The mark is / should be at the bottom of any food container (for example the bottles for mineral water).
1. PET (polyethylene terephthalate) - acceptable poison
2. PP (polypropylene) - acceptable poison
3. HDPE (high-density polyethylene) - acceptable poison
4. PELD / LDPE (low-density polyethylene) - highly poison
5. PVC / V (polyvinyl chloride) - deadly (irreversible damages)
6. PS / PS-E (polystyrene) - deadly (irreversible damages)
7. OTHER / О (others, mostly polycarbonate & polylactide) - deadly (irreversible damages)