NaCl
Ordinary, everyday, salt. Adds flavour to many recipes, just don’t over do it. Also used to help stop roads from icing up in wintery climates. Not good for the environment.
Now that sprint is almost here in the northern hemisphere, all that salt we used during the winter is going to end up in places it should not be. Run offs to our creeks and rivers. Into soils, making them less hospitable to plant life.
Unfortunately, the alternatives are more expensive, so we are back to the usual question. Continue the status quo, or spend more money in order to protect the environment.