffa recorded 47 near misses between April and December 2003.
But winter is the worst time as drunk and homeless people are tempted to shelter from the cold in large bins behind pubs and shops. Children also climb into bins when they are playing.
Biffa is asking for firms who know their bins are being used in this way to ensure they lock them whenever possible.
Health and safety support manager Ray Hipkin said: "Containers may seem like fun places to play for children or warm places to sleep for the homeless, but these people are risking their lives.
"There is a clear checking procedure for our operatives and this is laid down in the driver's handbook. Many bins also carry warnings, but anyone who is asleep, drunk or determined to remain hidden can often remain undiscovered despite a driver's best efforts."