That's a great question and something many people don't consider when buying a new bin. Generally, most modern outdoor trash cans are designed with safety in mind. Manufacturers understand they are used around homes, gardens, and often by children or pets.
You'll typically find that high-quality plastic and metal trash cans have rolled or rounded edges, especially around the lid and the opening. This design isn't just for safety; it also adds structural strength and prevents the plastic from cracking. The seams are often welded or smoothed over to eliminate any burrs or sharp protrusions.
However, it's always a good idea to do a quick safety check yourself. When you get a new can, run your hand along the inner and outer rims and the lid's edge. Be mindful of cheaper, thin-metal cans, as these can sometimes develop sharp edges if they get dented or rust over time. If you are particularly concerned, look for models specifically advertised as having "child-safe" or "rounded" designs. Ultimately, while the risk is low with a well-made product, your vigilance is the best guarantee for a safe outdoor space.