Microplastics in Salt: Is Sea Salt Making You Eat More Plastic?

The global study: 39 brands, 21 countries

Kim et al. (2018) in Environmental Science & Technology conducted the most comprehensive analysis of microplastics in commercial salt to date. The team sampled 39 salt brands purchased from 21 countries across Europe, North America, and Asia. The findings were unambiguous: 90% of salt brands contained microplastic particles.

The contamination varied significantly by salt type. Sea salt showed the highest concentrations — ranging from 0 to 1,674 microplastic particles per kilogram, with a mean substantially higher than other salt types. Lake salt showed moderate contamination (28–462 particles/kg), while rock salt had the lowest (0–148 particles/kg). Refined table salt, which undergoes additional processing, tended to have lower particle counts than unrefined sea salt.

The contamination level in sea salt correlated directly with the volume of plastic waste entering rivers and oceans in nearby regions — making sea salt effectively a microplastic index of local ocean pollution. Brands sourced from more polluted coastlines showed higher particle counts than those from less affected waters.

Why sea salt is more contaminated than other types

Sea salt is produced by evaporating seawater — either in open-air salt pans or through industrial evaporation. Because it is derived directly from ocean water, any microplastics suspended in the water are concentrated into the final product alongside the sodium chloride.

Rock salt and mined salt, by contrast, come from ancient underground deposits formed millions of years before plastic existed. They contain no synthetic polymers by origin. Any contamination in rock salt comes from the mining or packaging process, not the source material — which is why these types consistently show lower particle counts.

How much do you ingest from salt?

Using the Kim et al. data and standard dietary sodium intake figures, an adult consuming the WHO-recommended maximum of 5g of salt per day would ingest approximately 2,000 microplastic particles per year from salt alone if using a mid-range sea salt. At higher consumption levels — more typical of average Western diets — this figure rises proportionally.

This makes dietary salt a moderate but consistent exposure source. It is not in the same category as microwaving food in plastic or using plastic tea bags, but it contributes meaningfully to cumulative annual intake — and unlike some exposure sources, it is present at every meal.

Does the type of salt matter for health reasons beyond microplastics?

The health literature on sea salt versus table salt has focused primarily on mineral content and iodine supplementation — not microplastics. Sea salt does contain trace minerals absent in refined table salt, but these are present in quantities too small to be nutritionally significant for most people. The choice between salt types for mineral content is essentially a marketing argument.

When microplastic content is added to the comparison, the picture changes. Rock salt and refined table salt have meaningfully lower particle contamination than unrefined sea salt. For people who use significant quantities of salt in cooking and at the table, switching from sea salt to rock salt or refined iodised salt is a simple change that reduces one dietary exposure pathway.

What the research doesn't yet tell us

The 2018 Kim et al. study remains the most comprehensive global analysis. Since then, several regional studies have confirmed the pattern of sea salt contamination, and a 2025 critical review by Chell et al. in the Journal of Chromatography Open (DOI: 10.1016/j.jcoa.2025.100276) confirmed that sea salt consistently shows the highest contamination across salt types globally, with fragments and fibres under 200 μm being the most prevalent particle type. However, the health effects specifically from salt-derived microplastic ingestion have not been studied in isolation — the data on dose, accumulation, and long-term effects comes from the broader microplastics literature, not salt-specific research.

Practical guidance

If reducing microplastic exposure from salt is a priority, rock salt or refined iodised table salt has a lower particle burden than unrefined sea salt. This is not a dramatic intervention — salt contributes a relatively small fraction of total microplastic intake compared to sources like plastic cookware and containers — but it is an easy swap with no downside. The minerals marketed in sea salt are nutritionally negligible, and rock salt used in cooking performs identically.