If you fill a tea cup or glass with cold water there will invariably be a few bubbles floating on the surface. It’s due to detergent residue, even if the cup is from a dishwasher.
There are some real nasty immune supresents in those bubbles, like polychlorinated biphenyls for example, that builds up over time and are extremely differcult to detoxify.
Next time you have the opportunity check how many suds are left on the crockery after an old lady washes up.
No tea for me thanks Mrs Smith.