Sterilization
If necessary, bottles can be sterilized by boiling in hot water, in a specialized bottle sterilization appliance (which typically uses steam) or in a specialized sterilization container that is microwaved. Modern bottles are difficult to sterilize in boiling water because they tend to float. Bottles were originally composed of glass which was dangerous when babies learned to feed themselves and held the bottle. Mainly for cost reasons, modern bottles are unbreakable plastic. Since bottles have to be made to withstand the heat of sterilization, the bottle can also withstand the heat of dishwashers.
There is some concern about Bisphenol A (BPA) leakage on polycarbonate bottles due to extended dishwasher or boiling. While bottles were traditionally sterilized in the past, unless there are infant health concerns, or concerns about water contamination, the current recommendation is that baby bottle sterilization can be replaced by cleaning with hot soapy water.
Read more about this topic: Baby Bottle