Plastic Bottle Safety A Consumer Guide to Recycling Symbols

Most plastic bottles carry a number from 1 to 7 stamped on the base. The figure identifies the resin family used in manufacturing, which in turn determines the container's physical properties and the conditions under which it can safely be used.

The codes are standardized, but they are not a ranking of safety or quality. Each material was developed for a particular purpose, and a resin suited to detergent packaging may be poorly suited to drinking water.

Understanding what a material cannot do is the starting point for protecting health. PET bottles, for instance, may generate carcinogenic compounds after repeated use or prolonged storage, which makes "drink and discard" the safest approach for that resin.

HDPE (code 02) and PP (code 05) are in theory reusable. In practice, however, the complex geometry of bottle bodies makes thorough cleaning difficult, and residual moisture encourages bacterial growth. Long-term reuse therefore carries a hygiene risk even when the plastic itself is stable.

Heat remains the most common source of trouble. Most plastic bottles, and PET in particular, deform physically at high temperatures, a process that can allow chemical components from the material to leach into the contents.

Plastic recovery is governed by strict criteria, and collection systems vary by jurisdiction. In Hong Kong, the official recycling network principally accepts PET (code 01) and HDPE (code 02) bottles, the two streams for which local processing capacity exists.

Items bearing codes 03 through 07 generally fall outside standard collection because their processing is more complex. These are typically channeled through specialist environmental organizations or designated drop-off points, where they can be sorted and handled in a way that limits environmental contamination.