The Pipeline and Hazardous Materials Safety Administration (PHMSA) makes sure that things like pipelines (like straws) that carry things from one place to another, and hazardous materials (like dangerous potions) are transported safely and don’t hurt anyone.
PHMSA checks to make sure that the pipelines are strong and don’t have any cracks or leaks (like holes in your straw), so that they don’t let what’s inside escape and go where it shouldn’t go.
They also make sure that the things being transported, like dangerous chemicals or gases, are stored safely and aren’t likely to catch fire or hurt people if they accidentally get out. Just like you don't want to drink something that could make you sick, PHMSA wants to make sure people and the environment aren't hurt by anything carried in the pipelines or during transportation.
So, they make up rules to keep everyone safe and people with special jobs, like truck drivers or pipeline repairmen, have to follow the rules to make sure that everyone stays safe.