[Wavery]

When pipe threaded items are screwed together there gaps between a lot of the threads as the male and female threads make contact and tighten in some areas. A small amount of water and air will fill the gaps in areas where no thread-to-thread contact is made. This starts corrosion and mineral deposits to fill those gaps. As steel corrodes, it expands causing the threads to tighten against themselves.

Teflon tape, anti-seize, and blue Loctite all achieve the same goal of filling those gaps with non-corrosive material that stays soft and aids in releasing the threads. This leaves no place for water and mineral intrusion, thereby, eliminating corrosion.

As for chemical intrusion from these preventative measures, I think it is a minimal issue with Teflon tape and properly cured Loctite. Anti-seize may or may not be a different issue. Personally, I never drink from the hot water faucet and our water filter is on the cold water side of the kitchen sink.