Microplastics in table salt (sea salt, rock salt, lake salt)
Higher microplastic levels have been reported in sea salt, which is made from seawater. However, the ranking can flip depending on the lower size limit of the particles counted and on whether they are counted by “number” or measured by “weight,” and studies differ from one another by about 100 times.
Amounts found in studies
| Study | What was tested | Size range and method | Results |
|---|---|---|---|
| Kim et al. (2018) | 39 brands from 21 countries | — | None found in 3 brands. Tended to be higher in sea salt and lower in rock salt. Japanese salt was among those with detections |
| Kwon et al. (2025) | Sea salt, rock salt, lake salt | Py-GC/MS (weight) | Per kg: sea salt 584.5 μg, rock salt 34.2 μg, lake salt 6.2 μg. Polystyrene thought to come from packaging was found in rock salt |
| Özçifçi et al. (2023) | 36 samples from Türkiye | FTIR (number) | Per kg: rock salt 44 particles, lake salt 38, sea salt 28 (by number, rock salt was higher) |
| Thiele et al. (2023) | 13 brands from Europe | Down to 0.005 mm | 74–1155 particles per kg in every brand |
| Ruan et al. (2024) | Sea salt from 6 production areas (including the Seto Inland Sea) | SERS and SRS (nanoplastics) | Nanoplastics of 0.2–1 μm detected. Mostly polyethylene and polypropylene |
Results can differ by orders of magnitude depending on the smallest particle size counted and whether particles are counted or weighed. Numbers from different studies cannot be compared directly (→ Why numbers differ).
Good to know
- A Korean study that pooled 150 reported values for table salt (Lee et al. 2021) found wide scatter, from 0 to 39,800 particles per kg, with 10–600 times differences depending on the identification method (counts were highest by visual inspection, then FTIR, then Raman). The lower size limit of the particles counted correlated with how high the results were.
- Among the co-authors of Kwon 2025 are researchers from the manufacturer of the measuring instrument (Py-GC/MS) (they declared “none” for conflicts of interest).
- How to choose salt, Guérande salt, fleur de sel, and the test results that manufacturers have published are covered in the explainer “How to choose salt.”
Data from Japan
Japanese salt is included in the international surveys of Kim 2018 and Karami 2017, and sea salt from the Seto Inland Sea is included in Ruan 2024 (the individual Japanese values are unconfirmed in the supplementary material). We found no study that targeted Japanese salt only.
Types of plastic found
Related explainers
Sources
- Kim JS, et al. Environ Sci Technol 2018;52(21):12819-12828 (PMID 30285421)
- Kwon, et al. Food Chem 2025;467:142193 (PMID 39626558)
- Özçifçi, et al. Food Chem Toxicol 2023;175:113698 (PMID 36889431)
- Thiele CJ, et al. Ecotoxicol Environ Saf 2023 (PMID 36934543)
- Lee HJ, et al. J Hazard Mater 2021;402:123743 (review of salt studies) (PMID 33254769)
- Ruan X, et al. Environ Sci Technol 2024;58:9091 (PMID 38709279)
Last checked 2026-10-01. “Confirmed in the abstract” means we report only what the paper's abstract says. This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.