METAL STRAWS: Are created from plumbing, air conditioning, industrial and automotive tubing.
Copper: Look under your bathroom sink, water line to hot water heater or icemaker, you will see COPPER Tubing. Never meant for humans to drink from. Extruded (formed by melting copper and forcing through a round molded form covered in greases and release toxins which never stop emitting corrosive toxins.
THIS IS WHY A BRUSH IS NEEDED.
Stainless: Look at your automotive brake lines, air conditioning lines. Same exact 1/4" tubing. Same method of manufacture - extrusion through toxic molding. Brushes needed due to constant corrosive toxin release blended with whatever you are drinking.
PAPER STRAWS! ABSOLUTELY THE MOST UNHEALTHY. Made from all sorts of trash paper, cardboards, cleaning supplies and even yes toilet paper. Made in China, into a liquid 'slurry mulch', then bleached, and reformed into thin paper cut into slices and after SENDING EACH STRIP OF THREE TO MAKE THE STRAWS - ARE RUN THROUGH AN OPEN VAT OF GLUE. AND METAL FORMED AROUND A ROD WITH SAME TOXIN GREASE RELEASE.
Highly toxic and down right nasty.