The initial production of glass is worse for the environment than the production of plastic. But when we take into account what becomes of the packaging after disposal, glass has less of an impact if it ends up in the environment since glass degrades into mineral. It is not possible, however, to create new glass packaging from used glass packaging. Plastic can be recycled and used in new applications, like the creation of synthetic fleece. But synthetic fleece and other plastic-based textiles shed microplastics when laundered, which often are washed out to sea. Microplastics generated in washing machines have a direct path to our oceans. Another consideration is that because glass is a relatively heavy packaging, it often incurs a much larger carbon footprint to transport compared to lighter packaging options like plastic.
Glass is not recycled in Iceland, but rather crushed and used as construction aggregate. As such, glass does not make for a good disposable material; it is much better suited to reusable applications. Recycling plastic packaging can be better than disposable glass packaging. But how we dispose of the packaging makes all the difference, i.e., if we make sure the material ends up in a recycling channel.