Polystyrene (Styrofoam)
PS / resin identification code 6
Instant noodle cups, trays, takeout containers. Released the most in a hot-water test.
Main uses
- Styrofoam trays and instant noodle cups
- Takeout containers
- Clear cups and lids
Found in food, water and the human body
- Hot water in takeout containers: release was polystyrene > polypropylene > PET > polylactic acid (Jin et al. 2024)
- Among takeout containers, rough-surfaced polystyrene containers released the most (Du et al. 2020)
- In one brand of bottled water, polystyrene was the most abundant by particle count (Qian et al. 2024)
- Blood: one of the 3 most common types, as “styrenics” (Leslie et al. 2022)
Detailed numbers by food: Microwave heating and takeout containers, Bottled water
Evaluations of raw materials and additives
- The raw material styrene is IARC Group 2A (evaluated in 2018)
- EFSA (2020): most migration into food was below 10 μg per kg (up to 230 μg). A genotoxicity concern when taken orally could not be ruled out, and further study is needed
IARC classifications rate the strength of evidence that something can cause cancer, not the size of the risk at everyday amounts.
Japan's standards (utensils, containers and packaging that touch food)
- MHLW Notification No. 370 (polystyrene): total styrenes in the material 5 mg/g or less. For expanded polystyrene used with hot water, total 2 mg/g or less, and styrene and ethylbenzene each 1 mg/g or less
General standards for all synthetic resins: cadmium and lead in the material 100 μg/g or less each, heavy metals migrating (as lead) 1 μg/mL or less, and others. Since June 2020, synthetic resins that touch food have been under a “positive list system” that sets which substances may be used (the transition period ended May 31, 2025). → Rules and regulation
Production in Japan
| Item | 2023 | 2024 | 2025 |
|---|---|---|---|
| Polystyrene, total | 921,318 t | 901,672 t | 897,314 t |
Compiled by the Japan Plastics Industry Federation (based on METI's production statistics). This is the amount made in Japan, not the amount used in Japan.
Sources
- Jin T, et al. J Hazard Mater 2024;475:134866 (PMID 38870856)
- Du F, et al. J Hazard Mater 2020;399:122969 (PMID 32526446)
- EFSA CEP Panel. EFSA J 2020;18(10):e06247 (styrene) (PMID 33133270)
- Consumer Affairs Agency, standards for utensils, containers and packaging (Notification No. 370, Part 3) (Japanese)
- IARC List of Classifications
- Japan Plastics Industry Federation, statistics (Japanese)
Last checked 2026-10-01. This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.