There is a system of classification of plastics called identification code of resin, which is the number placed at the bottom of the bottles and food containers that identifies the type of the plastic resin with which they were made. The most toxic plastic for health are 7, 3 and 6 (in that order), while the safest are 1, 2, 4 and 5 (in that order). Plastic 1: PET (polyethylene terephthalate) plastic 2: HDPE (high density polyethylene) plastic 3: PVC (polyvinyl chloride) plastic 4: LDPE (low density polyethylene) plastic 5: PP (polypropylene) plastic 6: plastic (polystyrene) PS 7: others not listed
