PET is used for refillable bottles; is it hygienically acceptable?

Yes, it is. Detailed studies have been completed that investigated the health, safety, and environmental aspects of using PET in refillable bottle systems.  Some of the countries who have approved the use of PET for refillable applications are Argentina, Austria, Brazil, Belgium, Chile, Columbia, Costa Rica, Denmark, Finland, Germany, Guatemala, Mexico, Namibia, Netherlands, Norway, Peru, Philippines, South Africa, Sweden, Switzerland, Thailand, and Uruguay.

Cleansing processes must be adequate to remove all bacteriological contaminants or render them inactive by sterilisation.  Procedures have been developed to clean and sterilise the containers to the same performance standards that are set for refillable glass containers.  Repeated cleaning tests with bottles of 'rough' interior wall surfaces (so that they will retain greater quantities of what has been stored into them) and contaminated with mixed spoilage yeasts compared favourably with glass packages.

A Code of Practice applies to refillable bottles that ensures maximum product safety and complete acceptance by the consumer.

The rumours circulating on the Internet that PET bottles are safe for one time only are groundless.  PET bottles do not release harmful chemicals when they are used repeatedly.