Microplastic Pollution in Table Salts from China.
Level 5 - mechanism / opinion, no new human data
Bench and product laboratory analysis with no human subjects (graded by design analogy)
PubMed 26486565 · doi:10.1021/acs.est.5b03163
What was done
Researchers purchased 15 brands of sea salts, lake salts, and rock/well salts from supermarkets across China. They measured the concentration, morphology, size distribution, and polymer composition of microplastics contained in each salt type.
What was found
Microplastic content was 550 to 681 particles/kg in sea salts, 43 to 364 particles/kg in lake salts, and 7 to 204 particles/kg in rock/well salts. The abundance of microplastics in sea salts was significantly higher than in lake or rock/well salts. In sea salts, fragments and fibers were the prevalent types, particles measuring less than 200 micrometers accounted for 55% of total microplastics, and the most common polymers were polyethylene terephthalate, polyethylene, and cellophane.
Why it matters
This study provides evidence of microplastic pollution in commercial sea salts, identifying an abiotic marine pathway for microplastic entry into the human food supply.
Limits
The study tested only 15 brands purchased in China. It does not measure human exposure levels, toxicological impact, bioavailability, or differentiate whether contamination originated in source waters versus industrial packaging and processing.
Cited by
- supports Consuming salt adds an estimated 7,000 microplastic particles to human diet annually, with sea salts containing between 550 and 681 microplastic particles per kilogram.